CROSS-REFERENCE TO RELATED APPLICATIONS
FIELD OF THE INVENTION
This application claims priority to U.S. Provisional Application Ser. No. 60/540,360, filed Jan. 30, 2004, which is incorporated by reference herein in its entirety.
- BACKGROUND OF THE INVENTION
The present invention relates generally to firearms, and in particular, to the assembly of a barrel and receiver and a method to set and maintain the head space of a bolt and barrel breach interface.
- SUMMARY OF THE INVENTION
Manufacturers of firearms constantly seek improvements in the way firearms are manufactured. Specifically, manufacturers seek enhanced manufacturability and process control to optimize quality and production quality. At the same time, the end-user seeks customization and ease of repair and replacement of parts of the firearm. Thus, there is a need for a firearm design that enhances manufacturability and process control, while simplifying customization and repair.
The present invention generally is directed to a receiver and barrel assembly for a firearm, such as a rifle or other long gun or other types of firearms, and a method for assembling and attaching the barrel and receiver and setting the head space between the bolt and the barrel. According to the present invention, the firearm readily is assembled at the time of manufacture, and readily disassembled as needed or desired to meet the needs of the individual shooter, without the need for special tooling or equipment.
According to one aspect of the present invention, a split receiver for use in the barrel assembly of the present invention comprises a substantially cylindrical body having an aft end and a fore end. The body of the receiver has an axial bore extending therethrough from the aft end to the fore end, and a slot extending from the fore end toward the aft end of the body.
The receiver also comprises a set screw or clamping screw aligned radially with the slot. The clamping screw may be positioned to tighten in a direction substantially perpendicular to the slot. The receiver also may include a barrel set screw proximate the fore end of the receiver. The barrel set screw may be positioned to tighten in a direction substantially perpendicular to the axial bore of the receiver. The barrel set screw may have a cone point that marks the barrel upon tightening.
A barrel comprising a mating portion dimensioned to be received in the axial bore engages the open fore end of the receiver. In this position, the receiver can engage and secure the barrel into the receiver by tightening the clamping screw and the barrel set screw at a desired head space. Upon tightening the clamping screw and barrel set screw, a taper is formed in the receiver at the fore end, thereby securing the barrel and the receiver.
According to another aspect of the present invention, a method of assembling a receiver and barrel is provided. The method includes providing a receiver having an axial bore therethrough and a slot having an open width, inserting a mating portion of a barrel into the axial bore, and tightening a securing means substantially radially aligned with the slot. The mating portion of the barrel is inserted into the axial bore to an extent needed to achieve a desired head space. Tightening the securing means then decreases the open width of the slot and deforms the receiver toward and against the barrel.
BRIEF DESCRIPTION OF THE DRAWINGS
Various features, objects, and advantages of the present invention are discussed in, or are apparent from, the detailed description and accompanying drawings set forth below.
FIG. 1 is a partially exploded side plan view of an exemplary firearm that may include a receiver and barrel assembly according to the present invention.
FIG. 2 is an exploded perspective view of an exemplary receiver and barrel assembly according to the present invention.
FIG. 3 is an alternate exploded perspective view of an exemplary receiver and barrel assembly according to the present invention.
FIG. 4 is a bottom plan view of an exemplary assembled receiver and barrel according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 is a side plan view of an exemplary assembled receiver and barrel according to the present invention.
In contrast to presently available barrel assemblies, the present invention includes features that improve manufacturability and customization of a firearm. In particular, the features simplify manufacturing and permit rapid barrel replacement and head space adjustment without the need for special tooling or equipment. The present invention as described herein typically is used for rimfire rifle barrel attachment systems, but may be used with other long guns or other types of firearms.
As shown in FIGS. 1-3, the barrel assembly 10 of the present invention generally includes a receiver 15 and a barrel 20 used in connection with a firearm, for example, a rifle F, shown in exploded view in FIG. 1. The receiver 15 has a substantially cylindrical body 22 having a first or aft end 25, a second or fore end 30, and an axial bore 35 extending therethrough from the aft end 25 to the fore end 30. The receiver 15 also includes a slot 40 having an open width W extending a length L from the fore end 30 toward the aft end 25 of the body 22. The open width W and length L vary for a given receiver design. In one aspect, the open width W is from about 0.025 in. to about 0.060 in., for example 0.040 in. In another aspect, the slot 40 has a length from about 0.5 in. to about 1.5 in. for example, 1 inch.
The receiver also includes a clamping screw 38, set screw, locking pin, or other securing means proximate the fore end 30 of the receiver 15 for releasably securing the barrel 20 within the receiver 15. The clamping screw 38 is substantially aligned radially with the slot 40 and tightens in a direction substantially perpendicular to the axial bore 35. In one aspect, the clamping screw 38 is aligned in a substantially perpendicular relation to the slot 40.
