It might be mounted with staking or soldering. A small merchandise is that the pin which retains the firing pin spring cap tended to operate loose, and needed to be tapped back in place as a person observed it job from your rear of the bolt. Winchester replaced that pin https://highimpactrounds.com/product/winchester-target-7-62x39-123-gr-fmj-2355-fps-20-rd-box/