Adjustable Gas Block
An adjustable gas block designed to interface with the gas-operating system of an auto-loading firearm. This design provides continuously adjustable gas flow, from fully closed to fully open, in small, discrete, uniform, and fully-repeatable increments. The design works by means of a click adjustment valve screw which has a number of grooves that are engaged by a spring-loaded detent. As the screw is turned in or out, either by a tool or by an integrated finger-adjustable knob or handle, the clicks of the detent provide both audible and tactile feedback to the user. This allows a user to optimize the operation of a firearm by responding to variations in ammunition loading, bullet weight, atmospheric temperature, cartridge caliber, and for the installation/removal of a silencer, each of which changes the volume and pressure characteristics of the gas-operating system.
This application claims the benefit of provisional patent application No. 61/550,569, filed 2011 Oct. 24 by the present inventor.
FEDERALLY SPONSORED RESEARCHNot Applicable.
SEQUENCE LISTINGNot Applicable.
BACKGROUND-FIELD OF INVENTIONThis invention relates to gas-operated auto-loading firearms, and specifically to user-adjustable gas blocks for such firearms.
BACKGROUND-PRIOR ARTA gas block for an auto-loading firearm is a device that is placed usually on the barrel of an auto-loading firearm, and used as a means to tap, collect, restrict, and direct the flow of propellant gas from the firearm's barrel into the auto-loading mechanism so as to provide the necessary energy to operate the auto-loading firearm. Adjustable gas blocks have been used on military auto-loading firearms for decades, as seen in such firearms as: the Soviet SVD; Yugoslavia's models 70, 76, and 95; the Belgian FAL; and recent Belgian SCAR rifles. In addition, some commercially sold rifles, such as the AR10 SASS and variants like the JP Enterprises LRT 07, also use some form of adjustable gas block technology.
Early adjustable gas blocks were used to help minimize wear of the firearm by providing only enough gas to properly operate the firearm's auto-loading mechanism. Another application was to adapt the firearm to fire rifle-mounted grenades, with the use of a special cartridge. Some early adjustable gas blocks, such as the Yugoslav design, were also used to compensate for different ammunition or extreme fouling build-up under battlefield conditions, when complete cleaning was not practical. These early designs typically had only two or three settings, and were usually adjusted by movement of a drum valve with different sized ports drilled in it, which were aligned with a corresponding port that communicated with the auto-loading mechanism. By turning the drum so as to align a smaller or larger port, the amount of propellant gas allowed into the operating system could be regulated (reduced or increased) in a limited way. More recent variations of the drum-type valve have been used to compensate for the installation or removal of a silencer.
Historically, there are three basic adjustable gas block designs:
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- 1. The drum valve version. In this design, the drum valve, itself, resides either in or in front of the gas tube on an M16/AR15/AR10/M4 type firearm; or in front of the gas cylinder, in the case of a piston-driven mechanism. This design is exemplified by the AR10 SASS and Yugoslav designs cited above, and more recently by the Noveske patent (U.S. Pat. No. 7,856,917 B2).
- 2. The set screw adjustable version. This design uses a common socket head set screw as a valve screw that can be continuously adjusted in and out to occlude, to a varying amount, the passageway between the barrel and the gas tube or gas cylinder. This design has been adapted to M16/AR15/AR10/M4 type firearms, and is sold by vendors such as Brownells, Inc. of Montezuma, Iowa.
- 3. The vent cover version. This design is exemplified by the Belgian FAL, and uses a nut, placed on the outside of a threaded gas cylinder, to cover or uncover more or less of the area of a hole drilled through the cylinder, thus venting more or less gas to the atmosphere.
The drum valve design has three inherent disadvantages. First is the very limited range of adjustment settings, typically two or three. These settings are usually comprised of fully closed, fully open, and one setting in between (typically engineered for a specific purpose). Second is the large surface areas of the mating parts (comprising the drum valve itself and the cylinder inside which it rotates). These surfaces are subject to buildup of carbon fouling from the propellant gas. After as few as 200 rounds have been fired, the valve can be rendered immovable without the use of large, and seldom field-available, tools. Third is the fixed-size orifices of the drum. These predetermined sizes are not adaptable to such field variables as: wear of the mating parts; wear of the rest of the firearm's operating system; the sometimes wide variation in working pressure of the ammunition in use; or other unforeseen field variables.
