I have a love hate relationship with my Diana 340 N-Tec. It's beautiful, well made and inconsistently accurate. I mounted a scope With the angled shim type adapter to compensate for the known barrel droop. I have tried many pellets. It is a 22 cal. I have great sessions and sessions when I can't hit much. Any advice for me? Is there some maintenance item I'm missing? What is your experience with this gun?