FIELD OF THE INVENTION
The present invention relates in general to firearms and, more particularly, to a firearm and method of assembly with two-stage independent taper-lock barrel nuts.
BACKGROUND
Modern firearms are designed and manufactured to operate with multiple inter-operational components and often with modular construction. In one example, an AR-10 or AR-15 style sporting rifle 100 uses a modular construction with an upper receiver 102 and lower receiver 104, as shown in FIG. la. Lower receiver 104 is characterized by trigger guard 106, trigger assembly 108, pistol grip 110, and magazine well 112. Buttstock 114 attaches to lower receiver 104.
Upper receiver 102 is characterized by bolt carrier assembly, forward assist, charging handle, and gas-operated reloader. Ejector 118 provides for exit of spent cartridges from upper receiver 102. Barrel assembly 120 with handguard 122 attaches to upper receiver 102. Lower receiver 104 is attached to upper receiver 102 by removable rear take-down pin 124 and forward pivot pin 126. Removing rear take-down pin 124 allows upper receiver 102 to hinge and rotate about forward pivot pin 126, see FIG. 1b.
Barrel assembly 120 is typically secured to upper receiver 102 with a single barrel nut. The barrel nut torques the barrel to upper receiver 102. Unfortunately, the single barrel nut does not ensure, and generally does not provide, properly alignment between the bore of the barrel and the bore of upper receiver 102. Any misalignment between the bore of the barrel and the bore of upper receiver 102 can cause wear on the bolt, catastrophic failure of the bolt, and un-torqueing of the barrel extension due to vibration and heat expansion. Moreover, even when the barrel is properly secured to the upper receiver via the barrel nut and barrel extension, the ignition of ammunition inside the barrel chamber still can cause the length of the barrel to move, i.e., “whip,” due to harmonic vibration. The harmonic vibration decreases the reliability and accuracy of the barrel.
BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1a-1b illustrate a sporting rifle with conventional upper receiver and lower receiver;
FIGS. 2a-2b illustrate a sporting rifle with an upper receiver, lower receiver, and double barrel nut assembly;
FIGS. 3a-3b illustrate the barrel assembly and barrel in isolation;
FIGS. 4a-4g illustrate a barrel extension mated to the barrel;
FIGS. 5a-5e illustrate various views of the primary barrel nut;
FIGS. 6a-6d illustrate various views of the secondary barrel nut;
FIGS. 7a-7f illustrate assembly of the barrel to upper receiver using the primary barrel nut and secondary barrel nut;
and
FIGS. 8a-8d illustrate the barrel mated to upper receiver with the primary barrel nut and secondary barrel nut.
DETAILED DESCRIPTION OF THE DRAWINGS
The following describes one or more embodiments with reference to the figures, in which like numerals represent the same or similar elements. While the figures are described in terms of the best mode for achieving certain objectives, the description is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure.
FIG. 2a shows an AR-10 or AR-15 style sporting rifle 200 designed for modular construction and manufactured for interchangeability of components. Sporting rifle 200 has upper receiver 202, typically forged or casted then computer numerical control (CNC) machined, and lower receiver 204, typically forged or casted then CNC machined. Lower receiver 204 includes trigger guard 206, trigger assembly 208, pistol grip 210, and magazine well 212. Buttstock 214 attaches to lower receiver 204.
Upper receiver 202 includes bolt carrier assembly, forward assist, charging handle, and gas-operated reloader. Ejector 218 provides for exit of spent cartridges from upper receiver 202. Barrel assembly 220 with handguard 222 attaches to upper receiver 202. Lower receiver 204 is attached to upper receiver 202 by removable rear take-down pin 224 and forward pivot pin 226. Removing rear take-down pin 224 allows upper receiver 202 to hinge and rotate about forward pivot pin 226, see FIG. 2b. Removing forward take-down pin 226 from opening 228 allows upper receiver 202 to disconnect from lower receiver 204.
