Firearm of the rotating bolt type

A firearm of the rotating bolt type includes a housing part made of plastic or metal, a metal bolt carrier guide, a bolt carrier that is guided by the bolt carrier guide and that has a bolt head rotatably mounted in it, and, held by the housing part, a metal barrel nut in which a barrel can be fixed and in which the bolt head can be locked. The bolt carrier guide is directly connected with the barrel nut so that it is rigid with respect to movement, at least in the longitudinal direction of the firearm.

This invention relates to a firearm of the rotating bolt type comprising a housing part made of plastic or metal, a metal bolt carrier guide, a bolt carrier that is guided by the bolt carrier guide so that it can be moved longitudinally with respect to the housing part and that has a bolt head rotatably mounted in it, and, held by the housing part, a metal barrel nut in which a barrel can be fixed and in which the bolt head can be locked by rotation so that it is aligned with the barrel.

Firearms of the rotating bolt type are common, for example, in the form of army rifles of the AR-10/15 design, which also includes the American assault rifle M16. To keep the weight of such firearms as small as possible, their housing parts are usually made of plastic or light metal, e.g., aluminum. By contrast, parts such as the barrel, the barrel nut, and the bolt carrier with the bolt head, which are subject to strong stresses, are made of steel. Due to the poor antifriction properties of the steel of the bolt carrier against the aluminum or plastic of the housing part, intensive treatment with special lubricants is necessary. This makes the weapon more sensitive to soiling by powder smoke, sand, mud, ice, etc., whose particles adhere to the lubricant film, substantially reducing the lubricant effect. Therefore, frequent and intensive cleaning is prescribed for the M16, to avoid malfunctions. Austrian patent no. 513.144 of the same applicant discloses putting slide rails made of a material different from the housing material on the inner surface of the housing part to guide the bolt carrier in the housing part, allowing the bolt carrier to slide in the housing part with only a little lubricant, or even without any at all.

This invention has the goal of further improving the prior art and creating a firearm with high stability and precision.

The invention achieves this goal with a firearm of the type mentioned at the beginning which is characterized in that the bolt carrier guide is, at least in the longitudinal direction of the firearm, directly connected with the barrel nut so that it is rigid with respect to movement.

Such a direct connection between the bolt carrier guide and the barrel nut ensures reliable function of the rotating bolt over a long service life of the firearm, since the movable bolt carrier is permanently precisely supported with respect to the barrel nut and the barrel. Since the largest forces occur in the longitudinal direction of the firearm, a connection that it is rigid with respect to movement only in this direction is already sufficient to achieve this support effect. The parts that are subject to strong stresses, i.e., the barrel, the barrel nut, the bolt carrier guide, and the bolt carrier with the bolt head, which have a decisive influence on the durability, stability, and precision of the firearm, can be dimensioned and built according to their requirements, while the housing and the housing part are largely free of such stress and thus can be built in an especially weight-saving way. The bolt carrier is securely guided in the bolt carrier guide, so that their material pairing can be matched with respect to good antifriction properties and robustness. The barrel, barrel nut, and rotating bolt can, if desired, also be replaceable, in order, e.g., to replace worn out parts and/or to change the caliber of an existing firearm.

In order to create a simple, stable, and nevertheless detachable connection between the bolt carrier guide and the barrel nut, it is favorable for the bolt carrier guide to be connected with the barrel nut through a tongue-and-groove connection that produces rigidity in the longitudinal direction of the firearm.

According to another advantageous embodiment, the bolt carrier guide is connected with the barrel nut by a screw connection, welding, pressing, or something similar. This produces a connection of the bolt carrier guide with the barrel nut that it is rigid with respect to movement in all directions, which leads to even higher stability of the firearm and is also either permanent or detachable, depending on the embodiment.

It is especially favorable if the bolt carrier guide additionally has a frictional or form-fit connection with the housing part. This ensures secure seating of the bolt carrier guide on the housing part. This also increases the precision of the firearm when combined with, e.g., a sighting device on the housing part. Furthermore, the forces absorbed by the bolt carrier guide can be selectively transferred to the housing part.

According to an especially advantageous embodiment, the bolt carrier guide has an essentially C-shaped cross section, each end of the C forming an inward directed rail, which rails engage into lateral longitudinal grooves of the bolt carrier. A bolt carrier guide shaped in this way is simple to produce and is itself already especially stable, also allowing it to be produced in a way that saves material and thus weight. Furthermore, the inward directed rails cooperating with the longitudinal grooves on the side of the bolt carrier produce a permanently secure and precise sliding seat, thereby preventing tilting of the bolt carrier in the bolt carrier guide and consequently also preventing jamming and/or damage of the firearm.

It is especially favorable if the bolt carrier guide has anchors on which a grip part is directly mounted. In this way, forces, especially those acting in the longitudinal direction of the weapon, are carried away directly to the grip part and to a buttstock that is usually connected with it in such firearms, and onto the shoulder of a rifleman. This takes even more force off the housing part. In this case, the bolt carrier guide represents a central element for connection of all parts of the firearm that are essential for its function.

In another advantageous variant of the firearm, the bolt carrier guide has an opening for connection of a magazine well and for the passage of a firing mechanism. This ensures the usual feed of ammunition and also usual firing; such a bolt carrier guide has a frame-like structure, which saves weight, while having comparable stability.

According toFIG. 1a firearm1has a housing part2and a grip part3. The housing part2holds a barrel nut4, in which a barrel5can be fixed from the front, e.g., by means of a bayonet coupling6. The firearm1is, e.g., a portable firearm, for instance a semiautomatic or automatic rifle.

The firearm1has a rotating bolt7with a bolt carrier8and a bolt head9that is mounted in the bolt carrier8so that the bolt head9is at least rotatable, as a rule also slightly axially movable.

