It might be fastened with staking or soldering. A small product is that the pin which retains the firing pin spring cap tended to operate free, and had to be tapped again in place as a single observed it task with the rear in the bolt. Winchester replaced that pin https://highimpactrounds.com/product/winchester-xpert-20-ga-2-75in-6-3-4-oz-1325-fps-game-load-25-rd-box/