| 摘要 |
A firearm including a receiver, a barrel, a breech bolt assembly, and a trigger assembly. The bolt assembly has a bolt including a body portion, a lug portion, and a firing pin bore. The lug portion includes outward extending lugs, a cartridge recess, and an off-center hole. The bolt assembly also includes an extractor and an ejector pin. At least some of the lugs on the lug portion of the bolt have a tapering outer surface so that a rearward surface of the respective lug is taller than a forward surface of the respective lug and at least part of each tapered outer surface is taller on one side of a circumferential centerline than on another side of the circumferential centerline. |
| 主权项 |
1. A firearm for firing a projectile from a cartridge including a shell casing having a hollow interior, propellant in the interior of the shell casing, and the projectile mounted at a forward end of the shell casing, said firearm comprising:
a receiver having a cavity therein and a barrel interface at a forward end thereof, the barrel interface including a bolt interlocking chamber and a plurality of receiver lugs spaced by gaps and extending inward behind the bolt interlocking chamber; an elongate barrel mounted on the barrel interface for directing the projectile forward when fired from the cartridge, the barrel including a firing chamber at a rearward end for holding the cartridge prior to firing the projectile and for holding the shell casing after the projectile is fired, the firing chamber being positioned in front of the bolt interlocking chamber; a breech bolt assembly mounted in the receiver cavity behind the barrel interface for loading the cartridge in the firing chamber from a cartridge source prior to firing, and extracting the shell casing from the firing chamber after firing, the bolt assembly comprising:
a bolt including an elongate cylindrical body portion having a longitudinal centerline, a lug portion extending forward from the body portion, and a firing pin bore extending through the bolt parallel to the longitudinal centerline, said lug portion including a plurality of lugs extending outward therefrom, a cartridge recess at a front end sized and shaped for holding a rearward end of the cartridge therein, and an off-center longitudinal hole at least partially aligned with the cartridge recess, said plurality of lugs being spaced to correspond to the gaps between the receiver lugs so that the plurality of bolt lugs can slide forward through the gaps and rotate about the centerline of the body portion to align at least some of the plurality of bolt lugs with at least some of the plurality of receiver lugs;an extractor pivotally mounted in the extractor cavity and biased to hold the cartridge in the cartridge recess; andan ejector pin slidably received in the off-center longitudinal hole, the pin being biased to eject the shell casing from the cartridge recess; and a trigger assembly including a firing pin slidably received in the firing pin bore of the bolt and aligned with the cartridge when received in the cartridge recess and firing chamber for initiating firing of the projectile from the cartridge; wherein at least some of the plurality of lugs on the lug portion of the bolt have a tapered outer surface so that a rearward surface of the respective lug has a greater radial height than a forward surface and at least part of each tapered outer surface has a greater radial height on one side of a circumferential centerline than on another side of the circumferential centerline. |
