It could be set with staking or soldering. A little merchandise would be 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 noticed it project through the rear from the bolt. Winchester replaced that https://highimpactrounds.com/product/winchester-ammunition-long-beard-xr-20-gauge-3in-6-1-1-4-oz-shot-lok-lead-1000fps-10-rd-box/