Abstract: A frame lug for a firearm having a receiver or barrel hingedly mounted to a frame is provided with a tension post having an external thread that adjustably engages with an internal thread of a vertical bore in the frame lug. The tension post provides a height adjustable top surface upon which the receiver or barrel rests when in a closed position and maintains a tight metal-to-metal connection to improve precision of fitting together the receiver or barrel and the frame. Firearms may have the frame lug installed therein or be retro-fitted with the frame lug. In a retro-fitting method, the firearm's frame lug is removed, a threaded vertical bore is machined at least partially into the frame lug, and an externally threaded tension post is adjustably engaged with the vertical bore such that a top surface of the tension post provides a tight fit with the receiver or barrel.

Abstract: A frame lug, firearm and method for retrofitting a firearm having a receiver or barrel hingedly mounted to a frame. The frame lug is removed from the frame. A vertical bore having a threaded internal surface is machined at least partially into a main body of the frame lug. A tension post having a threaded external surface is fabricated and adjustably engaged with the threaded internal surface of the vertical bore to provide height adjustment of a top surface of the tension post above the main body. A horizontal bore having a threaded internal surface is machined through a side surface of the main body and operatively connected to the vertical bore. A lock screw having a threaded external surface is fabricated and adjustably engaged with the threaded internal surface of the horizontal bore to engage and lock the tension post in place.

Abstract: A semi-automatic rifle kit comprises a receiver; first and second bolt assemblies that can be interchangeably inserted inside the receiver when no barrel is coupled to the receiver; and first and second barrels that can be interchangeably coupled to the receiver when no bolt assembly is inserted inside the receiver. The first bolt assembly can be inserted inside the receiver when the first barrel is coupled to the receiver, but not when the second barrel is coupled to the receiver. The second bolt assembly can be inserted inside the receiver when the second barrel is coupled to the receiver, but not when the first barrel is coupled to the receiver. The first bolt assembly and the first barrel are designed for use with a first type of cartridge, but not a second type of cartridge. The second bolt assembly and the second barrel being are designed for use with the second type of cartridge, but not the first type of cartridge.

Abstract: A method and a device for retrofitting existing autoloading pistols having a one-piece bolt stop pin. The first step of the retrofitting method is to cut off the original bolt stop pin and then machine a threaded bore in the remaining shaft. In addition, an extension which mimicks the original bolt stop pin configuration is manufactured. The extension has a threaded end which is screwed into the threaded bore in the remaining shaft portion of the original bolt stop pin. To disassemble a pistol having a two-piece bolt stop pin, the bolt stop pin extension is unthreaded from the remaining shaft portion using a screwdriver or similar implement. Then the loose extension is pulled upwards and out of the receiver, freeing the bolt to be pulled rearward and out of the receiver. The pistol is further modified by rounding the sharp upper corner of the hammer, e.g., by machining a smooth radius.