i got a project rifle its a jumbo same as np 500 action full 20 inch barrle with large shroude has end cap cover for 1/2 20 has after market band and has a up greaded carbon tank has a super small leak i not found yet goes from 250 bar to down to 100 bar but takes weeks to do that has a brand new jumbo stock on it never mounted this is a progect gun shoot fine i test fired it it holding air at 100 bar been holding at 100 for over a week there some little leak some where on it