The bolt carrier8is guided in a bolt carrier guide10so that it is, with respect to the housing part2, longitudinally movable, i.e., movable in the direction of the longitudinal axis L (FIG. 2) of the firearm1, between a front end position, in which the bolt head9is locked by rotation in the barrel nut4to align with the barrel5, and a rear end position in which the rotating bolt7is open.

The housing part2serves essentially to protect the mechanically movable elements of the firearm1, e.g., the rotating bolt7, from contact and soiling, for protection from touching the barrel5, which is hot in operation, and to fasten attachments to the firearm1, e.g., on a Picatinny rail11. In contrast to the parts of the firearm1such as the barrel5, the barrel nut4, the rotating bolt7, and the bolt carrier guide10, which are subject to strong mechanical stresses in operation, the housing part2—and moreover also the grip part3—can be made of a light material whose mechanical properties are not as good. In this case, the housing part2is made of aluminum or plastic, and the barrel5, the barrel nut4, the rotating bolt7, and the bolt carrier guide10are made of steel.

The grip part3comprises, in addition to a pistol grip12and a buttstock13, which can optionally be adjustable and/or combined into one element, a trigger14to operate a firing mechanism15and a magazine well16for attachment of a magazine17to feed new ammunition to the cartridge chamber18(FIG. 2) of the barrel5.

The structure and action of the bolt carrier guide10are described below on the basis ofFIG. 2throughFIG. 7.

A repeating process begins after the firearm1is fired with the rotating bolt7, which for clarity is shown only in outline inFIG. 2, first being in its front end position (shown inFIG. 2), in which the bolt head9is locked by rotation in a type of bayonet coupling, with its outward directed lugs19a(FIG. 1) behind the inward directed lugs19b(FIG. 3) of the barrel nut4. Then, the repeating process involves the bolt head9rotating in the bolt carrier8, e.g., in a way known in the art with the help of a sliding block guide in the bolt carrier8, unlocking the bolt head9from the barrel nut4, after which the bolt carrier8and bolt head9together slide into the rear end position, possibly withdrawing a spent cartridge case (not shown) from the cartridge chamber18and ejecting it. The next step of the repeating process involves new ammunition being fed from the magazine17through the magazine well16and pushed into the cartridge chamber18by the rotating bolt7, which is being pressed by spring force back into its front end position, the bolt head9once again being locked by rotation in the barrel nut4, e.g., through a sliding block guide. For automatic repeating, the bolt carrier8has a key8afor application of a gas pressure-operated linkage (not shown inFIG. 2).

The bolt carrier guide10is connected with the barrel nut4directly, i.e., in direct contact with it, rigidly with respect to movement, at least in the longitudinal direction, i.e., in the direction of the longitudinal axis L of the firearm1. To accomplish this in the example shown, the bolt carrier guide10has, running transverse to the longitudinal axis L and facing the barrel nut4, a groove20, into which a tongue21of the barrel nut4engages, producing rigidity with respect to movement in the longitudinal direction of the firearm1. It goes without saying that alternatively the groove20and the tongue could be interchanged; furthermore, another type of connection that is rigid with respect to movement could be selected, e.g., a pin or something similar of one of the two components, barrel nut4and bolt carrier guide10, projecting into a recess on the other component. Alternatively or additionally, the bolt carrier guide10can be permanently or detachably connected with the barrel nut4by a screw connection, welding, pressing, or something similar.

If desired, the bolt carrier guide10can additionally have a frictional or form-fit connection with the housing part2. To accomplish this in the example shown inFIG. 3throughFIG. 6, the bolt carrier guide10has, on the side, projections22, which are inserted into depressions23of the housing part2. Alternatively or additionally, the bolt carrier guide10can be cemented with the housing part2, and/or be connected by means of one or more pins, screws, or rivets24(seeFIG. 1andFIG. 2.

In this example, the cross section of the bolt carrier guide10is essentially shaped like a letter “C” lying on its side. Both ends of the C form inward directed rails25a,25bthat engage in longitudinal grooves26a,26bon the side of the bolt carrier8. Thus, the C-shaped bolt carrier guide10partly wraps around the bottom of the bolt carrier8, whose cross section is essentially approximately circular, except for the key8a, and the bolt carrier8is supported so that it can slide on the rails25a,25bof the bolt carrier guide10, which engage into the longitudinal grooves26a,26bof the bolt carrier8. Alternatively, the longitudinal grooves26a,26band rails25a,25bcould each be arranged on the other part, bolt carrier8or bolt carrier guide10; furthermore, only a single rail, e.g., a T-shaped rail, could engage into a groove that is complementary to it, or the C of the bolt carrier guide10could wrap around the bolt carrier8over more than half of its circumference.

The grip part3could be put on the housing part2and close it off on the bottom; however, in this case the bolt carrier guide10has anchors for this purpose, here front and rear transverse holes27a,27b. The grip part3is put directly on these anchors27a,27b, e.g., with pins28a,28b. Alternatively, the anchors could be screw, rivet, catch, or similar anchors; furthermore, the grip part3could be put on the bolt carrier guide10with the help of only a single anchor.

For connection of the magazine well16and for the passage of the firing mechanism15that is actuated by the trigger14and that uses, e.g., a hammer29to actuate a firing pin mounted in the rotating bolt7, the bolt carrier guide10has an opening30, which in this example extends over wide parts of the bottom of the “C” (seeFIG. 4). Depending on the design of the grip part3, the opening30can be continuous or be subdivided by one or more crossbars of the bolt carrier guide10.

The invention is not limited to the presented embodiments, but rather comprises all variants, combinations, and modifications that fall within the scope of the appended claims.