The prior art valve screw design, making use of a common socket head set screw to occlude the port between the barrel and the gas tube on M16/AR15/AR10/M4 type firearms, has two significant disadvantages. First is that nothing holds the screw in adjustment. An expedient remedy for this shortcoming is to apply a commercial thread-locking compound, such as Loctite, to the adjustment screw's threads. However, this action creates another problem: with the screw head locked in place, the extremely small hex wrench, used for adjustment, only serves to strip out the hex socket in the screw's head, thus rendering the screw removable only after extensive disassembly of the firearm. The second disadvantage of this design is that the adjustments are not precisely repeatable. A user may effectively adjust the valve for one set of circumstances, change it for another set of circumstances, but be unable, without long experimentation and expenditure of ammunition, to return to the first setting.
The vent cover design, as used on the Belgian FAL, has two major disadvantages. First, by directly venting excess gas to the atmosphere, this design negates the use of a silencer; a vented blast and flash makes a silencer ineffective. Second, this design is only usable in piston-driven auto-loading firearms. Direct impingement systems, as are used on M16/AR15/AR10/M4 type firearms, have no external gas cylinder on which such a design could be used.
ADVANTAGES OF THE INVENTION OVER PRIOR ARTThe present invention uses a continuously adjustable valve screw. Not limited to two or three settings, the valve screw can be easily adjusted to any setting between fully open and fully closed, with a number of discrete and fully repeatable adjustment settings in-between. This means the firearm's gas-operated auto-loading mechanism can now be quickly adjusted for differences in ammunition loading, bullet weight, atmospheric temperature, cartridge caliber, and for the installation/removal of a silencer. This gas block adjustment mechanism does not vent excess gas, or its consequent noise and flash, to the atmosphere. Both are undesirable characteristics when a firearm is sound-suppressed.
The present invention uses a click adjustment valve screw offering precisely repeatable and recordable settings, or clicks. Adjustments can be precisely repeated by simply counting clicks down from fully open or up from fully closed. This process is very much like adjusting sight settings, something with which most users are already familiar.
Embodiments of the present invention use a detent mechanism to engage grooves in a click adjustment valve screw that positively retains the user's adjustment setting, eliminating the need for a thread-locking compound.
Embodiments of the present invention use a click adjustment valve screw with a larger socket head, enabling the use of a larger size wrench, or, in another embodiment, a finger-manipulable knob, neither of which are prone to stripping out. Incorporating a coin slot in the finger-manipulable knob, to facilitate manual adjustment, is yet another embodiment of the present invention.
Embodiments of the present invention can be adjusted by using a larger size wrench or finger-manipulable knob via an access port provided in the side of an extended fore-end. Alternately, embodiments of the present invention could have the adjustment apparatus oriented in such a way as to be accessed from the open front end of an extended fore-end. The installation of an extended fore-end is increasingly popular on carbines and other short-barreled rifles, and serves to protect users' hands from being burnt by a hot barrel.
In addition, the present invention's precisely and finely adjustable increments have led to the discovery of several unforeseen advantages. 1.) The click adjustment valve screw can now be used as a barrel tuner, and highly accomplished marksmen can use it to enhance the inherent accuracy of their firearm. 2.) The gas-operating system can now be finely tuned to the installation of a silencer and its resultant increase in back pressure and fouling, compensating to the point where the additional fouling caused by this back pressure is all but eliminated. This can make a positive improvement in field reliability, and serve to reduce maintenance requirements of a given firearm. 3.) It has been found that when a click adjustment valve screw is adjusted to its optimal setting—of two clicks more open than are required to just lock back the bolt on an empty magazine—the firearm's cyclic rate is reduced during fully automatic fire. This makes the firearm much more user-controllable during fully automatic fire. 4.) The inevitable carbon buildup, in the threads of a click adjustment valve screw, does not jam or otherwise render the adjustment mechanism unusable. To the contrary, it actually seems to act as a lubricant.
