Adjustable Volume Piston System

Abstract

An adjustable volume gas piston system for a pneumatic reloading firearm includes a gas block having an anchoring portion for anchoring along the barrel. The gas block also includes a chamber portion in pneumatic connection with the barrel. The chamber portion has one end pointing toward the muzzle and another end pointing away from the muzzle. A plug having a bore is affixed to the chamber portion at the forward end. The second end has an opening to allow travel of a gas pin but retains a gas pin head in the chamber portion, biasing it toward the first end. Upon firing the firearm, the volume of the bore causes a pressure delay on the gas pin head, thereby delaying the timing of pneumatic reloading.

Description

This application claims the benefit of the priority filing date of U.S. provisional application No. 61/920,454, filed on Dec. 23, 2013.

BACKGROUND

Gas-operated automatic reloading systems for firearms are known in the art. Typically, these systems divert a portion of high pressure gas generated from firing, using it to eject the bullet casing and chamber a new cartridge. Gas blocks are used to control the portion of gas used by the reloading system. Since unregulated pressure can destroy firearm components, gas blocks limit the amount of gas traveling into the reloading system to a predetermined level. Some gas blocks are adjustable, allowing users to change the quantity of gas as firing characteristics change due to altering the type of ammunition, or carbon and other material building up in the firearm form repeated firing.

Typical gas-operated automatic reloading systems port highly pressurized gas through a gas block and tube, bringing it to impinge directly on the bolt carrier, providing the energy necessary for the carrier to eject the spent casing and chamber a new cartridge. These direct impingement systems must be cleaned frequently. Gasses generated from firing have high concentrations of carbon, sulfates, and other materials that form accretions on firearm parts, adversely affecting firing characteristics.

Gas piston automatic reloading systems are used as an alternative to avoid contaminating the parts of the firearm. Piston systems employ a gas piston (also known as a ‘gas pin’) that bridges the gas block and the upper receiver. Upon firing, gas travelling into the gas block impinges immediately on a piston head of the gas pin, pushing the gas pin into the receiver to activate the reloading action. In this manner, gas piston systems avoid fouling internal components of the firearm, but can present a timing problem.

When a cartridge is fired, extremely high temperature and pressure gas generated between the bullet and the casing cause the casing to deform and swell in the chamber. Using softer, thermal conducting metals such as brass for casings help prevent them from lodging in the chamber, but require a brief dwell time allowing a spent casing to cool and shrink before it can be ejected. In direct impingement systems, the brief lag as sufficient pressure builds across the system to move the bolt carrier provides sufficient dwell time. In gas piston systems, the immediacy of the gas acting on the piston head and resulting mechanical reloading movement sometimes fails to allow sufficient dwell time, resulting in a jammed system.

It is therefore an object of the present invention to provide a gas piston system that avoids residue contamination from firing gases, but also provides sufficient dwell time to avoid malfunctions. Another object of the invention is to provide an adjustable volume gas block that allows a user to adjust the dwell time of the reloading system to a desired timing. Another object of the invention is to provide an adjustable volume gas block integrating dwell time adjustments and gas pressure adjustments. These and other objects are more fully developed in the following description claim and drawings.

SUMMARY

An adjustable volume gas piston system for a pneumatic reloading firearm, preferably having an elongated barrel with a muzzle is disclosed. The primary component of the system is a gas block. The gas block includes an anchoring portion that anchors along the barrel, preferably surrounding the barrel. Anchoring pins may be included at the bottom of the anchoring portion in one embodiment, and in another, notches on the barrel may ensure the anchoring portion stays in position.

The gas block also includes a chamber portion, preferably above the anchoring portion. The chamber portion is in pneumatic connection with the barrel, allowing gasses from firing the firearm to travel from the interior of the barrel into the chamber portion. Preferably, the chamber portion has a first end toward the muzzle and a second end away from the muzzle. In this manner, the chamber is oblong, oriented in the direction and at the position of a gas pin of the reloading system.

