Guard For Firearm Muzzle Attachments

Abstract

A muzzle attachment guard for a firearm includes a base and a guard. The base defines a receiver configured to receive an engagement mechanism of a muzzle end of a firearm barrel. The engagement mechanism remains accessible from within the cage when the guard is attached to the firearm barrel. The cage defines at least one opening large enough to allow the passage of a user's fingers and/or tools to access a muzzle attachment disposed inside of the cage.

Description

RELATED APPLICATIONS

This application claims the benefit of co-pending U.S. Provisional Patent Application No. 63/452,288, filed on Mar. 15, 2023, by the same inventor, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to firearm accessories, and more particularly to firearm muzzle attachments.

Description of the Background Art

Many firearm barrels are equipped with muzzle attachments such as, for example, suppressors, muzzle brakes, flash hiders, etc. When a firearm equipped with a muzzle attachment is discharged, the muzzle attachments heats up. If the firearm is discharged at a high enough shot frequency, the muzzle attachment can reach temperatures that are hot enough to burn an individual if touched. This is particularly problematic in firearms intended for high shot frequencies such as, for example, semi-automatic and automatic weapons. Another problem with muzzle attachments is that when they heat up, the heat rising therefrom causes a mirage effect that distorts the shooter's line of sight.

In many regions, laws require the length of a barrel to meet certain specifications. Depending on the region, a muzzle attachment may be considered part of the barrel and must be included in determining the overall barrel length. In some cases, the addition of a muzzle attachment may render an otherwise illegal barrel length legal.

SUMMARY

The present invention overcomes the problems associated with the prior art by providing a guard assembly for a firearm muzzle attachment. The invention facilitates attachment and detachment of various muzzle attachments, without removing the guard assembly.

Example guard assemblies for guarding muzzle attachments fixed to muzzles of firearms by engagement mechanisms of the muzzles of the firearm are disclosed. An example guard assembly includes a base and a guard. The base defines a receiver configured to receive the muzzle of the firearm. The guard extends from the base in a forward direction and at least partially surrounds a bore axis of the firearm. The guard defines an interior space, wherein the muzzle attachment can be disposed. The guard can define a first passage extending from outside of the guard to the interior space of the guard. The first passage has a first dimension measured along a direction parallel to the bore axis and a second dimension measured in a plane perpendicular to the bore axis. The first dimension is sufficient to permit a tool to pass through the first passage and engage the muzzle attachment. The second dimension is sufficient to facilitate rotation of the tool in the plane and about the bore axis.

In an example guard assembly, the base can further define a bore extending in a direction perpendicular to the bore axis of the firearm from an outer edge of the base into the receiver. The guard can define an aperture aligned with the bore, and the guard assembly can further include a pin. The pin can be configured to be permanently fixed in the bore in engagement with the muzzle of the firearm, to permanently fix the guard assembly to the muzzle of the firearm.

In an example guard assembly, the receiver can define a cylindrical opening that is configured to engage a complementary cylindrical surface of the muzzle of the firearm. The cylindrical opening can include a first thread set configured to engage a complementary second thread set on the cylindrical surface of the muzzle of the firearm. The engagement mechanism of the muzzle, or at least a portion thereof, can remain accessible when the muzzle is received by the receiver. The guard can be rigidly fixed to the base.

In an example guard assembly, the base is disposed within an inch of a second plane that is perpendicular to the bore axis and passes through the first opening. The second dimension of the first passage subtends an angle of at least 60 degrees at the bore axis. That is, a line passing from the bore axis to a first edge of the first opening makes an angle of at least 60 degrees with a second line passing from said bore axis to a second edge of said first opening. Optionally, the second dimension of the first passage can subtend an angle of at least 90 degrees at the bore axis. Furthermore, the second dimension of the first passage can subtend an angle greater than 180 degrees at the bore axis.

In particular examples, the first opening can be large enough to facilitate the passage of the muzzle attachment.

In other example guard assemblies, the guard can additionally define a second passage extending from outside of the cage to the interior space of the cage. The second passage includes a third dimension measured along a direction parallel to the bore axis, and a fourth dimension measured in a plane perpendicular to the bore axis. The second passage can be disposed on an opposite side of the guard from the first passage. The second dimension of the first passage can subtend an angle of at least 60 degrees at the bore axis, and the fourth dimension of the second passage can also subtend an angle of at least 60 degrees at the bore axis. Optionally, the second dimension of the first opening can subtend an angle of at least 90 degrees at the bore axis, and the fourth dimension of the second opening can also subtend an angle of at least 90 degrees at the bore axis. Additionally, the first passage and the second passage can be symmetrical about the bore axis.

In example guard assemblies, the base can include a plate having a cylindrical outer surface, and the guard can include a shell having cylindrical inner surface that mates with the cylindrical outer surface of the base plate. The guard can include a cylindrical shell having a wall that defines the first passage. The cylindrical shell can have a first end fixed to the base, and the cylindrical shell can include a second end opposite the first end. The second end can include an opening with a peripheral edge. The peripheral edge can include a first segment, a second segment, a third segment, and a fourth segment. The second segment can be disposed between the first segment and the third segment, and the first segment can be disposed between the second segment and the fourth segment. The first segment and the third segment can be disposed on a first side of a second plane perpendicular to the bore axis, and the second segment and the fourth segment can be disposed on an opposite side of the second plane.

Example guard assemblies can also include a heat shield disposed at least partially around the guard. Optionally, the heat shield can define at least one opening through the heat shield. As another option, the heat shield can be made of spring steel. The heat shield can also be selectively removable from the guard. As yet another option, the heat shield can include at least one tab configured to engage at least one opening of the guard.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements:

FIG. 1 is a front perspective view of an example muzzle attachment and an example muzzle attachment guard assembly mounted on a firearm barrel;

FIG. 2 is a rear perspective view of the muzzle attachment and the muzzle attachment guard assembly of FIG. 1 mounted on the firearm barrel;

FIG. 3 is a front perspective view of the muzzle attachment and the muzzle attachment guard assembly of FIG. 1 exploded from the firearm barrel;

FIG. 4 is a front perspective exploded view of the guard of the muzzle attachment guard assembly of FIG. 1;

FIG. 5 is a cross sectional perspective view of the base of the guard of FIG. 4;

FIG. 6A is a cross sectional side view taken along line A-A of FIG. 4, illustrating a first step of permanently fixing the guard of FIG. 1 to the barrel;

FIG. 6B is a cross sectional side view taken along line A-A of FIG. 4, illustrating a second step of permanently fixing the guard of FIG. 1 to the barrel;

FIG. 6C is a cross sectional side view taken along line A-A of FIG. 4, illustrating a third step of permanently fixing the guard of FIG. 1 to the barrel;