SUMMARYProvided is an adjustable gas block for a gas-operated auto-loading firearm, also referred to herein as an improved adjustable gas block. The improved adjustable gas block has a main housing manufactured of metal or other suitable material, longitudinal bores for the firearm's barrel and gas tube or cylinder, and a gas transfer port connecting those two bores. The gas transfer port is transversely intersected by a click adjustment valve screw which incorporates a spring-driven detent mechanism to hold the click adjustment valve screw in place when adjusted to any position from fully open to fully closed. Both the fully open position and the fully closed position are provided with positive mechanical stops. By counting detent “clicks” from either fully open or fully closed, a user can easily return the click adjustment valve screw to a pre-determined setting, and compensate for field variables such as: ammunition loading, bullet weight, atmospheric temperature, cartridge caliber, and for the installation/removal of a silencer. Adjustments can be made in precise, uniform, repeatable clicks, each of which accounts for a small incremental change in the amount of propellant gas allowed into a host firearm's gas-operating system, and is thus adaptable to a wide variety of field variables, as well as to many types of gas-operated auto-loading firearms. Adjustments may be made to a click adjustment valve screw either by use of a separate tool or a finger-manipulable knob, attached or integral, which may have a slot fitted for a coin or screwdriver.
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- 1 Complete assembly of an embodiment of an improved adjustable gas block
- 2 Main housing of an embodiment of an improved adjustable gas block (which can be of different shapes to serve specific functions)
- 4 Detent mechanism assembly
- 5 Detent element
- 5a Detent ball
- 5b Detent pin
- 6 Detent spring
- 7 Detent mechanism retention screw
- 8 Retention screw for click adjustment valve screw
- 10 Click adjustment valve screw
- 12 Gas flow adjustment end
- 12a Shaped end
- 12b Squared end
- 14 Valve screw drive method
- 14a Hex socket head
- 14b Finger-manipulable knob
- 16 Threads on click adjustment valve screw
- 18 Detent grooves in click adjustment valve screw
- 20 Extension, which may be threaded or unthreaded, of the hole for the click adjustment valve screw in main housing
- 21 Threaded hole in main housing for click adjustment valve screw
- 22 Countersink in main housing for head of valve screw
- 23 Through hole in main housing for detent element and spring
- 24 Bore in main housing for gas tube
- 26 Longitudinal bore in main housing for barrel
- 28 Blind hole in main housing for detent element and spring
- 29 Gas transfer port in main housing, through which propellant gas moves from barrel gas port to factory gas tube inlet port
- 32 Common hex key tool for adjusting click adjustment valve screw
- 34 Apparatus to secure improved adjustable gas block to barrel of host firearm
- 34a Common socket head set screws
- 34b Clamp mechanism
- 40 M16/AR15/AR10/M4 type firearm
- 42 Firearm receiver (combined upper and lower firearm receiver)
- 44 Firearm gas tube as supplied by factory
- 46 Firearm barrel
- 48 Standard length fore-end
- 50 Extended length fore-end
- 52 Access port in extended fore-end to enable adjustment of click adjustment valve screw
- 54 Common roll pin used to secure gas tube to gas block
- 58 Silencer of any brand or type
- 62 Gas port in factory firearm barrel
- 64 Firearm barrel bore
- 66 Factory gas tube inlet port
- 68 Internal bore of factory gas tube
An auto-loading firearm's gas-operating system is one which utilizes a portion of the firearm cartridge's propellant gas as the energy source to operate the firearm's auto-loading mechanism. The illustrated embodiments of the invention are designed to provide users of gas-operated auto-loading firearms with a means of precisely and repeatably adjusting the amount of gas which is allowed to pass from the barrel of a host firearm into its gas-operating system, thus providing the ability to optimize the operation of a firearm by compensating for variations in ammunition loading, bullet weight, atmospheric temperature, cartridge caliber, and for the installation/removal of a silencer. The term “gas-operated auto-loading firearm” as used in this document includes, but is not limited to, direct impingement systems such as M16/AR15/AR10/M4 type of firearms, as well as firearms that utilize a piston and cylinder in their gas-operating system. Please note that while the illustrated embodiments depict installation on an M16/AR15/AR10/M4 type firearm, the essential features of the herein described invention are not limited to these types of firearms or gas-operating systems.
Turning to the drawings, in which like reference numerals indicate corresponding elements throughout the several views, attention is directed to
An embodiment of an improved adjustable gas block 1 is intended as a replacement for a standard fixed-port gas block, well known in the prior art, and is for use on an auto-loading firearm 40. In this embodiment, an improved adjustable gas block 1 is designed to utilize the standard gas tube 44 and attachment roll pin 54 used in M16/AR15/AR10/M4 type firearms. This is shown in the exploded view in
Turning now to
Four versions of a click adjustment valve screw 10 are shown in
A click adjustment valve screw 10 seals off the flow of gas when in the fully closed position.