The receiver further includes a barrel set screw 48, typically tightened at the time of manufacture. The barrel set screw 48 is positioned so that it tightens in a radial direction, substantially perpendicular to the axial bore 35. In one aspect, the barrel set screw 48 is a cone point screw, so that upon tightening against the barrel 20, the mating portion 55 of the barrel 20 is marked or scored permanently. The marking then can be used to determine whether the barrel 20 has been tampered with after assembly. According to one aspect of the present invention, the slot 40 is extended to a magazine chamber 70, thereby providing an overall clamping length L′ (FIG. 4) of from about 2 inches to about 4 inches, for example, about 3 inches. By doing so, the body 22 of the receiver 15 more readily deforms during assembly, thereby requiring less torque to tighten the barrel set screw 48.
The receiver 15 also may include a guide pin 45 (best seen in FIG. 4) that extends inward from the exterior of the receiver 15 into the axial bore 35. The guide pin 45 may be mounted flush to the exterior of the receiver 15 and may extend into the bore 35 about 0.05 in. to about 0.10 in., although greater or lesser amounts of extension of the guide pin also can be used as needed or desired.
Still viewing FIGS. 1-3, the barrel 20 includes a first end 75 defining a mating portion 55 with a mating shoulder 60 formed thereabout, and a second, distal end 80. The mating portion 55 is dimensioned to be slidably received in the axial bore 35 of the receiver 15. The barrel 20 also may include a guide groove (not shown) or similar directional feature dimensioned to slidably receive the guide pin 45 of the receiver 15. It should be noted that different barrels having different length mating portions also can be provided or used.
To assemble the receiver 15 and barrel 20, the mating portion 55 of the barrel 20 is rotated as needed to align the guide groove 65 and the guide pin 45 of the receiver 15. The mating portion 55 then is slidably inserted into the axial bore 35 of the receiver 15. A bolt assembly 85 is inserted into the receiver 15 and closed. The bolt assembly 85 includes a bolt face 90 having a counterbore (not shown) therein.
According to the present invention, the barrel 20 is slidably adjusted within the axial bore 35 of the receiver 15 along the length thereof until a desired head space is attained. The minimum possible head space is attained by bringing the barrel breach face 105 into contact with the counterbore of the bolt face 90 within the receiver 15. Hard gauging techniques known to those of skill in the art can be used to attain a greater head space if desired.
The ability to adjust the head space in this manner provides significant advantages over presently available receiver and barrel assemblies. Notably, the receiver and assembly of the present invention readily accommodate normal tolerance variations in the barrel and receiver, thereby simplifying the manufacturing process. Additionally, secondary machining typically required to provide a proper engagement of the receiver and barrel is not required.
Turning to FIGS. 4 and 5, when the barrel 20 is positioned relative to the receiver 15 at the desired head space, the clamping screw 38 is tightened. The tightening action causes the open width W of the slot to decrease. Further, the tightening action causes the fore end 30 of the receiver 15 to deform toward and against the mating portion 55 of the barrel 20, thereby forming a taper in the receiver 15. The taper in the receiver decreases the diameter of the receiver 15 at the fore end 30 relative to the original diameter. Depending on the particular firearm, a required torque may be specified. In one aspect, the required torque on the clamping screw is from about 100 in-lbf to about 125 in-lbf. The resulting taper helps to substantially securely clamp the receiver 15 to the barrel 20 seated therein. Additionally, tightening of the clamping screw 38 maintains the desired head space dimension.
Assembly of the barrel 20 and receiver 15 of the firearm F is completed by tightening the barrel set screw 110, which further helps to secure the barrel 20 in the receiver 15. In one aspect, the barrel set screw 110 requires a minimum torque setting of at least about 25 in-lbf. Tightening the barrel set screw 110 in this manner may provide from about 500 lb to about 1000 lb of additional force in securing the barrel 20 in the receiver 15.
In contrast to presently known, more complicated assemblies, only two screws or other securing means are needed to secure the receiver to the barrel. Thus, the simple, easy to use design of the present invention permits the assembly to be customized according to the preferences of the user. Additionally, the present invention allows a damaged or worn barrel and/or receiver to be replaced with little effort or cost.
Accordingly, it will be readily understood by those persons skilled in the art that, in view of the above detailed description of the invention, the present invention is susceptible of broad utility and application. Many adaptations of the present invention other than those herein described, as well as many variations, modifications, and equivalent arrangements will be apparent from or reasonably suggested by the present invention and the above detailed description thereof, without departing from the substance or scope of the present invention.
While the present invention is described herein in detail in relation to specific aspects, it is to be understood that this detailed description is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the present invention. The detailed description set forth herein is not intended nor is to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications, and equivalent arrangements of the present invention, the present invention being limited solely by the claims appended hereto and the equivalents thereof.