FIG. 6D is a cross sectional side view taken along line A-A of FIG. 4, illustrating a fourth step of permanently fixing the guard of FIG. 1 to the barrel;

FIG. 7A is a top plan view of the guard of FIG. 1 mounted to the barrel of FIG. 1;

FIG. 7B is a top plan view of the guard and suppressor of FIG. 1 mounted to the barrel of FIG. 1;

FIG. 8 is front perspective view of the guard of FIG. 1 and a muzzle brake mounted on the barrel of FIG. 1;

FIG. 9 is a cross-sectional side view of the guard and muzzle brake of FIG. 8 mounted on the barrel of FIG. 8;

FIG. 10 is another cross-sectional side view of the guard and muzzle brake of FIG. 8 mounted on the barrel of FIG. 8;

FIG. 11 is a rear perspective, exploded view of another example muzzle attachment guard assembly of the present invention;

FIG. 12 is a rear perspective, exploded view of the muzzle attachment guard assembly of FIG. 11;

FIG. 13 is a side plan view of the muzzle attachment guard assembly of FIG. 11;

FIG. 14 is a cross-sectional side view of the muzzle attachment guard assembly of FIG. 11 and muzzle brake of FIG. 8 mounted on the barrel of FIG. 8;

FIG. 15 is rear perspective view of an alternate base;

FIG. 16 is a front perspective view of the base of FIG. 15;

FIG. 17 is a cross-sectional side view of the base of FIG. 15, taken along line F-F;

FIG. 18 is rear perspective view of another alternate base;

FIG. 19 is a front perspective view of the base of FIG. 18;

FIG. 20 is a cross-sectional side view of the base of FIG. 18, taken along line G-G;

FIG. 21 is rear perspective view of another alternate base;

FIG. 22 is a front perspective view of the base of FIG. 21;

FIG. 23 is a cross-sectional side view of the base of FIG. 21, taken along line H-H;

FIG. 24 is rear perspective view of another alternate base;

FIG. 25 is a front perspective view of the base of FIG. 24;

FIG. 26 is a cross-sectional side view of the base of FIG. 24, taken along line I-I;

FIG. 27 is a rear, bottom perspective view of an example alternate heat shield;

FIG. 28 is a rear, bottom perspective view of another example alternate heat shield;

FIG. 29 is a rear perspective view of an example alternate cage;

FIG. 30 is a side plan view of the cage of FIG. 29;

FIG. 31 is cross-sectional view of the cage of FIG. 29, taken along line J-J of FIG. 29;

FIG. 32 is a top plan view of the cage of FIG. 29, with a suppressor disposed therein;

FIG. 33 is a rear perspective view of another example alternate cage;

FIG. 34 is a side plan view of the cage of FIG. 33;

FIG. 35 is cross-sectional view of the cage of FIG. 33, taken along line K-K of FIG. 33;

FIG. 36 is a top plan view of the cage of FIG. 33, with a suppressor disposed therein; and

FIG. 37 is a flowchart summarizing a method of attaching a muzzle attachment guard to a barrel.

DETAILED DESCRIPTION

The present invention overcomes problems associated with the prior art, by providing a device that guards muzzle attachments from being inadvertently touched or damaged, provides a heat shield that eliminates mirage effect, and provides an option to make the device a permanent part of the overall barrel length. In the following description, numerous specific details are set forth (e.g., materials, muzzle attachment types, and so on) in order to provide a thorough understanding of the invention. Those skilled in the art will recognize, however, that the invention may be practiced apart from these specific details. In other instances, details of well-known manufacturing practices (e.g., machining, welding, tempering, and so on) and components have been omitted, so as not to unnecessarily obscure the present invention.

FIGS. 1 and 2 show a front perspective view and a rear perspective view, respectively, of a muzzle attachment and a muzzle attachment guard assembly 100 mounted on a firearm barrel 102. The muzzle attachment is, for example, a suppressor 104, but can be any type of muzzle attachment (e.g., a silencer, a flash suppressor, flash hider/compensator, etc.).

When firearm barrel 102 is discharged at a high shot frequency, suppressor 104 heats up and becomes dangerous to the touch. To prevent individuals from inadvertently touching suppressor 104 and getting burned, assembly 100 substantially surrounds suppressor 104. Assembly 100 also eliminates the “mirage effect” that could otherwise obstruct the shooter's line of sight. In other words, assembly 100 functions as a heat shield to prevent the hot air around suppressor 104 from rising up into the shooter's line of sight and causing refractory problems that adversely affect targeting. As will be discussed in further detail with reference to upcoming figures, assembly 100 also provides various passageways, through which tools (e.g., wrenches, screwdrivers, user's hands/fingers, and so on) can access the side and rear (not visible) of suppressor 104 through the side or top of assembly 100, rather than just the front.

FIG. 3 is a front perspective view of assembly 100 and suppressor 104, exploded from barrel 102 along a bore axis 300 of barrel 102. Bore axis 300 is shown staggered so that the barrel 102, assembly 100, and suppressor 104 fit within the boundaries of the page. However, those skilled in the art will recognize that bore axis 300 is a straight axis with no staggering.

Example embodiments are described herein with nomenclature that is well-known in the firearm field. For example, barrel 102 includes bore axis 300, which is the axis that a bullet travels along through barrel 102. As another example, barrel 102 includes a throat end 302 through which a bullet enters barrel 102 upon being discharged. Typically, the throat end 302 is coupled to a receiver of the firearm. As yet another example, barrel 102 includes a muzzle end 304, opposite throat end 302, through which the bullet exits barrel 102.

Muzzle end 304 includes an engagement mechanism which, in this example, includes a thread set 306 formed on the outer surface of muzzle end 304 to facilitate the mounting of muzzle attachments to barrel 102. The thread specifications of thread set 306 can be, by way of non-limiting example, ½-28RH male, and thread set 306 extends approximately 0.625 in along axis 300. Of course, the thread specifications can vary based on the type and caliber of the firearm. In this example, barrel 102 is part of a high shot frequency (e.g., rapid fire) firearm, such as an automatic firearm or a semi-automatic firearm.

Muzzle attachments also include an entrance end through which bullets enter and an opposite exit end through which bullets exit. Accordingly, suppressor 104 includes an entrance end 308, through which bullets enter suppressor 104, and an exit end 310, through which bullets exit suppressor 104. Entrance end 308 includes a female thread set (not visible) that is complementary to male thread set 306 of barrel 102, which facilitates the attachment of suppressor 104 to barrel 102. That is, the female thread set of suppressor 104 is also ½-28RH.

