Breech bolt for firearm
AssigneeMichael H. Blank
InventorMichael H. Blank
Life of this patent
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Abstract
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 face so that a rearward face of the respective lug is taller than a forward face of the respective lug. In another aspect, at least some of the lugs on the lug portion of the bolt have tapering side faces so that a rearward face of the respective lug is wider than a forward face of the respective lug.
Claims10
A breech bolt assembly for mounting in a firearm for loading a cartridge in a firing chamber of the firearm prior to firing a projectile from the cartridge and extracting a 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 substantially parallel to the longitudinal centerline, said lug portion including a plurality of spaced lugs extending outward therefrom, at least three of said spaced lugs being of substantially equal height and equally spaced, a cartridge recess at a front end sized and shaped for holding a rearward end of the cartridge therein, an extractor cavity extending rearward from the cartridge recess, and an off-center longitudinal hole at least partially aligned with the cartridge recess;
- an extractor pivotally mounted in the extractor cavity and biased to hold the cartridge in the cartridge recess;
- and
- an ejector pin slidably received in the off-center longitudinal hole, the pin being biased to eject the shell casing from the cartridge recess;
- wherein at least two of the plurality of lugs on the lug portion of the bolt have:
- a flat top surface portion extending from a rearward face of the respective lugs, the rearward face having a quadrilateral shaped perimeter with a curved bottom edge, an arc of the curve extending toward a top edge of the rearward face, the flat top surface portion having an arcuate leading edge;
- and
- a rounded tapering outer face extending from the arcuate leading edge of the flat top surface portion along more than 25% of a longitudinal length of the respective lug to a forward face of the respective lug, the forward face having a rounded top edge, the rearward face of the respective lug being taller than the forward face of the respective lug;
- and
- wherein the rounded tapering outer face of each respective lug has an outer radius that is less than a radial distance between said centerline and the corresponding outer face.
Dependencies are inferred from the claim text.