Irrespective of design version, an embodiment of a click adjustment valve screw 10 can be rotated a number of turns from fully open to fully closed. When fully open, it provides the amount of gas to the firearm's operating system that a normal factory-supplied fixed-port gas block would allow. When fully closed, it provides no gas at all to the operating system, and the auto-loading mechanism of the firearm will not function. In the fully closed position, the firearm can still be manually cycled. (
The concept of gas passageway interconnectivity is described in the following paragraph and depicted in several figures. First, as seen in the exploded view of
The concept of gas flow regulation is discussed here and diagrammatically illustrated in
In
Additionally, a click adjustment valve screw 10 in an improved adjustable gas block 1 can also be employed to compensate for the conversion of a host firearm to a completely different caliber than that for which it was originally designed.
It is useful to note at this point that when an embodiment of an improved adjustable gas block 1 is in the fully open position, the factory amount of gas is allowed to pass through the barrel gas port 62 and into the gas tube 44 via the gas tube inlet port 66 in said gas tube.
The longitudinal bore 26 (shown in
Upon installation of an improved adjustable gas block 1 on a host firearm 40, a user could follow this procedure to find the optimal initial setting for an improved adjustable gas block's 1 click adjustment valve screw 10:
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- 1. Turn the click adjustment valve screw 10 all the way open until it touches the retention screw 8. The improved adjustable gas block 1 now delivers as much gas to the gas-operating system as the factory barrel gas port 62 will allow.
- 2. Load one cartridge only in the magazine. Fire the single round and confirm that the bolt locks back on the empty magazine. If it does not, check installation and port alignment.
- 3. If it does, turn the click adjustment valve screw 10 one click closed and repeat step 2. Repeat this procedure until the bolt does not lock back, then open the click adjustment valve screw 10 two clicks and confirm the firearm's functionality. If any stoppages are detected, open the click adjustment valve screw 10 one more click and re-check function. Count the number of clicks required to open the click adjustment valve screw 10 until it touches the retention screw 8. Record the setting. (A user could choose to count up from fully closed, as well as down from fully open.)
By recording settings for previously-tested conditions or installed equipment, a user could quickly optimize a firearm's performance in response to changes in field conditions or equipment by adjusting a click adjustment valve screw 10 to a pre-determined setting. If, for example, a silencer is installed, a click adjustment valve screw 10 would be turned a predetermined number of clicks toward the closed position to compensate for the increased back pressure within the firearm's gas-operating system. Tactile and audible feedback indicates the screw's position, with each click opening/closing the firearm's gas port in small, uniform, discrete, and repeatable increments. By counting clicks down from fully open or up from fully closed, an embodiment of an improved adjustable gas block can be precisely returned to a given setting—even in the dark.
CONCLUSIONS, RAMIFICATIONS, AND SCOPEAccordingly, the reader will see that an improved adjustable gas block as described herein is a novel and useful invention with widespread application in gas-operated auto-loading firearms.
Claims
1. An improved adjustable gas block for a gas-operated auto-loading firearm, the firearm having a receiver with a forward end, a barrel with a gas port, and a gas tube with a gas inlet port, the barrel and gas tube joined to the receiver forward end, and the improved adjustable gas block comprising:
- a) a gas block housing manufactured of a suitable material with an apparatus to secure the gas block to the barrel, the gas block housing having a longitudinal bore extending through the housing to receive the firearm barrel, and having a second bore parallel to the first bore and extending a predetermined distance and adapted to receive the firearm's gas tube,
- b) the gas block housing also including a gas transfer port, further defined as aligned with both the barrel gas port and the gas tube inlet port, which when unobstructed permits the flow of propellant gas from the barrel gas port through the gas transfer port into the gas tube inlet port and thence to the firearm receiver, so as to operate the firearm's auto-loading mechanism,
- c) the gas transfer port being transversely intersected by a click adjustment valve screw with a distance of travel sufficient to render the gas transfer port either entirely open to the unhindered passage of propellant gas or entirely closed so as to completely prevent the flow of gas,
- d) the click adjustment valve screw further, having an area larger in diameter than the threaded body, and having evenly spaced grooves manufactured in said area parallel with the axis of the screw shank, said grooves being engaged by a spring-driven detent mechanism, being able thereby to be adjusted, either by use of a tool or a finger-manipulable knob, so as to be in a number of discrete positions between fully open and fully closed, the detent mechanism holding the click adjustment valve screw in a precise, repeatable setting.
