English: en:SIG MKMSThe delayed blowback made use of two-part bolt designed by Gotthard End. In this system, the bolt body was allowed to recoil for a very short distance after the bullet was fired. After this it was stopped and secured by striking the rear edge of the ejection port and becoming caught on a catch. Next the rear part of the bolt (second part) was allowed to recoil freely under the inertia which provided a necessary delay for bolt to open. After a certain distance of recoil, the rear part of the bolt struck the bolt body (first part), unlocking it from the receiver. Once unlocked, the two-part bolt group is free to recoil and cycle the action. Upon closure of the bolt, the rear part of the bolt forces the front part to tip its rear end up and make it ready for locking after next discharge. Thus the cycle repeats and automatic fire is sustained at least until you run out of ammo.