The Winchester self-loading rifle, caliber .351, is sometimes used as an auxiliary weapon in aircraft. The action of the gun is semi-automatic as the name implies, and it is fed from a detachable box magazine holding five cartridges. One cartridge may also be carried in the chamber, giving a total of six shots.

The magazine is removed by releasing the magazine catch which extends from the lower edge of the right-hand side of the receiver, and is then loaded and replaced in the gun. .

The first cartridge is then fed into the chamber by pressing in on the rod extending from the f orward end of the forearm. The gun will now fire every time the trigger is pulled until the magazine is empty.

The safety consists of a small pin.located in the forward part of the trigger guard. The gun is safe when the safety extends out from the right-hand side of the guard, and is made ready to fire by pressing the safety to the left.