Had a model 66-2 (the 2 is stamped over a 1) lock up last night shooting some .357 that I had laying around. The ammunition is Lellier and Bellot .357 magnum and is marked FMJ 10.25 g 158 grs. I have shot quite a bit of 38 special with no problem but the above ammo locked up the revolver so I could not open the cylinder, pull the trigger or pull the hammer back. Eventually, I was able to get the trigger to pull back and discharge the next round. Unloaded the revolver and took everything home. What caused this problem and what was the actual problem? (Other than the obvious that everything was locked up...) Any help would be appreciated, do I need to send back to Smith and Wesson to ask for their advice/help?