Muzzle attachment guard assembly 100 includes a guard 312 and an optional heat shield 314. During assembly, guard 312 is first connected directly to muzzle end 304 of barrel 102, with at least a portion of muzzle end 304 of barrel 102 being accessible from an interior space 316 of guard 312. With guard 312 connected to barrel 102, suppressor 104 is then positioned in interior space 316, either through an open front end 318 of guard 312 or through one of two side passages 320 of guard 312. With suppressor 104 disposed in interior space 316 of guard 312, entrance end 308 of suppressor 104 is then connected to (e.g., screwed onto) the portion of muzzle end 304 that is accessible from interior space 316. In this case, the female thread set (not shown) of entrance end 308 of suppressor 104 is threaded onto the end portion of complementary male thread set 306 of barrel 102, which extends into interior space 316. With guard 312 and suppressor 104 connected to barrel 102, heat shield 314 can, optionally, be positioned around guard 312. Heat shield 314 is a tubular section of insulating and heat resistant material such as, for example, heat resistant fabric, fiberglass, silicone, etc. The insulating properties of heat shield 314 make it safe to touch when suppressor 104 is hot and also prevents the hot air surrounding suppressor 104 from rising up into the shooter's line of sight and causing what is known as the “mirage effect”. The inner diameter of heat shield 314 may be slightly larger than the outer diameter of guard 312, so that heat shield can easily slide on and off guard 312. If heat shield 314 is made from an elastic material (e.g. silicone, coated spring-steel, or the like), the inner diameter of heat shield 314 may be the same or slightly less than the outer diameter of guard 312, so that heat shield 314 compresses around the outer surface of guard 312 and is held in place by frictional forces between guard 312 and heat shield 314.

FIG. 4 shows a front perspective view of guard 312 exploded along bore axis 300. Guard 312 includes a base 400 and a cage 402. In the example embodiment, base 400 and cage 402 are two discrete structures that are formed separately and then fixed together (e.g., welded, compression fit, screwed, or otherwise mechanically engaged). However, guard 312 may also be formed as a single monolithic structure. For example, guard 312 may be machined from a single billet of material, cast from metal, stamped/bent from a sheet metal blank, or molded from heat resistant polymer.

Base 400 is a metal plate that defines a receiver 404, a plurality of apertures 406, a cylindrical outer surface 408, and a set of bores 410. Receiver 404 is configured to receive muzzle end 304 of barrel 102. That is, receiver 404 is an aperture that includes a female thread set 412 that is configured to thread onto and off of complementary thread set 306 of barrel 102. Apertures 406 pass completely through base 400 and provide several functions including, but not limited to, providing passageways through which tools can access muzzle attachments with the interior space 316 of guard 312, providing an engagement feature for tools (e.g., wrench) that can be used to tighten guard 312 onto barrel 102, and providing air vents through which hot air can exit the interior space 316 of guard 312.

Cylindrical outer surface 408 is configured to mate with a cylindrical inner surface 416 of cage 402. When outer surface 408 of base 400 is mated with inner surface 416 of cage 402, each of bores 410 is coaxially aligned with a respective aperture 418 of cage 402. When guard 312 is assembled, bores 410 and apertures 418 both extend along an axis 420 that perpendicularly intersects bore axis 300. As will be discussed in further detail with reference to FIGS. 6A-6D, bores 410 and apertures 418 are configured to receive pins for permanently mounting guard 312 to barrel 102.

Cage 402 is a metal tubular structure that extends forward from base 400 along axis 300. The sidewall of cage 402 defines various relatively large passages, through which interior space 316, and muzzle attachments disposed therein, can be accessed by tools and the user's hands. Side passage 320 is large enough to insert muzzle attachments through, so that they don't have to be dropped through open front end 318 of guard 312. Side passage 320 is also large enough in the vertical direction to allow a wrench to turn a muzzle attachment at least 60 degrees about axis 300, with the handle of the wrench extending through side passage 320 to the outside of cage 402. Each of side passages 320 are intentionally disposed on opposite sides of cage 402, 180 degrees apart, so that a user can grasp opposing sides of a muzzle attachment disposed in interior space 316 with their hand(s) and/or a tool capable of engaging both sides of a muzzle attachment.

Cage 402 additionally defines a plurality of upper and lower passages 422 that provide access to interior space 316. In addition to providing access to interior space 316 from outside of cage 402, passages 320 and 422 of cage 402 also function as air vents, through which hot air can escape cage 402. Passages 422 also advantageously reduce the overall weight of guard 312.

As shown, the top and bottom of front end 318 of cage 402 include relieved portions 424 and 426, respectively. Relieved portions 424 and 426 provide access to the front end of a muzzle attachment disposed in interior space 316, while the non-relieved sides of front end 318 extend at least as far forward as the muzzle attachment, thereby helping to prevent inadvertent impact to the front end of the muzzle attachment.

Cage 402 is formed by cutting passages through the sidewalls of a metal tube. However, cage 402 can be formed by other means. For example, cage 402 may be formed by cutting passages through a piece of sheet metal, bending the sheet metal into a tube shape, and then welding the opposing ends of the sheet metal together to hold the tubular form. Cage 402 may also be formed from multiple discrete elongated structures, such as rods or strips, that extend from base 400.

FIG. 5 is a rear perspective, cross-sectional view of base 400 taken along line A-A of FIG. 4. In addition to thread set 412, receiver 404 also defines a counterbore 500 that has a larger diameter than that of thread set 412. Counterbore 500 defines a smooth cylindrical bore that is configured to mate with a non-threaded portion 502 (shown in FIG. 6A-6D) muzzle end 304 of barrel 102 in a coaxial relationship. As an alternative, a smooth cylindrical surface can be substituted for thread set 412. In such a case, base 400 would be secured to muzzle end 304 by a muzzle attachment, such that base 400 would function similar to a washer. Bore 410 extends along axis 414, which perpendicularly intersects axis 300. The center of the six cylindrical apertures 406 are spaced 60 degrees about axis 300, which passes through the center of receiver 404.

FIGS. 6A-6D show cross-sectional side views of barrel 102 and guard 312 taken along line A-A of FIG. 4, during a process of converting guard 312 into a permanent extension of barrel 102. In a first step, illustrated in FIG. 6A, guard 312 is threaded onto barrel 102 such that thread set 412 of base 400 engages complementary thread set 306 of muzzle end 304, and counterbore 500 of base 400 engages non-threaded portion 502 of muzzle end 304. Next, as illustrated in FIG. 6B, a drill bit 600 is aligned with the first of two bores 410 and then advanced along axis 414 to drill partially into muzzle end 304, to form a first recess. Drill bit 600 is then aligned with the second of the two bores 410 and then advanced along axis 414, to drill partially into muzzle end 304, at a location 180 degrees From the first location, to form a second recess. Then, as illustrated in FIG. 6C, a cylindrical metal pin 602 is disposed in each bore 410, such that each of pins 602 is partially seated in a respective drilled portion (recess) of muzzle end 304. Finally, as illustrated in FIG. 6D, the outer ends of pins 602 are bonded to cage 402, via welds 604 or some other permanent means. Although the permanent attachment of guard 312 to barrel 102 is shown using two pins 602, the permanent attachment of guard 312 to barrel 102 may be achieved with as little as one pin 602 or more than two pins 602. For example, base 400 may include three bores 410 evenly spaced 120 degrees about axis 300.