The first end of the chamber portion is open and adapted to receive a plug. The plug includes a bore and is therefore predominantly hollow, thereby forming a chamber in the chamber portion. The plug is affixed to the chamber at the first end in a manner that prevents it from becoming dislodged when the firearm is fired. The second end includes an opening that receives the gas pin. The gas pin preferably includes a gas pin head that is retained in the chamber portion, in one embodiment because the gas pin head is to large to travel through the opening, and biased toward the first end. A spring located in the chamber portion between the opening and the gas pin head may serve as a biasing mechanism.

Upon firing the firearm, the volume of the bore produces a pressure delay on the gas pin head. The delayed pressure results in a slight timing differential between firing and activation of the gas pin and pneumatic reloading. An important feature of the chamber portion of the gas block is that it is adjustable, thereby rendering the volume of the chamber portion and the timing differential adjustable. The principal way this adjustability is accomplished is by rendering the plug able to move relative to the chamber portion. In one embodiment the plug has threads that rotatably engage complimentary threads on the chamber portion. In this embodiment, the plug may closely resemble a screw having a head for engaging a fastening mechanism that turns the plug, a series of threads near the shoulder of the head, and an enlarged hollow plug body that forms part of the chamber in the chamber portion.

Adjusting the position of the plug relative to the chamber portion changes the volume of the chamber portion. Because the plug is movable, and due to pressures created by vibration and pressurized gas entering the chamber portion, over the course of firing several rounds the plug may have a tendency to change its orientation, thereby altering the volume of the chamber portion. To solve this problem, the plug preferably includes a biased stop mechanism to preserves the plug's position and thereby the volume of the chamber portion after positioning the plug to create a predetermined volume.

Preferably the biased stop mechanism is a bearing pressed into a biased position on the plug and a complimentary seat for the bearing on the gas block. In one embodiment, for ease of manufacturing, a bore is created through the head of the plug. The bore is sized to accommodate a bearing cylinder. The bearing is retained in the cylinder along with a spring that pushes the bearing to an open end of the cylinder. By inserting the cylinder a certain distance into the bore, a hemispherical portion of the bearing will extend away from the head of the bore.

In this embodiment, the gas block includes a screw set adjacent the plug head. The screw set includes a seat to receive the bearing. In this manner, as the plug head and bearing are rotated causing the bearing to encounter the screw set, the bearing will ‘snap’ into the seat, thereby retaining the plug in its position. In another embodiment the timing of the threads on the plug may be set so that when the plug is adjusted to its maximum point of insertion into the chamber portion, the bearing aligns with the seat.

When loosening the plug to adjust the volume of the chamber portion and the timing of the automatic reloading system, the bearing will periodically seat in the screw set, allowing users to set the gas block at a variety of pressures. In order to provide a safety, should firing vibration and pressure cause the bearing to unseat itself from its position, the screw set may include a second seat for catching the bearing and holding it in position prior to adjustment by a user.

The bore in the plug accounts for part of the gas chamber in the chamber portion. The remainder of the chamber is made up of the gas pin head and any space between the plug and the gas pin head. In one embodiment, the gas pin head may be biased to abut the plug. Preferably, the relationship between the chamber portion and the gas pin head is not a pneumatic seal and some minimal quantity of gasses are capable of travelling past the gas pin head upon firing. To introduce turbulence into gas travelling along the gas pin head, circumferential channels may be incorporated into the gas pin head. In another embodiment, the gas pin head may have a concave surface facing the bore to enlarge the chamber.

The gas pin head is locked into the chamber portion by an opening in the second end that only permits travel of the shaft of the gas pin. Preferably, the opening may include smaller cut-outs or other openings to allow gasses to pass between the gas pin head and the chamber portion, thereby exiting out the second end. The cut-outs or openings on the second end are not the primary exit for gasses produced by firing however. In one preferred embodiment, an exhaust port may be located direction on the chamber portion.

Typically the exhaust port will be obscured by the gas piston head prior to firing, either covered by the gas piston head itself, or located between the gas piston head and the second end. When the gas piston head is pushed toward the second end upon firing, the gas piston head will clear the exhaust port allowing pressurized gasses to exit the gas block. The other means for gas to exit the gas block is to travel back down into the barrel. To adjust the gas quantity and pressure travelling into the gas block upon firing, the gas block may also include an impinging screw between the barrel and the chamber portion for closing the pneumatic connection.

