It may be fastened with staking or soldering. A little product is that the pin which retains the firing pin spring cap tended to work loose, and needed to be tapped again in place as just one noticed it project with the rear on the bolt. Winchester replaced that pin https://highimpactrounds.com/product/winchester-aa-xtra-lite-12-ga-2-75-in-1-oz-8-lead-1180-fps-25-rd-box/