leaking, sputtering, and double firing!!

[Cardinal_Biggles]

My friend just bought an older level 7 pf mag, and it's acting really wierd. It's got the old style bolt with the nose sticking out, but it looks like the valve hasn't been messed with at all. The trigger rod also looks good as compared to mine. If you pull the trigger back all the way and release it quickly, it's fine, but if you leave it in the middle of the pull for any time, it starts to leak, then on the next trigger pull it fires twice. sometimes it just fires twice regardless of what you do. I know it seems like short-stroking, but doing the same thing with my 'gun doesn't produce this effect. I've tried larger spacers (but not shorter ones), and i've swapped o-rings, all to no avail. I'm just wondering if there's anything painfully obvious that I didn't see.

[PyRo]

Fireing twice is usually a result of a worn bolt or sear.

[Cardinal_Biggles]

That's what it seems like. Guess we'll have to make a call to AGD on mon to order a few things.