So I picked up one of the Rock Island 2011s in 9mm. I scoured the country and finally found a place that makes a Clark/Para threaded barrel for it. When it arrived, it fit wonderfully. The gun is smooth as glass when it is being cycled empty, and I can't feel anything binding or rubbing. However, when I try and run a magazine, it fails to go into battery about every 2-3 rounds. I have tried multiple different handloads and factory loads that work fine in all other guns, and also gauged them to make sure it wasn't the ammo. Some rounds will go into battery and fire just fine with a remedial tap at the back of the slide. Some of them will completely jam up the gun. Not being a 1911 guy myself, I'm not sure where to even start looking as far as tolerance wise goes.
Ideas?