You will be glad you got the Sharptail. I had a .410 Ringneck that worked when it liked to. I believe the trigger springs they used were bad at best and part of why it was dropped from their lineup. CZ USA was kind enough to replace my Ringneck with the Sharptail as they said it was not "repairable". The gun was about 2 weeks old, couple hundred rounds through it.
Ditto on you being lucky to have acquired a Sharptail. I had the same experience, Ringneck target would fire only about half the time. CZ said it was not repairable and replaced it with a new Sharptail target. So far so good. The Ringneck used questionable leaf style hammer springs and the Sharptail was upgraded to coil springs. Good luck.