The Mauser Selbstlader M1916 (German for self-loader), officially known as the Selbstlader-Karabiner Mauser M 1916 by the Ballon-und-Zeppelin-Truppe or the Fliegerkarabine 15 by the German Air Force and occasionally called the Mauser Selbstlader M1915, is an early German semi-automatic rifle.
The Selbstlader was issued in 1916 with multiple 20-round magazines; the rifle was able to put out volumes of fire impressive for its time. However, only 1,000 were made due to high manufacturing costs, reliability issues and its punishing recoil force. To replace the weapon, Mondragón rifles were acquired by the German army and pushed into service. Interestingly enough, the Mondragóns were plagued with even more problems than the already unreliable Selbstladers, but the Germans decided to go ahead and use them anyway. Every Selbstlader was replaced by two Mondragóns, and by then, the Selbstladers were largely phased out of service.
The Selbstlader is a development of the older M1906, 06/08 and 10/13 self-loading rifles. The magazine catch was located in a rather interesting place on the weapon; behind the trigger guard. Reloading the weapon was a complicated process; the magazine release had to be pressed, and the trigger guard swung down slightly for the magazine to be removed. Putting the magazine back in caused the bolt to slam forward and bring the first round into battery. The rifle used a flapper-locked recoil operation. The barrel, unlike most recoil-operated weapons, does not move; instead, a cam plate situated in the rear receiver helps unlock the bolt, along with two large flapper locks.
The Selbstlader had two known variants; a rifle and a carbine, both of which are functionally identical. The carbine version of the Selbstlader can be differentiated by a small vertical foregrip situated in front of the magazine well, and is the variant that is more commonly seen.