In order to adjust an automatic reloading firearm, including a gas pin and barrel, a gas block is first provided, the gas block having an anchoring portion and also having a chamber portion that defines a chamber. The gas block is installed on the barrel in a manner providing a pneumatic communication through the gas block between the chamber and the barrel. The chamber is preferably open at an end toward the barrel muzzle, and a plug having a bore is inserted into the open end of the chamber. Preferably the bore in the plug also defines a chamber. Prior to inserting the plug, a user preferably inserts a gas pin having a gas pin head into the chamber, such that the shaft of the gas pin extends through an opening in a second end of the chamber portion opposite the first end. Once the gas pin and plug are adjusted, the firearm may be fired, thereby causing a delay in the automatic reloading action of the gas pin.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view of a first embodiment adjustable volume gas block installed on a firearm.

FIG. 2 is a perspective view of an adjustable volume gas block installed on the firearm barrel.

FIG. 3 is an exploded view of a post screw and washers.

FIG. 4 is a cut-away view of an adjustable volume gas block with an expanded chamber volume.

FIG. 5 is a cut-away view of an adjustable volume gas block with a reduced chamber volume.

FIG. 6 is an exploded view of the first embodiment adjustable volume gas block.

FIG. 7 is a side view of a second embodiment gas block and gas piston system installed on an automatic reloading firearm.

FIG. 8 is an enlarged side view of the second embodiment gas block.

FIG. 9 is a perspective view of a chamber screw according to the second embodiment.

FIG. 10 is a perspective view of a cylinder having a biased bearing mechanism.

FIG. 11 is a front partial cut-away view of the second embodiment gas block.

FIG. 12 is an exploded view of the second embodiment gas block.

FIG. 13 is a cut-away view of the second embodiment adjustable volume gas block with an expanded chamber volume.

FIG. 14 is a cut-away view of the second embodiment adjustable volume gas block with a reduced chamber volume.

FIG. 15 is a cut-away side view of a gas pin of the second embodiment adjustable gas block impinging on the tombstone of an automatic reloading firearm.

FIGS. 16A, 16B, and 16C are cut away side views of chamber screws having different bore sizes.

FIG. 17 is a side view of the second embodiment adjustable volume gas block covered by a hand guard on a firearm.

REFERENCE NUMBERS

• • 10. First Embodiment Gas Block
  • 12. Firearm
  • 14. Anchoring Portion
  • 16. Barrel
  • 18. Chamber Portion
  • 20. Gas Piston
  • 22. Set Screw
  • 24. Gas Passage
  • 26. Bearing Mechanism
  • 28. Bearing
  • 30. Longitudinal Slots
  • 32. Post Screw
  • 34. Screw Head
  • 36. Slot
  • 38. Threaded Portion
  • 40. Slanted Shoulder
  • 42. Post
  • 44. Washers
  • 46. Retainer
  • 48. Piston Head
  • 50. Concave portion
  • 52. Piston Head Slots
  • 54. Chamber Portion Slots
  • 52. Larger Chamber Portion
  • 54. Smaller Chamber Portion
  • 56. Spring
  • 58. Pin
  • 100. Second Embodiment Gas Block
  • 102. Gas Operated Reloading System
  • 104. Gas Pin
  • 106. Tombstone
  • 108. Anchoring Portion
  • 110. Chamber Portion
  • 112. Impinging Screw
  • 114. Chamber Screw
  • 116. Portal
  • 118. Broadened Slot
  • 120. Screw Head
  • 122. Bore
  • 124. Socket
  • 126. Bearing Mechanism
  • 128. Cylinder
  • 130. Open End
  • 132. Retaining Portion
  • 134. Bearing
  • 136. Spring
  • 138. Screw Set
  • 140. Divot
  • 142. Gas Pin Head
  • 144. Channels
  • 146. Concave Face
  • 148. Relief Port
  • 150. Gas Pin Spring
  • 152. Chamber Exhaust
  • 154. Bore
  • 156. Hand Guard

DESCRIPTION

Referring to FIG. 1, an adjustable volume gas block 10 is shown affixed to a gas-operated reloading firearm 12. The gas block 10 comprises an anchoring portion 14 which fits around the barrel 16 of the firearm 12 and is in fluid communication with the interior (not shown) of the barrel 16. A chamber portion 18, which comprises an elongated structure, is formed atop the anchoring portion 14. In a preferred embodiment, the chamber portion 18 extends longitudinally back along the barrel 16 from the anchoring portion 14.