With welds 604 in place, guard 312 may be considered a permanent part of barrel 102 according to the laws of some jurisdictions. That is, the overall legal length of barrel 102 may be measured from throat end 302 of barrel 102 to the front end of cage 402. With welds 604 in place, guard 312 may be removed from the rest of barrel 102 without damaging barrel 102 (other than the slightly drilled recesses) by cutting welds 604, removing pins 602, and unscrewing guard 312 from thread set 306 of muzzle end 304.

FIG. 7A shows a top plan view of guard 312 mounted to muzzle end 304 of barrel 102. The top view shows that the top and bottom edges 700 of side passages 320 are located much closer to a center plane B-B (perpendicular to the plane of the page) than inner surface 416 at the sides of cage 402. In particular, a first distance (d1) is the closest distance from plane B-B to an edge 700 of a side passage 320. A second distance (d2) is the longest distance from plane B-B to inner surface 416 (i.e., the inner radius of the circular cross-section of guard 312). First distance (d1) being substantially shorter than second distance (d2) allows a user to grasp a muzzle attachment disposed in interior space 316, to facilitate mounting/dismounting of the muzzle attachment.

FIG. 7B shows a top plan view of guard 312 mounted to muzzle end 304 of barrel 102 with suppressor 104 attached to muzzle end 304. A third distance (d3) is the longest distance from plane B-B to an outer surface of a suppressor 104 (i.e., the outer diameter of suppressor 104). Because third distance (d3) is greater than first distance (d1), a user can easily access and grasp opposing sides of suppressor 104 through side passages 320. Moreover, because third distance (d3) is greater than first distance (di) but less than second distance (d2), the outer surface of suppressor 104 is accessible through openings 320, but does not extend beyond the outer cylindrical boundary of guard 104. Similarly, relieved portions 424 and 426 also provide access for a user to grasp the front end of suppressor 104.

FIG. 8 is a front perspective view of guard 312 and a muzzle attachment mounted to muzzle end 304 (not visible) of barrel 102. In this example, the muzzle attachment is a muzzle brake 800 that is disposed in interior space 316 and threaded onto thread set 306. The dimensions of side passages 320 are sufficient to allow muzzle brake 800 to be moved into and out of interior space 316 through one of side passages 320, during the attachment of muzzle brake 800 to barrel 102. Once muzzle brake 800 is disposed in interior space 316, a user may pass their fingers into interior space 316 through side passages 320 to manipulate the position and/or orientation of muzzle brake 800 as needed to mount/dismount muzzle break 800 (e.g., screwing muzzle brake 800 onto thread set 306).

FIG. 9 is a cross-sectional side view of guard 312 and muzzle brake 800 mounted to muzzle end 304 of barrel 102, taken along line C-C of FIG. 8. As shown, the vertical height (H1) of passages 320 is greater than the vertical height (H2) of muzzle brake 800 and is multiple times greater than the vertical height (H3) of bore 900 of barrel 102. In this example, vertical height (H1) of passages 320 is approximately four times greater than the vertical height (H3) of bore 900.

FIG. 10 shows a cross-sectional side view of guard 312 and muzzle brake 800 mounted to muzzle end 304 of barrel 102, taken along line D-D of FIG. 8. Each of passages 320 extends at least 60 degrees about axis 300 within the YX plane of FIGS. 8-10, between edges 700. This allows a wrench extending through passage 320 to rotate a hexagonal base 1000 of muzzle brake 800 at least 60 degrees within YX plane. Because base 1000 is six-sided, the 60 degree rotation of the wrench allows muzzle brake 800 to be rotated 60 degrees so that the wrench can then access another two parallel sides of base 1000 and continue rotating brake 800 about axis 300. Alternatively, a single large passage may be substituted for the two side passages 320. For example, cage 402 may define one large passageway extending up to just less than 360 degrees about axis 300 and within YX plane. The upper angular limit on a single passage would depend on the material from which guard 312 is constructed and, therefore, the width of material that must remain to provide sufficiently rigid support for the remainder of guard 312 (i.e., the portion of guard 312 on the side of the opening opposite base 400).

FIG. 11 shows a rear perspective view of another example muzzle attachment guard assembly 1100, which includes a guard 1102 and an optional heat shield 1104 exploded therefrom along axis 300. Like assembly 100, assembly 1100 is configured to be mounted to the muzzle end of a firearm barrel that is hosting a muzzle attachment, to prevent individuals from getting burned when the muzzle attachment gets hot.

Guard 1102 is configured to mount to the muzzle end 304 of barrel 102 in the same fashion as previously described guard 100. Guard 1102 surrounds a muzzle attachment that is also mounted to the muzzle end of the barrel, to prevent individuals from inadvertently coming into contact with the muzzle attachment.

Heat shield 1104 can be mounted around guard 1102 to protect users from inadvertently touching guard 1102 when guard 1102 is heated by a muzzle attachment disposed therein. With guard 1102 mounted on the muzzle end of a barrel, heat shield 1104 can be selectively engaged or disengaged from guard 1102. For example, heat shield 1104 can be dimensioned to snugly fit around guard 1102, so that heat shield 1104 can be slid on and off of guard 1102, but held in place by frictional forces between guard 1102 and heat shield 1104 during use of the firearm.

Like assembly 100, assembly 1100 prevents individuals from inadvertently touching suppressor 104 and getting burned. Assembly 100 substantially surrounds suppressor 104. Assembly 1100 also eliminates the “mirage effect” that could otherwise distort the shooter's line of sight. In other words, assembly 1100 functions as a heat shield to prevent the hot air around suppressor 104 from rising up into the shooter's line of sight. As will be discussed in further detail with reference to upcoming figures, assembly 1100 provides various passageways through which tools (e.g., wrenches, screwdrivers, etc.) can access the side and rear (not visible) of suppressor 104 through the side of assembly 100 rather than just through the front.

FIG. 12 shows a rear perspective view of guard 1102 exploded along axis 300. Guard 1102 includes a base 1200 and a cage 1202. In the example embodiment, base 1200 and cage 1202 are two discrete structures that are formed separately and then fixed together (e.g., welded, compression fit, screwed, mechanically engaged, and so on). However, guard 1102 may also be formed as a single, monolithic structure. For example, guard 1102 may be machined from a single billet of material, cast from metal, stamped/bent from a sheet metal blank, or molded from heat resistant polymer.

