Squib308 claimed: agree seems like an ammo difficulty. perhaps the brass is bulging? have you inspected the winchester brass right before vs. right after firing? Choke: choke is another discussion than shotgun shells, but what choke you might be working with must sync with whatever projectiles you happen to be https://highimpactrounds.com/product/mossberg-590a1-spx-12-ga-20in-8rd/