Referring to FIG. 2, the gas block 10 comprises two mechanisms for controlling the gas pressure coming from the barrel 16, allowing users to precisely control the action of the gas piston 20 of the firearm 12 when reloading. The first, a bearing mechanism 26 includes a set screw 22 designed to impinge the gas passage 24 (see FIGS. 4 and 5) between the barrel 16 and the chamber portion 18. The bearing mechanism 26 urges a bearing 28 (see FIG. 6) against longitudinal slots 30 (see FIG. 6) on the set screw 22 to preserve it in a desired position. The second, adjustable volume mechanism includes a post screw 32 anchored in the chamber portion 18 which, with the addition of one or more washers 44 (see FIG. 3), reduces the volume in the chamber portion 18.

Referring to FIG. 3, the post screw 32 includes a screw head 34, which preferably includes a conventional engaging mechanism, such as a slot 36 or similar mechanism for engaging a tool (not shown) such as a screw driver. Although a slotted screw head 34 is shown, any type of engaging mechanism allowing the post screw 32 to be turned is contemplated. The post screw 32 also includes a threaded portion 38 for engaging the chamber portion 18 of the gas block 10 and to hold the post screw 32 in position. Preferably, the post screw 32 engages the chamber portion 18 to the front of the gas block 10, opposite where the gas piston 20 exits the chamber portion 18. The post screw 32 may also include a slanted shoulder 40 for creating a tight seal against the chamber portion 18.

Still referring to FIG. 3, the post screw 32 includes a post 42 extending from the screw head 34, through the chamber portion 18. The post 42 is substantially narrower than the chamber portion 18 and is adapted to receive one or more washers 44 which will fill the chamber portion 18 once inserted on the post 42. Optionally, a retainer 46 may be included to hold the washers 44 in place.

Referring to FIGS. 4 and 5, two cross sectional views of the gas block 10 are shown having two different pressure settings. Referring to FIG. 4, the post screw 32 has been inserted into the chamber portion 18, with the threaded portion 38 and slanted shoulder 40 engaging complimentary areas of the chamber portion 18 to form a substantially air-tight seal. The post 42 extends backward, through the chamber portion 18 to engage the piston head 48 of the gas piston 20.

Still referring to FIGS. 4 and 5, the piston head 48 may include a concave portion 50, which serves to accommodate the post 42 as well as provide additional chamber area in the chamber portion 18. Preferably, the piston head 48 also includes piston head slots 52, which serve to introduce turbulence into gasses travelling around the piston head. Beyond the piston head 48, chamber portion slots 55 allow excess gasses to escape the chamber portion 18 around the gas piston 20. With only the post 42 occupying the chamber portion 18 between the piston head 48 and the screw head 34, a large volume allows more gas to build up in the chamber portion 18 before urging the gas piston 20 to reload the firearm 12.

Referring to FIG. 5, the set screw 22 is inserted into the chamber portion 18 in the same manner as FIG. 4, but with washers 44 installed on the post 42 of the set screw 22. In this manner, the chamber portion 18 has less volume and allows less gas to build up in the chamber portion 18 before urging the gas piston 20 to reload the firearm 12. Notably, the interior of the chamber portion 18 includes a larger chamber 52 and a smaller chamber 54. The larger chamber 52 is sized to accommodate the washers 44, while the smaller chamber 54 is sized to exclude the washers 44, and is connected to the gas passage 24. In this manner, the washers 44 are forced toward the screw head 34 by gas pressure, and are prevented from entering the smaller chamber 54 and occluding the gas passage 24. The chamber portion 18 also includes an exit portal 55 allowing excess gasses to exit the chamber portion 18

FIG. 6 shows an exploded view of the gas block 10. The anchoring portion 14 of the gas block 10 is installed over the barrel 16 of a firearm 12 (not shown), with the chamber portion 18 extending along the barrel 16 to the rear. The bearing mechanism 26 is assembled by inserting the set screw 22 into the gas block 10 and inserting the bearing 28 to engage the longitudinal slots 30. In one embodiment, the bearing may be held in place by a spring 56, which is anchored in position by a pin 58.

