Firearm with barrel cinching clamp

Firearms with barrel cinching clamps have a receiver having a forward portion defining an internally threaded bore, a barrel having a threaded end removably received in the bore, at least a selected portion of the forward portion being split by a gap, the selected portion having connection elements on opposite sides of the gap, and an adjustable element connected to the connection elements and operable to narrow the gap to secure the barrel in the bore and to widen the gap to permit the barrel to be readily unscrewed from the bore. The bore may define a bore axis, and the gap may be parallel to the bore axis. A circumferentially complete portion of the threaded bore including a plurality of threads adjacent to the gap may be unbroken by a gap. The circumferentially complete portion of the threaded bore may be forward and/or rearward of the selected portion.

FIELD OF THE INVENTION

The present invention relates to firearms, and more particularly to firearms with changeable barrels.

BACKGROUND OF THE INVENTION

Firearms with changeable barrels are desirable because the barrel can be replaced as the barrel becomes damaged or too hot, to change the firearm's caliber, or for more compact storage of the firearm.

Heavy machine guns, particularly those with air cooled barrels, often require barrel changes in the field because the barrel has become too hot for continued use without permanently damaging the barrel. Various quick-change mechanisms using latches or pins have been developed to permit rapid barrel replacement of heavy machine guns.

Although a variety of bolt action and semi-automatic and automatic rifles permit barrel changes, they typically require specialized tools. For example, to change an AR-15 barrel, the upper receiver is held in a vise block to provide a secure and steady hold on the upper receiver, a specialized barrel nut wrench is used to unscrew the barrel nut so the barrel can be removed, and a torque wrench must be attached to the specialized barrel nut wrench in order to tighten the barrel nut once the new barrel is in place. An alternative modular rifle system design eliminates the need for a vise block, but requires attaching a specialized takedown/assembly tool to the receiver and using a gear drive torque wrench to engage gear teeth on a specialized barrel design in order to tighten and loosen the barrel.

The disadvantages of both of these approaches are the need for specialized tools and associated difficulties associated with changing barrels in the field. Not only is there a risk of under torqueing or over torqueing the receiver or barrel nut, resulting in loosening or breakage, but it is also easy to lose the aim of an attached scope. The user may not notice the misalignment of the scope until after taking a shot that misses or strikes an unintended target.

Therefore, a need exists for a new and improved firearm that can be used to change barrels having a standard barrel thread in such a manner that under torqueing or over torqueing are not possible and an attached scope is unlikely to be disturbed. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the firearm with barrel cinching clamp 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 facilitating barrel replacement when the barrel becomes damaged or too hot, to change the firearm's caliber, or for more compact storage of the firearm.

SUMMARY OF THE INVENTION

The present invention provides an improved firearm with barrel cinching clamp, 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 firearm with barrel cinching clamp that has all the advantages of the prior art mentioned above.

To attain this, the preferred embodiment of the present invention essentially comprises a receiver having a forward portion defining an internally threaded bore, a barrel having a threaded end removably received in the bore, at least a selected portion of the forward portion being split by a gap, the selected portion having connection elements on opposite sides of the gap, and an adjustable element connected to the connection elements and operable to narrow the gap to secure the barrel in the bore and to widen the gap to permit the barrel to be readily unscrewed from the bore. The bore may define a bore axis, and the gap may be parallel to the bore axis. A circumferentially complete portion of the threaded bore including a plurality of threads adjacent to the gap may be unbroken by a gap. The circumferentially complete portion of the threaded bore may be forward and/or rearward of the selected portion. 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

A preferred embodiment of the firearm with barrel cinching clamp of the present invention is shown and generally designated by the reference numeral10.

FIG. 1illustrates improved firearm with barrel cinching clamp of the present invention. More particularly, the firearm with barrel cinching clamp10is a rifle. The rifle has a pistol grip22at its rear76, a trigger24, a magazine26, a receiver12, and a barrel16. The barrel has a central bore (the chamber82portion is visible) that defines a bore axis42. The barrel is threadedly connected to the front38of the receiver. A chassis14is connected to the bottom40of the receiver. A scope28is attached to a rail72formed by the top32of the receiver. The right side34of the receiver defines an ejection port30. A bolt carrier20is slidably received within the receiver.

The front38of the receiver defines a threaded bore50. The rear80of the barrel has barrel threads up until the point where a flange84circumferentially protrudes from the barrel. The barrel threads engage the threaded bore to secure the barrel in place. A clearance space76exists between the bore threads86and the flange to facilitate the mating of the barrel threads with the bore threads. A clearance space also exists between the top78of the chassis14and the right boss52and left boss54(only the left boss54is visible) that extend downwards from the bottom40of the receiver so the bosses are free to move. The bosses will be described in more detail subsequently.

FIG. 2illustrates the bottom40of the front38of the receiver12of the present invention. More particularly, the bottom40defines a right boss52and a left boss54. The bosses are essentially cubes when viewed from below. The bosses are separated from one another by a central gap44, and they are also separated from the receiver by side gaps46and48. The right boss has a clearance hole56that is a smooth bore, and the left boss has a threaded bore58. The right side34of the receiver defines a semicircular slot66above the clearance hole56.

FIG. 3illustrates the threaded bore50in the front38of the receiver12of the present invention. More particularly, the threaded bore is circumferentially completely threaded rearward of the clearance space76except for where the central gap44and side gaps46,48are present. The central gap and side gaps to combine to form an H shape, with the central gap being parallel to the bore axis42(shown inFIG. 4) and the side gaps being transverse to the bore axis. The side gaps extend circumferentially about less than one fourth of the circumference of the threaded bore. The right boss52and left boss54also include thread segments where they abut the threaded bore.

FIGS. 4 & 5illustrate the improved firearm with barrel cinching clamp of the present invention. More particularly, the firearm with barrel cinching clamp10is depicted cut sectionally through the chamber82. The cut is viewed from the front inFIG. 4and from the rear inFIG. 5. A hex bolt60is inserted through a circular opening defined by the semicircular slot66in the bottom40of the receiver12and a semicircular slot68in the top70of the chassis14. The semicircular slots are sized to not obstruct rotation and axial movement of the hex bolt head62and to provide access to the hex bolt head. The threaded portion64passes through the clearance hole56in the right boss52, which is sized to permit free passage of the threaded portion and to obstruct the hex bolt head, and threadedly engages the threaded bore58in the left boss54.

Tightening the hex bolt head62creates a clamping action between the hex bolt head62and the threaded portion64engaged with the threaded bore58in the left boss54. The clamping action draws the right boss52and left boss54together, thereby securing the barrel16in position within the threaded bore50in the front38of the receiver12by narrowing the central gap44. A clearance space78between the right and left bosses and the chassis14permits the bosses to be drawn together. A belleville washer88is located below the hex bolt head to give a flexible quality to the bolted joint.

To remove the barrel16from the receiver, the hex bolt60is loosened by rotating the hex bolt head62counterclockwise. With the clamping pressure released, the right boss52and left boss54spring back to their uncinched positions and return the central gap44to its original width. In this position, the right boss and left boss permit the barrel to be readily unscrewed from the threaded bore50in the front38of the receiver12. Subsequently, the barrel can be pulled forward for withdrawal and replaced with a new barrel of the desired caliber. The hex bolt is then replaced and tightened to secure the new barrel in position.

The hex bolt60of the current invention can be tightened and loosened by a conventional Allen wrench rather than a specialized tool. In addition, an appropriately sized Allen wrench may be securely received in the buttstock of the firearm10to make the wrench readily available to the user in the field.

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 in the direction towards the muzzle of the firearm.