I have one also but my problems are different. Mine sometime locks up unless you cock with real authority. I had a buddy who is a watch repairman go over mine (he has an original Starr) and he told me of their "eccentricities". Firstly, it sounds like the hammer is not reaching the nipples. You are seating them deep an tight, right? This is a problem that can only be solved by longer nipples, i.e., bushing yours. The American replacement nipples are almost always too short for the Piettas IMHO. I replaced the nipples on a Remington by Pietta with MSN stainless nipples and nary a cap would pop! Back to the factory nipples for me! Finally, the hammer falling to half cock is serious and needs gunsmith attention and it sounds like the sear engagements need reworked. I'd send it back if possible and let the distributor worry about it. Mine is deadly accurate but ungainly and heavy. I hope I helped somewhat.