FIG. 3a shows upper receiver 202 and barrel assembly 220 in isolation, having been detached from lower receiver 204 by releasing rear take-down pin 224 and removing forward pivot pin 226 from opening 228. Elements having a similar function are assigned the same reference number in the figures. FIG. 3b shows inner-most barrel 230 stripped down from barrel assembly 220. Gas port 240 extends through barrel 230 to rifle bore 242. The location of the gas journal is modified for barrel reliability and performance optimization. Barrel 230 also includes beveled or tapered shoulder 268 extending between larger diameter surface 266 and smaller diameter surface 270. Expansion joints 272 cut or otherwise formed into smaller diameter surface 270.
FIG. 4a shows barrel extension 248 with flat shoulder 250. FIG. 4b shows barrel extension 248 and flat shoulder 250 with internal female threading 252. In an alternate embodiment, FIG. 4c shows barrel extension 254 with beveled or tapered shoulder 256. FIG. 4d shows barrel extension 254 with beveled or tapered shoulder 256 and internal female threading 258. In one embodiment, beveled or taper shoulder portion 256 is formed with an angle of 10-60 degrees.
In FIG. 4e, barrel extension 248, leading with shoulder 250, is disposed adjacent to thread-end 260 of barrel 230, proximate to larger diameter surface 266. Threads 252 inside barrel extension 248 are screwed onto threaded-end 260. FIG. 4f shows barrel extension 248 threaded onto threaded-end 260 of barrel 230 and designated as barrel assembly 276. Alternatively, barrel extension 254 with beveled or tapered shoulder 256 and female threading 258 can be threaded onto threaded-end 260 of barrel 230 proximate to larger diameter surface 266, similar to FIG. 4e. FIG. 4g shows barrel extension 254 threaded onto threaded-end 260 of barrel 230 and designated as barrel assembly 278.
FIGS. 4f-4g further show beveled or tapered shoulder 268 extending between larger diameter surface 266 and smaller diameter surface 270. Expansion joints 272 cut or otherwise formed into smaller diameter surface 270. The ignition of ammunition inside the barrel chamber causes an extreme amount of heat and results in the increase in temperature of the barrel material. Barrel material, typically steel or stainless steel, expands in response to the heat. Material heat expansion follows the path of least resistance. In the case of barrels, this path is the rifling machined inside the barrel bore. The rifling will tend to cause the barrel to expand laterally in the presence of heat. Expansion joints 272 on the outside of barrel 230 disrupt the lateral barrel material warping caused by heat expansion. More specifically, expansion joints 272 cause expansion to occur linearly instead of laterally. Linear expansion is preferred as lateral expansion will decrease the accuracy of barrel 230. Accordingly, expansion joints 272 cause barrel 230 to expand and contract in the linear direction shown by arrow 274 in FIG. 3b upon heating while firing and then cooling. Expansion joints 272 prevent or reduce lateral movement of barrel 230.
Barrel assembly 276, 278 is mounted to upper receiver 202 using a two-stage or double independent taper-lock barrel nut assembly, as will be described in FIGS. 7a-7f. The two-stage or double independent taper-lock barrel nut assembly includes a first or primary barrel nut and a second or secondary barrel nut. FIG. 5a shows primary barrel nut 280 with a first primary barrel nut end 282 and second distal primary barrel nut end 284. Primary barrel nut 280 includes a plurality of openings 286 around a perimeter of the shaft and centrally located between primary barrel nut ends 282 and 284. Openings 286 provide leverage points to torque primary barrel nut 280. For example, primary barrel nut 280 can be tightened by inserting a tool, e.g., spanner wrench, into openings 286 to turn the primary barrel nut. Channels 288 can be formed in the shaft for ease of handling and assembly. Primary barrel nut 280 can be made from aluminum, steel, or titanium.
