If you're having any problems what-so-ever with your Pietta shooter and your gun-monger doesn't get it right email Mr Puzzo at Pietta in Italy. Address is: alfpuzzo@tin.it I've had great success through him.
On the other hand I have an ASM that was a gift that I have ruined the cylinder because it sat for 15 years after being fired with the nipples tight. I don't know how many wrenches I broke but after I gave up on the wrenches and drilled an access hole, I broke 3 "easy outs" and still do not have the remnants of the nipple out.