2. The adjustable gas block of claim 1 embodied in a front sight.
3. The adjustable gas block of claim 1 embodied in a gas block with an integral accessory rail.
4. The adjustable gas block of claim 1 further comprising a click adjustment valve screw with a finger-manipulable knob or handle.
5. The adjustable gas block of claim 1 further comprising a click adjustment valve screw with a finger-manipulable knob or handle which also has a slot fitted for a coin or screwdriver.
6. The adjustable gas block of claim 1 wherein the click adjustment valve screw has a shaped end.
7. The adjustable gas block of claim 1 wherein the click adjustment valve screw has a squared end.
8. The adjustable gas block of claim 1 wherein the detent element is spherical in shape.
9. The adjustable gas block of claim 1 wherein the detent element is a pin.
10. The adjustable gas block of claim 1 wherein a mechanism is provided to prevent the click adjustment valve screw from being inadvertently removed during use, and said mechanism also acts as a positive stop for the click adjustment valve screw when it is in the fully open position.
11. An improved adjustable gas block for a gas-operated auto-loading firearm, the firearm having a barrel with a gas port, a receiver with a forward end, and a gas cylinder with a gas inlet port, the barrel and gas cylinder joined to the receiver forward end, the gas cylinder also containing a gas piston, and the improved adjustable gas block comprising:
- a) a gas block housing manufactured of a suitable material with an apparatus to secure the gas block to the barrel, the gas block housing having a longitudinal bore extending through the housing to receive the firearm barrel, and having a second bore parallel to the first bore and extending a predetermined distance and adapted to receive the firearm's gas cylinder,
- b) the gas block housing also including a gas transfer port, further defined as aligned with both the barrel gas port and the gas cylinder inlet, which when unobstructed permits the flow of propellant gas from the barrel gas port through the gas transfer port into the gas cylinder, thus initiating the motion of the gas piston which, in turn, operates the auto-loading mechanism of the firearm,
- c) the gas transfer port being transversely intersected by a click adjustment valve screw with a distance of travel sufficient to render the gas transfer port either entirely open to the unhindered passage of propellant gas or entirely closed so as to completely prevent the flow of gas,
- d) the click adjustment valve screw further, having an area larger in diameter than the threaded body, and having evenly spaced grooves manufactured in said area parallel with the axis of the screw shank, said grooves being engaged by a spring-driven detent mechanism, being able thereby to be adjusted, either by use of a tool or a finger-manipulable knob, so as to be in a number of discrete positions between fully open and fully closed, the detent mechanism holding the click adjustment valve screw in a precise, repeatable setting.
12. The adjustable gas block of claim 11 embodied in a front sight.
13. The adjustable gas block of claim 11 embodied in a gas block with an integral accessory rail.
14. The adjustable gas block of claim 11 further comprising a click adjustment valve screw with a finger-manipulable knob or handle.
15. The adjustable gas block of claim 11 further comprising a click adjustment valve screw with a finger-manipulable knob or handle which also has a slot fitted for a coin or screwdriver.
16. The adjustable gas block of claim 11 wherein the click adjustment valve screw has a shaped end.
17. The adjustable gas block of claim 11 wherein the click adjustment valve screw has a squared end.
18. The adjustable gas block of claim 11 wherein the detent element is spherical in shape.
19. The adjustable gas block of claim 11 wherein the detent element is a pin.
20. The adjustable gas block of claim 11 wherein a mechanism is provided to prevent the click adjustment valve screw from being inadvertently removed during use, and said mechanism also acts as a positive stop for the click adjustment valve screw when it is in the fully open position.
Type: Application
Filed: Jun 10, 2012
Publication Date: Apr 25, 2013
Inventor: Ralph J. Reinken (Boise, ID)
Application Number: 13/492,899
International Classification: F41A 5/28 (20060101); F41C 27/00 (20060101); F41G 1/02 (20060101);