It could be fastened with staking or soldering. A little item is that the pin which retains the firing pin spring cap tended to operate loose, and had to be tapped again in place as a person noticed it job in the rear in the bolt. Winchester replaced that pin https://highimpactrounds.com/product/winchester-super-x-16-ga-2-75-in-6-1-oz-1165-fps-game-load-25-rd-box/