It is not necessary to tight wiggling rod in bolt carrier hole.
Here is the AK Patent:.
http://kalashnikov.guns.ru/patent.html
1. The automatic weapon "Kalashnikov's Automatic machine", containing a receiver, the with great dispatch-trigger mechanism including a cock also whispered automatic release with the automatic platoon, the locking mechanism including a rotary shutter with the drummer, placed in a bolt carrier established on directing receiver and supplied with a back ledge directing a receiver, cooperating with a cock, gas mechanism with a gas tube and the piston which rod