This is the complete patent for the Barrett 50Cal BMG.

It includes all drawings, and assembly literature.

From the abstract:

A repeating firearm, includes a bolt carrier and bolt assembly which are movable relative to each other to provide for locking and unlocking the bolt with respect to the barrel breech.An elongated bearing plate is supported by the bolt and movable with the bolt to maintain a cartridge to be next inserted into the barrel chamber in a predetermined position until the bolt is substantially fully retracted to prevent premature movement of the cartridge upon movement of the bolt carrier only.

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