Still referring to FIG. 6, the gas piston 20 is inserted into the chamber portion 18, until the piston head 48 is seated in the smaller chamber 54 (see FIGS. 4 and 5). Preferably a spring (not shown) will be inserted on the gas piston 20 and installed behind the piston head 48 to provide recoil in the chamber portion 18. With the piston head installed in the smaller chamber 54, a series of washers 44, and optionally a retainer 56 may be installed on the post 42 of the post screw 32. The post screw 32 is then installed in the chamber portion 18 and tightened in position using the threaded portion 38 and slot 36, such that the slanted shoulder 40 engages a complimentary surface on the chamber portion 18.

In operation, the gas block 10 may be assembled without washers. In this manner, the bearing mechanism is set to a desired position. When the firearm is fired, gasses passing through the gas passage enter the chamber portion 18 filling the smaller chamber portion 54 and larger chamber portion 52. Due to the enlarged chamber portion 18, and including the concave portion 50 of the piston head 48, a delay, caused by gas filing the chamber portion 18 will slow activation of the gas piston 20.

To reduce the delay, the post screw 32 is removed and one or more washers 44 are installed on the post screw 34. The washers take up a portion of or all of the larger chamber portion 52, such that when the firearm is fired, gas more quickly fills the smaller chamber portion 54 and activates movement of the gas piston 20. Various degrees of pressure may be achieved by only partially filling the larger chamber portion 52 with a desired number of washers 44 and by making corresponding adjustments with the bearing mechanism.

Referring to FIGS. 7 through 17, a second embodiment gas block is shown and described. FIG. 7 shows the second embodiment gas block 100 affixed to the barrel 16 of the firearm 12 having a gas-operated reloading system 102. The second embodiment gas block 100 is similar to the first embodiment gas block 10 in that it engages a gas pin 104, which engages the tombstone 106 of the bolt group for reloading the chamber (not shown).

Referring to FIG. 8, a side view of the second embodiment gas block 100 is shown. Like the first embodiment gas block 10, the second embodiment gas block 100 includes an anchoring portion 108 and a chamber portion 110. The second embodiment gas block 100 also includes an impinging screw 112 for impinging the gas passage (not shown) between the barrel 16 and the chamber portion 110. A chamber screw 114 is installed into the chamber portion 110 of the gas block 100. The impinging screw 112 is preferably incorporated below the chamber screw 114.

Referring to FIG. 9, the chamber screw 114 is shown. The chamber screw 114 includes a portal 116 for allowing expelled gas to enter the chamber 110 from the barrel 16 (see FIG. 8). The portal 116 includes a broadened slot 118 on one end. The purpose of the broadened slot 122 is to allow gas to travel from the barrel 16 into the chamber 110 when the chamber screw 114 is in any of its set positions. The chamber screw 114 also includes a screw head 120 with a bore 122 extending through it.

The screw head 120 preferably includes means for turning or adjusting the position of the screw 114. In the illustrated embodiment a hexagonal Allen wrench socket 124 is shown, although other mechanisms such as slotted screw heads are contemplated. The screw head 120 also includes a threaded portion 124 for engaging the chamber portion 110 of the gas block 100.

Referring to FIG. 10, a bearing mechanism 126 is shown. The bearing mechanism 126 comprises a cylinder 128, which is inserted into the bore 122 on the chamber screw 114 (see FIG. 9). The cylinder 128 is preferably hollow with one open end 130. The open end 130 of the cylinder 128 includes a retaining portion 132 that retains a bearing 134 in the cylinder 128. In one embodiment, the retaining portion 132 may present a conical surface.

