Recoil system for a self-loading firearm

A recoil system for a self-loading firearm has a rear mount, a capture element connected to the rear mount with a floor surface and guide rod, a first spring encompassing the guide rod with a rear end abutting the floor surface, a first sleeve defining a bore encompassing the first spring with a forward end abutting a forward end of the first spring, a second spring receiving the first sleeve with a rear end abutting a rear portion of the first sleeve, a second sleeve defining a bore encompassing the second spring with a forward end abutting a forward end of the second spring, a third spring receiving the second sleeve with a rear end abutting a rear portion of the second sleeve, and a bolt carrier having a rear face abutting a forward end of the third spring and an opening receiving a forward end of the second sleeve.

FIELD OF THE INVENTION

The present invention relates to firearms, and more particularly to recoil systems for self-loading rifles.

BACKGROUND OF THE INVENTION

Many self-loading rifles use direct gas impingement as their mechanism of operation. Gas is trapped from the barrel as the bullet moves past a gas port. The gas enters the port and travels down a gas tube into the rifle's upper receiver. Here, the gas tube protrudes into a bolt carrier key, which receives the gas and transfers it into the bolt carrier.

The bolt and bolt carrier together act as a piston, which moves rearward toward the butt of the firearm as the bolt carrier fills with high pressure gas. A buffer that is aligned with a bolt return spring is located behind the bolt carrier. The bolt return spring pushes the bolt carrier back toward the chamber to return the bolt into battery. The length of the rifle buffer tube (typically 10 inches to receive a 6 inch buffer and a 12.75 inch rifle bolt return spring) can compose a significant portion of the overall length of a self-loading AR-15 rifle (typically 35 inches with a 20 inch barrel and a stock).

Compact rifles are desirable for interior defense and other close quarters battle applications where a longer rifle could be difficult to maneuver or easily snagged. Traditional efforts to produce compact rifles result in either short-barreled rifles (rifles with barrels shorter than 16 inches or that fold to under 26 inches), or rifles that omit a shoulder stock to reduce the firearm's length. Short-barreled rifles are subject to strict regulation under the National Firearms Act. Pistols based on rifles such as the AR-15 avoid these regulations, but are large and heavy, and can be difficult to shoot accurately without a shoulder stock or arm brace to provide stability.

Therefore, a need exists for a new and improved recoil system for a self-loading firearm that decreases the overall length of a firearm by replacing the conventional rifle-length buffer. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the recoil system for a self-loading firearm according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of decreasing the overall length of a firearm.

SUMMARY OF THE INVENTION

The present invention provides an improved recoil system for a self-loading firearm, and overcomes the above-mentioned disadvantages and drawbacks of the prior art. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide an improved recoil system for a self-loading firearm that has all the advantages of the prior art mentioned above.

To attain this, the preferred embodiment of the present invention essentially comprises a body defining a bolt passage on a bolt axis, and configured for attachment of a barrel to a forward portion of the body in line with the bolt axis, and having a rear mount facility registered with the bolt axis, a capture element connected to the rear mount facility and having a floor surface facing a forward direction along the bolt axis, a guide rod connected to the capture element and extending along the bolt axis, a first spring closely encompassing the guide rod and having a first spring rear end abutting the floor surface of the capture element, a first sleeve defining a first sleeve bore closely encompassing the first spring and having a first sleeve forward end portion abutting a forward end of the first spring, a second spring closely receiving the first sleeve and having a second spring rear end abutting a rear portion of the first sleeve, a second sleeve defining a second sleeve bore closely encompassing the second spring and having a second sleeve forward end portion abutting a forward end of the second spring, a third spring closely receiving the second sleeve and having a third spring rear end abutting a rear portion of the second sleeve, and a bolt carrier having a rear end with a rear face abutting a forward end of the third spring and defining an opening receiving a forward end of the second sleeve. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached.

DESCRIPTION OF THE CURRENT EMBODIMENT

An embodiment of the recoil system for a self-loading firearm of the present invention is shown and generally designated by the reference numeral10.

