Squib308 said: agree seems like an ammo concern. perhaps the brass is bulging? Have you ever inspected the winchester brass in advance of vs. soon after firing? I'll almost certainly hearth it several periods with buddies it to try out the pistol grip, then change it with one thing greater. https://highimpactrounds.com/product/mossberg-590a1-tactical-12-ga-20in-8rd/