Patent ID: 8141287

Claim:
A rifle frame comprising: a receiver having an inner surface defining a chamber that extends from a rearward opening to a breech passage, the rearward opening and the breech passage being disposed coaxially along a central axis of the chamber and the breech passage being smaller in diameter than the chamber, and including a lower opening extending radially from the chamber through a lower side of said receiver rearward from the breech passage; a barrel enclosing a bore extending from a breech end of the barrel to a muzzle end of the barrel, said barrel including an externally-threaded portion smaller in outer diameter than the breech passage of said receiver and disposed proximate the breech end of said barrel, a shoulder larger in diameter than the breech passage and disposed substantially adjacent to the externally-threaded portion, and a feed ramp extending downward and rearward from the breech end of said barrel adjacent to the bore; and a barrel nut having an internally threaded opening dimensioned to engage the externally-threaded portion of said barrel, the barrel nut being larger in outer diameter than the breech passage of said receiver, wherein the externally-threaded portion of said barrel is inserted through the breech passage of said receiver and said receiver is clamped against the shoulder of said barrel by threaded engagement of said barrel nut onto the externally-threaded portion of said barrel to sandwich the receiver between the shoulder and the barrel nut.