FIG. 1illustrates the improved recoil system for a self-loading firearm10of the present invention. More particularly, the recoil system is shown installed in a firearm100, which is a self-loading AR-15 pistol in the current embodiment. The firearm has an upper receiver102, lower receiver104, barrel106, pistol grip108, trigger110, and folding arm brace112. The folding arm brace is depicted in the folded condition. The front114of the folding arm brace has a cavity116that receives the portion of the buffer tube/capture element12of the recoil system that protrudes from the rear118of the upper receiver. A folding shoulder stock is also compatible with the recoil system and firearm, but would make the firearm a short-barreled firearm subject to the National Firearm Act because it would have a folded length of less than 26 inch. The use of the folding arm brace makes the firearm an AR-15 pistol, which provides some of the advantages of a short-barreled rifle without being subject to the National Firearms Act. Although an auto-loading AR-15 pistol is disclosed and illustrated, the firearm can also be an AR-15 rifle if a stock is used, or an M4 or M16 pistol or rifle if an arm brace or stock are used. It should be appreciated that the recoil system of the current invention results in the shortest-ever M4, M16, or AR-15 platform that uses military-specification upper and lower receivers because the buffer tube12only protrudes 1.750 inch from the rear of the upper receiver. In contrast, a conventional rifle length buffer tube protrudes 9.5 inch beyond the lower receiver, and a carbine length buffer tube protrudes from 6.750 inch to 7.750 inch beyond the lower receiver depending upon the manufacturer. The decreased length compared to a conventional AR-15 pistol makes the firearm of the current invention easier to shoot accurately. Furthermore, the firearm with the recoil system of the current invention installed is capable of normal operation even with the folding arm brace or stock in the folded condition, or completely removed. The folding arm brace or stock factory release button has been replaced with a two-piece spring-tensioned button that allows for both the folding of a stock or brace and rapid removal by depressing the button to a second stage that releases the stock or brace completely from the groove “G” inFIG. 5. Groove “G” inFIG. 5also allows for the folding stock or brace to be quickly attached by pushing it forward until the spring tension locks it into groove “G”.

The upper receiver102in combination with a bolt carrier32is a body that defines a bolt passage126on a bolt axis120. The upper receiver is configured for attachment of the barrel106to a forward portion122of the upper receiver in line with the bolt axis. The upper receiver has a threaded rear mount facility124registered with the bolt axis.

FIGS. 2 & 3illustrate the improved recoil system for a self-loading firearm10of the present invention. More particularly,FIG. 3shows the recoil system in the battery position. The recoil system has a buffer tube/capture element12that is an external cap that threadedly connects to the rear mount facility128on the upper receiver102using external threads94. The buffer tube has a floor surface14facing a forward direction along the bolt axis120. A guide rod16has a rear18forming a hex head (not visible) secured to the floor surface by threads (not shown) threadedly engaged with threaded aperture20in the floor surface. The front22of the guide rod extends along the bolt axis and defines a central bore24that receives the rear26of a bolt carrier stop28. The bolt carrier stop provides a tapered rubber tip30to the guide rod in the current embodiment. The guide rod and tapered rubber tip stop further rearward movement of the bolt carrier32when the recoil system reaches the full recoil compressed condition illustrated inFIG. 4to prevent coil bind of the first, second, and third springs58,70,84. Coil bind is highly undesirable because a spring experiencing coil bind has been found to be permanently deformed in as little as twenty discharge cycles.

The bolt carrier32has a right side34, left side36, front face38, rear end portion40, top42, and bottom44. The front face and rear end portion define a central bore46axially registered with the bolt axis120. The top front of the frame defines a charging handle engagement shelf48. A cam slot50is defined by the top of the frame immediately behind the charging handle engagement shelf. A gas key attachment area52is machined in the top of the frame directly behind the cam slot. A gas key54is attached to the gas key attachment area. A hammer clearance slot56, which communicates with the central bore46is machined in the top of the frame immediately behind the carrier key attachment area.

The first spring58closely encompasses the guide rod16and has a first spring rear end60abutting the floor surface14of the buffer tube/capture element12. A first sleeve62defining a first sleeve bore64closely encompasses the first spring and has a first sleeve forward end portion66abutting a forward end68of the first spring. The second spring70closely receives the first sleeve and has a second spring rear end72abutting a rear external flange portion74of the first sleeve. A second sleeve76defining a second sleeve bore78closely encompasses the second spring and has a second sleeve forward end portion80abutting a forward end82of the second spring. The third spring84closely receives the second sleeve and has a third spring rear end86abutting a rear external flange portion88of the second sleeve. The second sleeve includes a rear internal diagonal chamfer130. The rear end portion40of the bolt carrier32has a rear face92abutting a forward end90of the third spring. The central bore46in the bolt carrier is an opening receiving the second sleeve forward end portion.

In the current embodiment, the first, second, and third springs58,70,84are compression coil springs made of steel. The buffer tube12, first sleeve62, and second sleeve76are preferably made of tool steel to provide sufficient durability to withstand repeated exposure to recoil forces. It is believed plastic components would not last, and aluminum components would be too soft. The first sleeve forward end portion66defines a limited first aperture96configured to closely receive the guide rod and having a diameter smaller than an outside diameter of the first spring. The rear external flange portion74of the first sleeve is a first external flange having a greater diameter than the interior diameter of the second spring. The second sleeve forward end portion80defines a limited forward second aperture98configured to closely receive the first sleeve, and a diameter smaller than an outside diameter of the second spring. The rear external flange portion88of the second sleeve is a second external flange having a greater diameter than the interior diameter of the third spring. The first sleeve is axially movable with respect to the buffer tube/capture element12and with respect to the bolt carrier32. The first sleeve is suspended between the buffer/tube capture element and the bolt carrier with axial support only by the first and second springs.

