Installed a new MGM barrel on my Contender pistol, could not open after installed nor can I remove barrel after taking pin out. When installing pin went right in, felt everything was good. Have used 2 other barrels (TC) with no problems. With pin out cannot line up hole to put pin back in.
Any suggestions?
Thanks Charlie

Possibly an older single leaf breach lock on the frame with older barrels? If so, the new barrel with the two piece lock may need to be fitted to your frame? I had that happen once. The Bellm TC website was a great help. Eventually it only needed a bit of polishing of the top of the breach block. Scary at first but easily remedied.MK

Sounds like a locking lug issue to me , call MGM, they will send you a couple of sets to swap your original ones out.