Originally Posted by madmikeb

I just had the same problem with a PC 686+ with the vent rib. It would cycle fine empty, but when loaded it would lock up solid every few shots.

On inspection, I noticed with the action at rest and the cylinder open, the hand wasn't at the bottom of the window and protruded past the recoil shield. All my other Smiths, when at rest, the hand is at the bottom of the window and even with the recoil shield. I think the problem lies there.

It went to Springfield a couple weeks ago and I'm waiting for its return. I wonder if you check yours out it will have the same problem.