Background: Some years ago I got an 1851 Pietta and shot it now and then. The last time I shot it I had a terrible problem with it sucking caps and getting into the action, and to make things worse, I didn't clean the innards. More time passed, I got it out, cleaned everything out, the innards looked okay (though worn in some places), and it wouldn't go into half cock. More time passed, and a couple of weeks ago I decided to see if I could fix it. I got one of the parts kits from Cabela's that contains a hammer, bolt, bolt spring, trigger, hand, and mainspring. I've just spent several frustrating hours with it. Disassemble, assemble, try it, iterate. Here's the best I've been able to do after trying various combinations of the old parts and new parts ... The new trigger is simply too long and won't fit in the trigger guard!! I decided not to reshape it at this point. The new hand seems to be too long and with it the cylinder just doesn't lock up anywhere close to correctly. The new bolt fits okay, but the old one seems to fit the cylinder slots a bit better. So the parts I'm now using are: New hammer New bolt spring New mainspring Old hand Old trigger Old bolt This has resulted in things ALMOST working: It goes into half cock just great!! It full cocks. The trigger works great BUT It does NOT lock up in full cock. The (old!) hand is rotating the cylinder just a bit too far. What I've discovered is that if I SLOWLY bring it to full cock, I hear a click, and then when I release the hammer the cylinder is locked up correctly. But if I cock it by pulling it back all the way quickly, the cylinder is rotated too far and doesn't lock up. If I cock it by pulling back all the way SLOWLY, it clicks like it's full-cocking, and then if I release it the hammer moves forward just a hair and click fully into locking the cylinder in the proper position. What are your thoughts on the best way to adjust this to get it right? Any insight will be appreciated. Just not sure what "minor" modifications to this setup I should try, or if I should put all the new parts into it and then mess with modifying those as necessary.