Referring to FIG. 11, a front view of the second embodiment gas block 100 is shown in partial cut-away view (see FIG. 8, cut-away reference 11). In this view bearing mechanism 126 is shown incorporated into the bore 122 of the screw head 120. Shown in this view, a spring 136 is visible biasing the bearing 134 out of the bearing mechanism 126 and against the retaining portion 116. The bearing mechanism 126 is substantially flush with the screw head 120, allowing a portion of the bearing 134 to extend past the screw head 120.

Still referring to FIG. 11, a screw set 138 is proximal the screw head 120 when the chamber screw 114 is installed in the chamber portion 110. As the biased bearing 134 rotates adjacent the screw set 138, it is pressed back flush with the screw head 120 under force. The screw set 138 includes divots 140 for accommodating the bearing 134. In this manner, with the bearing disposed in a divot 140, it retains the chamber screw 114 in a predetermined position, according to a predetermined chamber portion 110 volume. In the illustrated embodiment, two divots 140 are shown to present a safety. If the bearing 134 is driven under the force of firing from the first divot 140, the second divot 140 will receive it and prevent the chamber screw 114 from rotating further. Preferably, the timing of the threads (not shown) in the chamber portion 110 and the threads 124 on the chamber screw 126 are such that the bearing 134 will be located in a divot 140 when the chamber screw 114 is in a fully closed position abutting the chamber portion 110.

Referring to FIG. 12, an exploded view of the second embodiment gas block 100 is shown. The gas pin 104 extends through the chamber 110, terminating in a gas pin head 142. The gas pin head 142 is substantially the circumference of the chamber portion 110 interior, but does not create an air tight seal. Rather, several channels 144 are located on the gas pin head 142 to generate turbulence in any gas flow traveling past the gas pin head 142 to provide a cushioning effect. The gas pin head 142 also has a concave face 146, which increases the total volume of the chamber portion 110. The chamber 110 also includes a relief port 148, which allows excess gas to escape the chamber portion 110 once the gas pin head 142 reaches a terminal position at the end of the chamber portion 110 opposite the chamber screw 114.

Referring to FIGS. 13 and 14, the second embodiment gas block 100 is shown in a condition prior to firing (FIG. 13) and during firing (FIG. 14). Referring to FIG. 13, prior to firing, the chamber screw 114 has been turned into the chamber portion 110 to a position of desired pressure. In the illustrated embodiment, the impinging screw 112 has been set to allow gases from firing to travel freely into the chamber portion 110. The chamber screw 114 has also been set to a predetermined position using the screw set 140. In the illustrated embodiment, the chamber screw 114 is fully inserted into the chamber portion 110 such that it abuts the gas piston head 142. When the firearm is fired, gasses enter the chamber and exert pressure according to the arrows.

Referring to FIG. 14, after firing, gasses press against the chamber screw 114, which is anchored in place, and the gas pin head 142, forcing the gas pin 104 rearward against the tombstone 106 (FIG. 7). To allow pressure relief, some gas may make its way around the gas pin head 142, encountering the channels before exiting through the chamber exhaust 152. The major portion of the gas produced from firing forces the gas pin head 142 backward, compressing the spring 136, until the gas pin head 142 clears the relief port 148 and exits the chamber 110. Preferably the relief port 148 is positioned on the chamber 110 such that the gas pin head 142 clears the relief port 148 when the gas pin spring 150 is in a fully compressed position. Any remaining gases in the chamber 110 can also travel back into the barrel 16 and exit before the next round is fired.

Referring to FIG. 15, the opposite end of the gas pin 104 is shown where it engages the tombstone 106 on the firearm 12. By pushing back the tombstone, the gas pin 104 causes the bolt group (not shown) to move through its operating cycle. Referring to FIGS. 16A-16C, several sizes of chamber screws 114 are shown with different bore 154 sizes according to user preference. The different bore 154 sizes establish different volumes in the chamber portion 110. While turning the chamber screw 114 in the chamber 110 allows fine tuning of the gas block 100, in certain instances a much larger or smaller volume is desired. In these instances, a chamber screw 114 having an enlarged or reduced bore 154 is contemplated.

