It could be fastened with staking or soldering. A little product would be that the pin which retains the firing pin spring cap tended to work free, and needed to be tapped again in place as 1 noticed it job from the rear from the bolt. Winchester replaced that pin https://highimpactrounds.com/product/aguila-308-win-150-gr-fmjbt-2750-fps-20-rd-box/