Base 1200 is a metal plate that defines a receiver 1204, a plurality of apertures 1206, a cylindrical outer surface 1208, a cylindrical lip 1210, a rectangular cutout 1212, and a bore 1214. Receiver 1204 is configured to receive muzzle end 304 of barrel 102. In this particular example, receiver 1204 is an aperture that includes a female thread set 1216 that is configured to thread onto and off of complementary thread set 306 of barrel 102. Apertures 1206 pass completely through base 1200 to provide several functions including, but not limited to, providing an engagement feature for tools (e.g., a spanner wrench) that can be used to tighten guard 1102 onto barrel 102. As shown, apertures 1206 include three pairs of apertures. Each pair of apertures includes a first aperture and a second aperture that is disposed 180 degrees about axis 300 from the first aperture. Each of the three pairs of apertures has a different diameter than the other pairs. Cylindrical outer surface 1208 is configured to mate with a cylindrical inner surface 1218 of cage 1202. When outer surface 1208 of base 1200 is mated with inner surface 1218 of cage 1202, lip 1210 abuts the rear surface 1220 of cage 1202. With outer surface 1208 mated with inner surface 1218, base 1200 and cage 1202 are fixed together by, for example, a weld between lip 1210 and cage 1202. Optionally, cage 1202 may be removably connected to base 1200, so that cage 1202 can be removed from, and connected to, base 1200 while base 1200 is still connected to barrel 102. Rectangular cutout 1212 is configured to receive a spanner wrench used to tighten guard 1102 onto barrel 102. Bore 1214 is configured to receive a pin for permanently fixing guard 1102 to barrel 102, in a similar fashion as pins 602 of FIG. 6A-6D. Bore 1214 extends along an axis 1221 that perpendicularly intersects axis 300.

Cage 1202 is a metal tubular structure that extends forward from base 1200 along axis 300. The sidewall of cage 1202 defines a large passage 1222, through which an interior space 1224 and muzzle attachments disposed therein can be accessed by tools and the user's hands. Passage 1222 is large enough to put muzzle attachments through, so that the muzzle attachments don't have to be dropped through the open front end 1226 of guard 1102. Passage 1222 is also large enough to allow a wrench to turn a muzzle attachment at least 240 degrees about axis 300, with the handle of the wrench extending through side passage 1222 to the outside of cage 1202. Cage 1202 further defines a plurality of hexagonal passages 1228 that function as air vents through which hot air can exit cage 1202.

Cage 1202 is formed by cutting various passages through a strengthened metal tube. In this embodiment, the metal tube is 4130 steel. Optionally, the tube can be titanium, magnesium, aluminum, and alloys thereof. Cage 1202 may also be formed by cutting various openings in a tube of other materials such as, for example, heat resistant plastic, silicone, etc. Cage 1202 may also be formed via molding or casting materials such as, for example, heat resistant polymers such as silicone, metals, metal alloys, etc. As yet another example, cage 1202 can be formed of metal as described and then coated with or molded into a heat resistant material.

FIG. 13 shows a side plan view of guard 1102 aligned with axis 300. Side passage 1222 of cage 1202 is large enough to permit the passage of muzzle attachments therethrough and to allow a user to access interior space 1224 of cage 1202 with their hands and/or tools. For example, the first vertical distance (di) of passage 1222 is approximately 2.75 times greater than the second vertical distance (d2) between the top of passage 1222 and the top of cage 1202. The sum of the first vertical distance (d1) and the second vertical distance (d2) is equal to the overall vertical height (hv) of cage 1202. The horizontal distance (d3) of passage 1222 is approximately ⅔ the overall vertical height (hv) of cage 1202 and base 1200. The relative dimensions facilitate access to interior space 1224, while maintaining sufficient structural rigidity.

FIG. 14 shows a cross-sectional side view of guard 1102, taken along line E-E of FIG. 11, with guard 1102 and muzzle brake 800 mounted to muzzle end 304 of barrel 102. As previously mentioned, base 1200 includes a single bore 1214 extending along an axis 1400 that perpendicularly intersects axis 300. Bore 1214 is configured to receive a cylindrical pin for permanently attaching guard 1102 to muzzle end 304 of barrel 102. During the permanent fixing of guard 1102 to barrel 102, a drill bit is advanced along axis 1400, to cut slightly into barrel 102 and form a recess. Then, the pin is placed into bore 1214 and the top of pin is welded to base 1200. To remove guard 1102 from barrel 102 without damaging guard 1102 or barrel 102, the weld can be cut and the pin can be removed from bore 1214. With the pin removed, guard 1102 can be unscrewed off of barrel 102.

FIG. 15 and FIG. 16 show a rear perspective view and a front perspective view, respectively, of another example base 1500 aligned with axis 300. Base 1500 is a monolithic structure (e.g., a machined metal billet) defining a cylindrical end plate 1502, a receiver 1504, a cylindrical wall 1506, and a set of bores 1508. Receiver 1504 is an opening passing completely through end plate 1502 that is configured to receive muzzle end 304 of barrel 102. Receiver 1504 defines a female thread set 1510 that is configured to thread onto and off of complementary thread set 306 of barrel 102. When base 1500 is threaded onto barrel 102, a circular planar surface 1512 of end plate 1502 frictionally engages the shoulder portion of barrel 102 where threads 306 end and the non-threaded portion of barrel 102 begins. End plate 1502 also includes a cylindrical outer surface 1513 that mates with the interior surface 416 of cage 402 (or corresponding surface of an alternate cage). Cylindrical wall 1506 extends from the front surface of plate 1502, along axis 300, and includes an exterior surface defining a thread set 1514. In this example, thread set 1514 is a standard Hybrid Universal Base (HUB) mounting platform, which includes 1.375x24TPI thread specifications. These thread specifications are configured to receive standard HUB suppressors, but other thread specifications or other type of mechanical interface could be used instead. Bores 1508 are aligned along an axis 1516 and pass completely through plate 1502 such that axis 1516 perpendicularly intersects axis 300. Bores 1508 are configured to receive pins, such as pins 602, that are used to permanently fix base 1500 to barrel 102 via a weld between base 1500 and pin 602. When base 1500 is permanently fixed to barrel 102. It can be removed without damaging barrel 102 by cutting the weld and then unscrewing base 1500 from barrel 102. When base 1500 is attached to cage 402, bores 1508 coaxially align with respective apertures 418.

FIG. 17 shows a cross-sectional view of base 1500 taken along line F-F of FIGS. 15-16. As shown, receiver 1504 defines a non-threaded portion 1700 that has a slightly larger diameter than thread set 1510 so that portion 1700 can pass over thread set 306 of barrel 102 when base 1500 is screwed onto barrel 102. Optionally, thread set 1510 may be omitted and portion 1700 can extend all the way through base 1500. When thread set 514 omitted, base 1500 can be secured to barrel 102 by screwing a muzzle attachment onto barrel 102 such that end plate 1502 is sandwiched between the muzzle attachment and the shoulder portion of barrel 102 where thread set 306 ends and the non-threaded portion of barrel 102 begins.