FIG. 5b shows internal arrangement of primary barrel nut 280, from primary barrel nut end 282, with female internal threading 296 and internal flat shoulder 290, which will later contact external flat shoulder 250 of barrel extension 248 upon further assembly. Threading 296 will mate with threading 320 on upper receiver 202. FIG. 5c illustrates a perspective view of the internal arrangement of primary barrel nut 280, from primary barrel nut end 282, with internal flat shoulder 290, which will later contact external shoulder 250 of barrel extension 248 upon further assembly.
FIG. 5d shows a perspective view of primary barrel nut 280 from primary barrel nut end 284 with internal female threading 298 to mate with threading 312 on secondary barrel nut 300. In one embodiment, threading 296 and threading 298 are machined identical to the same size and tolerance.
In accordance with the embodiment of FIGS. 4c-4d, FIG. 5e shows a perspective view of primary barrel nut 280 from primary barrel nut end 282 with internal female threading 296 and beveled or tapered shoulder 292, which will later contact external shoulder portion 256 of barrel extension 254 upon further assembly. Threading 296 will mate with threading 320 on upper receiver 202. Primary barrel nut end 284 has internal female threading 298, similar to FIG. 5d, to mate with threading 312 on secondary barrel nut 300.
FIG. 6a shows secondary barrel nut 300 with a first secondary barrel nut end 302 and second distal secondary barrel nut end 304. Secondary barrel nut 280 includes a smaller diameter surface 306, first beveled or tapered surface 308, larger diameter surface 310, second beveled or tapered surface 311, external male threaded-end 312, and a plurality of openings 314 around a perimeter of the larger diameter surface. Openings 314 provide leverage points to torque secondary barrel nut 300. For example, secondary barrel nut 300 can be tightened by inserting a tool, e.g., spanner wrench, into openings 314 to turn the secondary barrel nut. Secondary barrel nut 300 can be made from aluminum, steel, or titanium.
FIG. 6b shows internal arrangement of second barrel nut 300, from secondary barrel nut end 302, with internal beveled or tapered surface 316, which will later contact beveled or tapered shoulder 268 upon further assembly.
FIG. 6c shows a perspective view of second barrel nut 300 from secondary barrel nut end 302 with external male threaded-end 312. Threaded-end 312 will mate with internal female threading 298 of primary barrel nut 280. FIG. 6d shows a perspective view of second barrel nut 300 from secondary barrel nut end 304.
In FIG. 7a, barrel assembly 276 and primary barrel nut 280 are disposed for assembly with upper receiver or barrel receiving unit 202. The barrel extension 248 side of barrel assembly 276 is oriented toward upper receiver 202, and primary barrel nut 280 is positioned to slide over barrel 230. In FIG. 7b, barrel extension 248 slides into an opening in upper receiver 202 with shoulder 250 remaining outside the upper receiver. Primary barrel nut 280 slides over barrel 230, leading with primary barrel nut end 282. In FIG. 7c, primary barrel nut 280 mates with upper receiver 202 by internal female threading 296 screwing onto threading 320 of the upper receiver. In particular, primary barrel nut 280 is tightened by inserting a tool, e.g., spanner wrench, into openings 286 to turn the primary barrel nut. Primary barrel nut 280 rotates until internal shoulder 290 of the primary barrel nut is brought into contact with external shoulder 250 of barrel extension 248. Primary barrel nut 280 initially secures barrel assembly 276 to upper receiver 202.
In FIG. 7d, secondary barrel nut 300 is disposed for assembly with primary barrel nut 280. External male threading 312 is oriented toward upper receiver 202 and positioned to slide over barrel 230. In FIG. 7e, secondary barrel nut 300 slides over barrel 230, leading with secondary barrel nut end 302. In FIG. 7f, secondary barrel nut 300 mates with primary barrel nut 280 by external male threading 312 screwing onto internal female threading 298 of the primary barrel nut. In particular, secondary barrel nut 300 is tightened by inserting a tool, e.g., spanner wrench, into openings 314 to turn the secondary barrel nut. Secondary barrel nut 300 rotates until internal beveled or tapered shoulder 316 of the secondary barrel nut is brought into contact with beveled or tapered shoulder 268 of barrel 230.
