On the advice from another member:

I bought one of these last year .177 cal. Quite happy with it at first, periodic check with the chrono it settled down to a good 5fpe. A few thousand shots later and its not grouping very consistantly and the power has dropped to just under 4fpe AA field and the spring during cocking sounds like a rusty steel door.

Is this normal?

Is there a HW45 tuner on here?
John