Excerpt - page 38: "... The AKMS rifle incorporated delayed-blowback operation in place of the traditional Kalashnikov gas operation. Delay was provided by the double-shouldered block shown ..."
Excerpt - page 68: "... 68 THE BIRTH OF THE AK 2 The assault rifles of Kalashnikov (with pressed breechblock unit), Dementyev and Bulkin attained the closest ..."