Squib308 reported: concur seems like an ammo issue. Probably the brass is bulging? have you inspected the winchester brass prior to vs. after firing? MGL Chapter one hundred forty said: “Significant ability weapon”, any firearm, rifle or shotgun: (i) that may be semiautomatic with a fixed large capacity feeding gadget; https://highimpactrounds.com/product/mossberg-590a1-spx-12-ga-20in-8rd/