FIG. 18 and FIG. 19 are a rear perspective view and a front perspective view, respectively, of another example base 1800 aligned with axis 300. Base 1800 is a monolithic structure (e.g., a machined metal billet) defining a cylindrical end plate 1802, a receiver 1804, a muzzle brake 1806, and a set of bores 1808. Receiver 1804 is an opening passing completely through end plate 1802 that is configured to receive muzzle end 304 of barrel 102. Receiver 1804 defines a female thread set 1810 that is configured to thread onto and off of complementary thread set 306 of barrel 102. When base 1800 is threaded onto barrel 102, a circular planar surface 1812 of end plate 1802 abuts the shoulder portion of barrel 102 where thread set 306 ends and the non-threaded portion of barrel 102 begins. Muzzle brake 1806 extends from the front surface of plate 1802 along axis 300 and defines a set of side-facing exhaust ports 1814 and a muzzle exit passage 1816. When a bullet is fired through barrel 102, exhaust gasses pass through ports 1814 and the bullet exits through passage 1816. Although only three exhaust ports 1814 are visible, muzzle brake 1806 includes six total exhaust ports, with three facing away from axis 300 in one direction and the other three facing away from axis 300 in an opposite direction. End plate 1802 includes a cylindrical outer surface 1818 that is configured to mate with complementary cylindrical inner surface 416 of a cage 402. Base 1800 may be fixed to a cage (i.e., cage 402, cage 1202) in the same fashion (e.g., welds, fasteners, mechanical engagement, compression fit, etc.) that bases 400 and 1200 are fixed to respective cages 402 and 1202. Bores 1808 are aligned along an axis 1820 and pass completely through plate 1802 such that axis 1820 perpendicularly intersects axis 300. Bores 1808 are configured to receive pins, such as pins 602, that are used to permanently fix base 1800 to barrel 102 by a weld between base 1800 and pin 602. When base 1800 is permanently fixed to barrel 102, it can be removed without damaging barrel 102 by cutting the weld and then unscrewing base 1800 from barrel 102.

FIG. 20 is a cross-sectional view of base 1800 taken along line G-G of FIGS. 18-19. Receiver 1804 defines a non-threaded portion 2000 that has a slightly larger diameter than thread set 1810, so that portion 2000 can pass over thread set 306 of barrel 102 when base 1800 is screwed onto barrel 102. As shown, thread set 1810 extends through both end plate 1802 and partially into muzzle brake 1806. However, as an alternative, thread set 1810 can be formed only in muzzle brake 1806 and not in end plate 1802.

FIG. 21 and FIG. 22 are a rear perspective view and a front perspective view, respectively, of another example base 2100 aligned with axis 300. Base 2100 is a monolithic structure (e.g., a machined metal billet) defining a cylindrical end plate 2102, a receiver 2104, a cylindrical wall 2106, a muzzle brake 2108, and a set of bores 2110. Receiver 2104 is an opening passing completely through end plate 2102 that is configured to receive muzzle end 304 of barrel 102. Receiver 2104 defines a female thread set 2112 that is configured to thread onto and off of complementary thread set 306 of barrel 102. When base 2100 is threaded onto barrel 102, a circular planar surface 2114 of end plate 2102 abuts the shoulder portion of barrel 102, where thread set 306 ends and the non-threaded portion of barrel 102 begins. End plate 2102 further includes a cylindrical outer surface 2115 that mates with the interior surface 416 of cage 402 (or other cage) when base 2100 is fixed to cage 402 (or other cage). Cylindrical wall 2106 extends from the front surface of plate 2102, along axis 300, and includes an exterior surface defining a thread set 2116. In this example, thread set 2116 is a standard HUB thread set, which includes 1.375x24TPI thread specifications. These thread specifications are configured to receive standard HUB suppressors. Different thread sets or other mechanical engagement means can be used to secure alternate muzzle attachments. Muzzle brake 2108 extends from the front surface of wall 2106, along axis 300, and defines a set of side facing exhaust ports 2118 and a muzzle exit passage 2120. When a bullet is fired through barrel 102, exhaust gasses pass through ports 2118, and the bullet exits through passage 2120. Although only two exhaust ports 2118 are visible in the drawings, muzzle brake 2108 actually includes four total exhaust ports, with two facing away from axis 300 in one direction and the other two facing away from axis 300 in an opposite direction. Bores 2110 are aligned along an axis 2121 and pass completely through plate 2102, such that axis 2121 perpendicularly intersects axis 300. Bores 2110 are configured to receive pins, such as pins 602, that are used to permanently fix base 2100 to barrel 102 by a weld between base 2100 and pin 602. After base 2100 is permanently fixed to barrel 102, it can be removed without damaging barrel 102 by cutting the weld and then unscrewing base 2100 from barrel 102. When base 2100 is attached to cage 402, bores 1508 coaxially align with respective apertures 418.

FIG. 23 is a cross-sectional view of base 2100, taken along line H-H of FIGS. 21-22. Receiver 2104 defines a non-threaded portion 2300 that has a slightly larger diameter than thread set 2112, so that portion 2300 can pass over thread set 306 of barrel 102 when base 2100 is screwed onto barrel 102. Base 2100 further defines a cylindrical recess 2302 formed symmetrically about axis 300, between receiver 2104 and wall 2106. Recess 2302 reduces the overall weight of base 2100.

FIG. 24 and FIG. 25 are a rear perspective view and a front perspective view, respectively, of another example base 2400 aligned with axis 300. Base 2400 is a monolithic structure (e.g., a machined metal billet) defining a cylindrical end plate 2402, a receiver 2404, a cylindrical wall 2406, and a set of bores 2408. Receiver 2404 is an opening passing completely through end plate 2402 that is configured to receive muzzle end 304 of barrel 102. Receiver 2404 defines a female thread set 2410 that is configured to thread onto and off of complementary thread set 306 of barrel 102. When base 2400 is threaded onto barrel 102, a circular planar surface 2412 of end plate 2402 frictionally engages the shoulder portion of barrel 102 where thread set 306 ends and the non-threaded portion of barrel 102 begins. End plate 2402 further includes a cylindrical outer surface 2414 that is configured to mate with a complementary cylindrical inner surface (e.g., surface 416, surface 1218) of a cage (e.g., cage 402, cage 1202). Base 2400 can be fixed to a cage (i.e., cage 402, cage 1202) in the same fashion (e.g., welds, fasteners, mechanical engagement, compression fit, etc.) that bases 400 and 1200 can be fixed to respective cages 402 and 1202. Cylindrical wall 2406 extends from the front surface of plate 2402, along axis 300, and includes an exterior surface defining a thread set 2416 that is configured to receive a muzzle attachment. In this example, thread sets 306, 2410, and 2416 all have the same thread specifications. Bores 2408 are aligned along an axis 2418 and pass completely through plate 2402, such that axis 2418 perpendicularly intersects axis 300. Bores 2408 are configured to receive pins, such as pins 602, that are used to permanently fix base 2400 to barrel 102 by a weld between base 2400 and pin 602. After base 2400 is permanently fixed to barrel 102, it can be removed without damaging barrel 102 by cutting the weld and then unscrewing base 2400 from barrel 102.

