I fired 220 rounds with zero problems using Glock 33 round mags and Magpul (for Glock) 21 round mags. 4 brands of 115 gr. ammo. Feeds very smoothly. Great trigger. Very little take up and No creep. Not like a standard 10-22 trigger at all. The barrel fits 100% tight. It has a feed assist ramp above the chamber which prevents nose up jambs. The overall design requires very little lubrication. The bolt assembly weighs 23.7 oz. A bit more than an UZI bolt or an AR 9mm bolt + buffer. Also the Ruger thumps your shoulder less than an AR 9mm. When cleaning 95% of the dirt can be removered from the gun without removing the bolt. To remove the bolt requires unscrewing three #10x32 screws and pushing out two pins. The screw retaining the bolt knob must be installed tight or it will start backing out during firing. I had switched the knob to the left side before I went and after firing 220 rounds found the screw had become a little loose. It did not affect the operation of the gun. I am very impressed with this new PC9. Very fun to shoot. Also a no nonsense,dependable, military style carbine.