Referring to FIG. 17, a hand guard 156 is shown attached to the firearm 12 over the gas block 100 (not shown). Due to the reduced size of the gas block 100 compared to other, larger systems, the gas block 100 need not be removed prior to installation of the hand guard 156. This allows the gas relief characteristics of the gas block 100 to be used even while the hand guard 156 is in place.

While particular forms of the invention have been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except by the full breadth and scope of the appended claims.

Claims

1. An adjustable volume gas piston system for a pneumatic reloading firearm having a barrel with a muzzle, comprising:

a gas block having an anchoring portion for anchoring along the barrel;

a chamber portion in pneumatic connection with the barrel, the chamber portion having a first end proximal the muzzle and a second end distal from the muzzle;

a removable plug having a bore, the plug affixed to the chamber portion at the first end; and

the second end having an opening to receive a gas pin, wherein the gas pin comprises a gas pin head retained in the chamber portion and biased toward the first end, and wherein upon firing the firearm, the volume of the bore causes a pressure delay on the gas pin head, thereby delaying the timing of pneumatic reloading.

2. The gas piston system of claim 1 wherein the plug moves relative to the chamber portion.

3. The gas piston system of claim 1 wherein the plug comprises a threaded member that rotatably engages the chamber portion.

4. The gas piston system of claim 1 wherein adjusting the position of the plug changes the volume inside the chamber portion.

5. The gas piston system of claim 1 wherein the plug comprises a biased stop mechanism that preserves the volume of the chamber portion at a predetermined volume.

6. The gas piston system of claim 5 wherein the biased stop mechanism comprises a bearing in a biased position on the plug and a complimentary seat on the gas block.

7. The gas piston system of claim 6 wherein the gas block comprises multiple seats capable of anchoring the plug in multiple positions.

8. The gas piston system of claim 1 wherein prior to firing the gas pin head is biased to a position abutting the plug.

9. The gas piston system of claim 1 wherein the gas pin head comprises a concave surface facing the bore.

10. The gas piston system of claim 1 wherein the gas pin head comprises circumferential channels that introduce turbulence into gases passing between the gas pin head and the chamber portion.

11. The gas piston system of claim 1 wherein the second end comprises a cut-out that allows gasses passing between the gas pin head and the chamber portion to exit through the second end.

12. The gas piston system of claim 1 wherein the chamber portion comprises an exhaust port obscured by the gas piston head in a biased position.

13. The gas piston system of claim 12 wherein the exhaust port is obscured by the gas pin head prior to firing the firearm and is cleared by the gas pin head when the gas pin head is pushed toward the second end.

14. The gas piston system of claim 1 further comprising an impinging screw between the barrel and the chamber portion for closing the pneumatic connection.

15. An adjustable volume gas block for a firearm having a barrel and a gas pin, comprising:

a plug having a bore;

the plug inserted into the gas block bringing the bore in pneumatic communication with the barrel;

the gas pin biased against the bore forming an enclosed chamber; and

wherein when the firearm is fired, gas enters the enclosed chamber, forcing the gas pin away from the bore; and

wherein as the gas pin moves away from the bore a port is exposed allowing the gas to exit the gas block.

16. The gas block of claim 15 wherein the plug comprises a threaded member for rotatably engaging the chamber portion.

17. The gas block of claim 15 wherein the plug comprises a biased stop mechanism for preserving the volume of the chamber portion at a predetermined volume.

18. The gas block of claim 17 wherein the biased stop mechanism comprises a bearing on the plug and a seat on the gas block.

19. The gas block of claim 18 wherein the gas block comprises multiple seats for anchoring the plug in multiple positions.

20. A method of adjusting the timing of an automatic reloading firearm having a gas pin and a barrel, comprising the steps of:

providing a gas block having a chamber;

installing a gas block on the barrel;

providing a pneumatic communication in the gas block between the chamber and the barrel;

providing a plug having a bore;

inserting the plug into the chamber;

inserting the gas pin into the chamber opposite the plug; and

firing the firearm, thereby causing a delay in the automatic reloading action of the gas pin.