FIG. 26 is a cross-sectional view of base 2400, taken along line K-K of FIGS. 24-25. Receiver 2404 defines a non-threaded portion 2600 that has a slightly larger diameter than thread set 2410, so that portion 2600 can pass over thread set 306 of barrel 102 when base 2400 is screwed onto barrel 102. In this example, thread set 2410 receives the entire thread set 306 of barrel 102 such that thread set 2410 is not accessible from the front of base 2400. Instead, muzzle attachments are connected indirectly to barrel 102 by screwing them onto thread set 2416. In other words, base 2400 functions as a barrel extension that is configured to receive both a muzzle attachment and a cage (e.g., cage 402, cage 1202, or similar cage).

FIG. 27 is a bottom perspective view of another example shield 2700, which is configured to be selectively disposed around, and removed from, guard 312. Shield 2700 is formed from 0.006 in thick spring tempered 301 stainless steel, which is cut and bent into shape. Optionally, shield 2700 can be cut (e.g., laser cut) from a tubular section of 0.006 inch thick spring tempered 301 stainless steel. The spring properties of shield 2700 allow it to be urged open, disposed around guard 312, and then returned back to its original shape without permanent deformation. Shield 2700 is urged open by urging two opposing open edges 2702 away from one another. Each of edges 2702 includes a front tab 2704 and a longer rear tab 2706. Front tabs 2704 are configured to engage opposing side edges of the front, bottom passage 422 of cage 402, and rear tabs 2706 are configured to engage opposing side edges of the rear, bottom passage 422 of cage 402. Shield 2700 may also be rotated about cage 402 such that front tabs 2704 engage opposing side edges of the front, top passage 422 of cage 402 and rear tabs 2706 engage opposing side edges of the rear, top passage 422 of cage 402. Optionally, guard 312 can be tapered slightly, so that shield 2700 is urged open as it is pushed onto guard 312. Each of edges 2702 defines a relieved portion 2708 that provides an opening through which a user's hands and/or tools may be passed to access interior space 316 of cage 402.

FIG. 28 shows a bottom perspective view of another example shield 2800, which is configured to be selectively disposed around, and removed from, guard 312. Shield 2800 is substantially similar to shield 2700, except that shield 2800 has a plurality of hexagonal apertures 2802 formed through its sidewall to allow hot air to pass therethrough. Therefore, like features are denoted by like reference numbers and not described in detail to avoid redundancy. Shield 2800 may optionally include heat resistant cord (e.g., Kevlar cord) that is woven through apertures 2802 to eliminate direct contact with shield 2800, particularly when it heats up. To provide further burn protection and to mitigate the “mirage effect”, heat shield 314 of FIG. 3 may be removably disposed over either of shields 2700 and 2800.

FIG. 29 is a rear perspective view of another example cage 2900, which can be attached (e.g., welded, fastened, compression fit, threaded, integrally formed together, and so on) to any of the previously described bases to form a guard. Cage 2900 is a thin-walled steel tube that defines two side passages 2902. Each of side passages 2902 is formed on a respective side of cage 2900, 180 degrees apart about axis 300. Each of side passages 2902 also has the same dimensions, which are shown in FIGS. 30-32. Passages 2902 are large enough to allow a user's hand to grip opposing sides of a muzzle attachment disposed in an interior space 2904 of cage 2900. Cage 2900 further includes a rear end section 2906 that is configured to receive any one of the bases described herein.

FIG. 30 is a side plan view of cage 2900. As shown, the horizontal width of passages 2902 is 3.5 inches, and the vertical height of passages 2902 is 1.414 inches. The outside diameter of cage 2900 is 2.000 inches, and the overall horizontal width of cage 2900 is 7.000 inches. The horizontal width of section 2906 is 0.500 inches.

FIG. 31 is a cross-sectional side view of cage 2900 with a suppressor 3100 disposed in interior space 2904, taken along line J-J of FIG. 29. Each of passages 2902 extends 90 degrees about axis 300 within the YX plane of FIG. 29, between the top edges 3102 and bottom edges 3104 of passages 2902. The solid portions 3106 of cage 2900 also extends 90 degrees about axis 300 within the YX plane of FIG. 29, between the top edges 3102 and bottom edges 3104 of passages 2902.

FIG. 32 is a top plan view of cage 2900 with suppressor 3100 disposed in interior space 2904. Suppressor 3100 has an outside diameter of 1.500 inches, which is slightly greater than the 1.414 inch distance between top edges 3102, which bound solid portion 3106 of cage 2900. The distance between the each edge 3102 and the outside surface of cage 2900 is 0.293 inches. As shown, the outside edges of suppressor 3100 protrude slightly past edges 3102 such that a user can grasp each opposing side of suppressor 3100 with their hand and manipulate suppressor 3100 within interior space 2904 of cage 2900. For example, a user can grasp each opposing side of suppressor 3100 through passages 2902 and rotate suppressor 3100 about axis 300.

FIG. 33 is a rear perspective view of another alternate cage 3300 that may be attached (e.g., welded, fastened, compression fit, threaded, integrally formed together, and so on) to any of the bases described herein to form a guard. Cage 3300 is a thin-walled steel tube that defines two side passages 3302. Each of side passages 3302 is formed on a respective side of cage 3300, 180 degrees apart about axis 300. Each of side passages 3302 also has the same dimensions, which are shown in FIGS. 34-36. Passages 3302 are large enough to allow the passage of a tool therethrough. A tool may pass through one of passages 3302 to engage a muzzle attachment disposed in an interior space 3304 of cage 3300 or a tool may simultaneously pass through both passages 3302 to engage opposing sides of the muzzle attachment. Cage 3300 further includes a rear end section 3306 that configured to receive any one of the bases described herein.

FIG. 34 is a side plan view of cage 3300. As shown, the horizontal width of passages 3302 is 0.500 inches and the vertical height of passages 3302 is 1.414 inches. The outside diameter of cage 3300 is 2.000 inches and the overall horizontal width of cage 3300 is 7.000 inches. The horizontal width of section 3306 is 0.500 inches, which corresponds to an approximately 0.500 inch portion of a base that gets inserted and fixed into section 3306, such that when cage 3300 and a base are mounted to a firearm barrel, the threads of the muzzle end of the barrel are accessible and visible through passages 3302 before a muzzle attachment is threaded thereon.