By nature of internal beveled or tapered shoulder 316 contacting beveled or tapered shoulder 268, barrel 230, and correspondingly bore 242, is centered and aligned with upper receiver 202. Secondary barrel nut 300 is tightened to 54-108 newton meters (nm). Once the barrel alignment is secure, primary barrel nut 280 is tightened to 54-108 nm to lock barrel assembly 276 to upper receiver 202. The proper alignment between upper receiver 202 and bore 242 of barrel 230 avoids wear on the bolt, catastrophic failure of the bolt, and un-torquing of the barrel extension due to vibration and heat expansion. The proper alignment between upper receiver 202 and bore 242 of barrel 230 reduces harmonic vibration, while increase dynamics, durability, and accuracy of sporting rifle 200.
Barrel assembly 278 can also be mated to upper receiver using the double barrel nut 280 and 300 assembly process, similar to FIGS. 7a-7f. In particular, primary barrel nut 280 rotates until internal beveled or tapered shoulder 292 of the primary barrel nut is brought into contact with external beveled or tapered shoulder 256 of barrel extension 254. Secondary barrel nut 300 rotates until internal beveled or tapered shoulder 316 of the secondary barrel nut is brought into contact with beveled or tapered shoulder 268 of barrel 230.
FIG. 8a shows further detail of primary barrel nut 280 and secondary barrel nut 300. FIG. 8b is an internal view of primary barrel nut 280 and secondary barrel nut 300 with barrel extension 248 and shoulder 250. The flat surface of shoulder 250 contacts the flat surface of shoulder 290. In particular, shoulder 250 is under torqued contact with internal shoulder 290 of primary barrel nut 280. Beveled or tapered shoulder 268 of barrel 230 is under torqued contact with internal beveled or tapered shoulder 316 in secondary barrel nut 300. In one embodiment, beveled or taper shoulder 268 and 316 are formed with an angle of 10-60 degrees.
FIG. 8c is an internal view of primary barrel nut 280 and secondary barrel nut 300 with barrel extension 254 and beveled or tapered shoulder 256. In particular, beveled or tapered shoulder 256 is under torqued contact with internal shoulder 292 of primary barrel nut 280. Beveled or tapered shoulder 268 of barrel 230 is under torqued contact with internal beveled or tapered shoulder 316 in secondary barrel nut 300. In one embodiment, beveled or taper shoulder 292 and 256 are formed with an angle of 10-60 degrees. Beveled or taper shoulder 268 and 316 are formed with an angle of 10-60 degrees.
FIG. 8d is a cross-sectional view of primary barrel nut 280 and secondary barrel nut 300 with barrel extension 254 and beveled or tapered shoulder 256. In particular, beveled or tapered shoulder 256 is under torqued contact with internal shoulder 292 of primary barrel nut 280. Beveled or tapered shoulder 268 of barrel 230 is under torqued contact with internal beveled or tapered shoulder 316 in secondary barrel nut 300.
As shown in FIGS. 8a-8d, by nature of internal beveled or tapered shoulder 316 contacting beveled or tapered shoulder 268, barrel 230, and correspondingly bore 242, is centered and aligned with upper receiver 202. The proper alignment between upper receiver 202 and bore 242 of barrel 230 avoids wear on the bolt, catastrophic failure of the bolt, and un-torquing of the barrel extension due to vibration and heat expansion. The proper alignment between upper receiver 202 and bore 242 of barrel 230 reduces harmonic vibration, while increasing dynamics, durability, and accuracy of sporting rifle 200. The double barrel nut assembly 280, 300 is applicable to most, if not all, firearms with a removeable barrel.
While one or more embodiments have been illustrated and described in detail, the skilled artisan will appreciate that modifications and adaptations to those embodiments may be made without departing from the scope of the present disclosure.
Patent Application
20230194202