FIG. 4illustrates the improved recoil system for a self-loading firearm10of the present invention. More particularly,FIG. 4shows the recoil system in the recoil position. By comparingFIGS. 3 & 4, it is readily apparent that the bolt carrier32is movable between a recoil position (FIG. 4) and a battery position (FIG. 3). The first sleeve forward end portion66is forward of the second sleeve forward end portion80when the bolt carrier is in the recoil position. The majority of the first sleeve62is forward of the forward end/front22of the guide rod16when the bolt carrier is in the battery position. The majority of the second sleeve76is forward of the first sleeve forward end portion when the bolt carrier is in the battery position. The rear end portion40of the bolt carrier is forward of a majority of the second sleeve when the bolt carrier is in the battery position. The forward end82of the second spring70is rearward of the forward end68of the first spring58when the bolt carrier is in the recoil position. The second spring rear end72is forward of the first spring rear end60when the bolt carrier is in the recoil position. The forward end of the third spring84is rearward of the forward end82of the second spring when the bolt carrier is in the recoil position. The third spring rear end86is forward of the second spring rear end when the bolt carrier is in the recoil position.

It should also be appreciated that the first sleeve62receives the first spring58, the second spring70receives the first sleeve, the second sleeve76receives the second spring, and the third spring84receives the second sleeve. The first sleeve forward end portion66operably engages the forward end68of the first spring, and the rear external flange portion74of the first sleeve operably engages a second spring rear end72. The second sleeve forward end portion80operably engages the forward end82of the second spring, and the rear external flange portion88of the second sleeve operably engages the third spring rear end86. The forward end portions of the first and second sleeves serve as internal forward stops.

FIG. 5illustrates the buffer tube/capture element12. In the current embodiment, the buffer tube/capture element has an outer diameter A of 1.307+/−0.005 inch, an outer diameter B of 1.1875+/−0.005 inch, an external threaded area C that is 0.420 inch wide with external threads94that are 1 3/16×16 threads per inch, an external area D that is 0.580 inch wide, an external groove E that is 0.0875 inch wide and 0.090 inch deep, an external area F that is 0.300 inch wide, an external groove G that is 0.195 inch wide and 0.090 inch deep, the threaded aperture20with a width denoted by H of 0.255 inch, an inner diameter I of 0.937 inch, 45° angles J and K, an outer diameter L of 1.150 inch, and a fixture hole M with a diameter of 0.195 inch and a depth of 0.085 inch. The buffer tube/capture element has a maximum interior depth of 2.050 inch.

FIG. 6illustrates the first sleeve62. In the current embodiment, the first sleeve has an outer diameter N of 0.630 inch, an inner diameter O of 0.453 inch, an external area P that is 0.092 inch wide, an external area Q that is 1.730 inch wide, an external area R that is 1.820 inch wide, 45° angles S, an inner diameter T of 0.332 inch, and 45° angles U.

FIG. 7illustrates the second sleeve76. In the current embodiment, the second sleeve has an outer diameter V of 0.880 inch, 45° angles W, an inner diameter X of 0.656 inch, an external area Y that is 0.060 inch wide, an external area Z that is 1.310 inch wide, an external area AA that is 1.375 inch wide, an external area BB that is 0.150 inch wide, 45° angles CC, an inner diameter DD of 0.531 inch, and an outer diameter EE of 0.730 inch.

In the current embodiment, the bolt carrier32has 45° angle stops FF, and the second sleeve76has a 45° mating angle CC that stops the second sleeve to prevent coil bind of the third spring84. The bolt carrier has ledge depth GG of 0.760 inch. The bolt carrier has an overall length of 4.400 inch for .223/5.56, 7.62×39, and 300 AAC Blackout cartridges. The guide rod16has an outer diameter of 0.320 inch and a length of 1.740 inch. The exposed portion of the bolt carrier stop28provides an additional length of 0.360 inch. In the full recoil condition shown inFIG. 4, the nested springs and sleeves compress to a point that they only add an additional length of 0.550 inch to the total length of the bolt carrier. This makes the overall length of the bolt carrier and recoil system when compressed during recoil and extraction less than 5.000 inch. However, the bolt carrier is still capable of the full amount of longitudinal movement associated with an AR-15 or M-16 having a conventional length buffer tube. The resiliency characteristics of the second spring70can be modified to accommodate the recoil characteristics associated with the caliber of the cartridge being used. For example, a lighter second spring can be used with a suppressed300Blackout cartridge with a light round, and a heavier second spring can be used with a 7.62×39 cartridge.

In the context of the specification, the terms “rear” and “rearward,” and “front” and “forward” have the following definitions: “rear” or “rearward” means in the direction away from the muzzle of the firearm while “front” or “forward” means it is in the direction towards the muzzle of the firearm. Furthermore, the term “battery position” means the firearm is loaded and the bolt is locked, making the firearm ready to fire. The term “recoil position” means the firearm has discharged and is the point where the bolt carrier has reached its maximum point of rearward movement.

While a current embodiment of a recoil system for a self-loading firearm has been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. For example, although a gas impingement mechanism of operation has been disclosed, piston or blowback-operated mechanisms of operation could also be used.