I have a p-90 and the only problem I have had is with imported ammo, sometimes it misfires. I called Ruger and they sent me a new main spring, that helped some, but it still happens. Ruger wants me to send them the gun so they can fix it but I have not done it yet. So far they have been great to deal with. I shoot with a couple of other guys who have the same gun and they have no problems with any type of ammo. I do like the gun just need to send it back and get it fixxed