FIG. 35 is a cross-sectional side view of cage 3300 with suppressor 3100 disposed in interior space 3304, taken along line K-K of FIG. 33. Each of passages 3302 extends 90 degrees about axis 300, within the YX plane of FIG. 33, between the top edges 3502 and bottom edges 3504 of passages 3302. The solid portions 3506 of cage 3300 also extend 90 degrees about axis 300, within the YX plane of FIG. 33, between the top edges 3502 and bottom edges 3504 of passages 3302.

FIG. 36 is a top plan view of cage 3300 with suppressor 3100 disposed in interior space 3304. Suppressor 3100 has an outside diameter of 1.500 inches, which is slightly greater than the 1.414 inch distance between top edges 3502, which bound solid portion 3506 of cage 3300. The distance between the each edge 3502 and the outside surface of cage 3300 is 0.293 inches. As shown, the outside edges of suppressor 3100 protrude slightly past edges 3502 such that a tool can access one or both opposing sides of suppressor 3100 and manipulate the position of suppressor 3100 within interior space 3304 of cage 3300.

FIG. 37 is a flowchart summarizing a method 3700 of permanently fixing a muzzle attachment guard to a firearm barrel. In a first step 3702, a firearm barrel is provided. Then, in a second step 3704, a guard is provided. Next, in a third step 3706, a pin is provided. Then, in a fourth step 3708, a bore is formed in the guard. Next, in a fifth step 3710, a recess is formed in the firearm barrel. Then, in a sixth step 3712, the guard is positioned on the muzzle end of the firearm barrel. Next, in a seventh step 3714, the pin is positioned in the bore and the recess. Finally, in an eighth step 3716, the pin is welded to the guard. Thus, the guard is considered to be permanently fixed to the muzzle of the firearm, because the guard cannot be removed from the muzzle by non-destructive means, such as with the use of common hand tools. However, the guard may be optionally removed from the muzzle of the firearm by destroying the weld between the pin and the guard.

The description of particular embodiments of the present invention is now complete. Many of the described features may be substituted, altered or omitted without departing from the scope of the invention. For example, alternate air vent shapes (e.g., round, elongated, etc.), may be substituted for the hexagonal air vents. As another example, the various guards and shields may be formed from various materials including, but not limited to, silicone, heat resistant polymers, ceramics, fiberglass, and so on. These and other deviations from the particular embodiments shown will be apparent to those skilled in the art, particularly in view of the foregoing disclosure.

Claims

1. A guard assembly for a muzzle attachment fixed to a muzzle of a firearm by an engagement mechanism of said muzzle of said firearm, said guard assembly comprising:

a base defining a receiver configured to receive said muzzle of said firearm; and

a guard extending from said base in a forward direction and at least partially surrounding a bore axis of said firearm, said guard defining an interior space, wherein said muzzle attachment is disposed; and wherein

said guard defines a first passage extending from outside of said guard to said interior space of said guard; and

said first passage has a first dimension measured along a direction parallel to said bore axis and a second dimension measured in a plane perpendicular to said bore axis, said first dimension being sufficient to permit a tool to pass through said first passage and engage said muzzle attachment, and said second dimension being sufficient to facilitate rotation of said tool in said plane and about said bore axis.

2. The guard assembly of claim 1, wherein:

said base further defines a bore extending in a direction perpendicular to said bore axis of said firearm from an outer edge of said base into said receiver;

said guard defines an aperture aligned with said bore; and

said guard assembly further includes a pin configured to be permanently fixed in said bore in engagement with said muzzle of said firearm, to permanently fix said guard assembly to said muzzle of said firearm.

3. The guard assembly of claim 1, wherein said receiver defines a cylindrical opening configured to engage a complementary cylindrical surface of said muzzle of said firearm.

4. The guard assembly of claim 3, wherein said cylindrical opening includes a first thread set configured to engage a complementary second thread set on said cylindrical surface of said muzzle of said firearm.

5. The guard assembly of claim 4, wherein said engagement mechanism of said muzzle remains accessible when said muzzle is received by said receiver.

6. The guard assembly of claim 1, wherein said guard is rigidly fixed to said base.

7. The guard assembly of claim 1, wherein said base is disposed within an inch of a second plane perpendicular to said bore axis and passing through said first opening.

8 The guard assembly of claim 7, wherein said second dimension of said first passage subtends an angle of at least 60 degrees at said bore axis.

9. The guard assembly of claim 8, wherein said second dimension of said first passage subtends an angle of at least 90 degrees at said bore axis.

10. The guard assembly of claim 9, wherein said second dimension of said first passage subtends an angle greater than 180 degrees at said bore axis.

11. The guard assembly of claim 1, wherein said first passage is large enough to facilitate the passage of said muzzle attachment.

12. The guard assembly of claim 1, wherein:

said guard additionally defines a second passage extending from outside of said cage to said interior space of said cage, said second passage including a third dimension measured along a direction parallel to said bore axis and a fourth dimension measured in a plane perpendicular to said bore axis;

said second passage is disposed on an opposite side of said guard from said first passage;

said second dimension of said first passage subtends an angle of at least 60 degrees at said bore axis; and

said fourth dimension of said second passage subtends an angle of at least 60 degrees at said bore axis.

13. The guard assembly of claim 12, wherein:

said second dimension of said first passage subtends an angle of at least 90 degrees at said bore axis; and

said fourth dimension of said second passage subtends an angle of at least 90 degrees at said bore axis.

14. The guard assembly of claim 13, wherein said first passage and said second passage are symmetrical about said bore axis.

15. The guard assembly of claim 1, wherein:

said base includes a plate having a cylindrical outer surface;

said guard includes a shell having cylindrical inner surface that mates with said cylindrical outer surface of said base plate.

16. The guard assembly of claim 15, wherein:

said guard includes a cylindrical shell having a wall that defines said first passage;

said cylindrical shell has a first end fixed to said base;

said cylindrical shell includes a second end opposite said first end; and

said second end includes an opening with a peripheral edge, said peripheral edge including a first segment, a second segment, a third segment, and a fourth segment;

said second segment is disposed between said first segment and said third segment;

said first segment is disposed between said second segment and said fourth segment;

said first segment and said third segment are disposed on a first side of a second plane perpendicular to said bore axis; and

said second segment and said fourth segment are disposed on an opposite side of said second plane.

17. The guard assembly of claim 1, further comprising a heat shield disposed at least partially around said guard.

18. The guard assembly of claim 17, wherein said heat shield defines at least one opening through said heat shield.

19. The guard assembly of claim 17, wherein said heat shield is made of spring steel.

20. The guard assembly of claim 17, wherein said heat shield is selectively removable from said guard.

21. The guard assembly of claim 20, wherein said heat shield includes at least one tab configured to engage at least one opening of said guard.