US Patent 10578379 Firearm bolt carrier assembly kit

The present disclosure provides devices, systems, and methods for assembling a firearm bolt carrier assembly. For example, in various embodiments, a bolt carrier assembly kit comprises at least one actuation mechanism, and a bolt carrier, wherein the bolt carrier comprises an outer surface, a manual bolt actuator pocket disposed on the outer surface, and an actuation key buttress disposed on the outer surface and having a front end, a back end, and a bore extending from the front end along an axis at least partially towards the back end.