Sturm, Ruger & Company, Inc. announced the availability of three, AR-style upper receiver assemblies featuring the innovative two-stage, piston driven performance of the SR-556 family.

Addax Tactical's AR Gas Piston Upper, the ATAC-GPU (Advanced Tactical AR Carbine Gas Piston Upper), utilizes a specially designed, self regulating, long stroke piston system, ...

Opposed-piston engines are not a new concept. The original idea dates back to 1882 and James Atkinson, who developed the Atkinson differential engine.

It took a partnership with Wolf Ammunition that imported T91 upper receivers into the United States, under name “Wolf A1” for interest to be truly revived in the T91 piston system.

Unveiled at the Defence & Security Equipment International (DSEI) 2023 defence exhibition in London, the NARP is a short-stoke gas piston-operated rifle. Built with an upper and lower receiver ...