Air leaking down barrel after a few shots

[Normalcy]

Howdy all. Just got my first mag today. It's a mini-mag with x-valve/level 10 upgrade and a ule trigger frame. Aired it up to an 850psi output HPA and it fired like a dream for a few shots, then it just leaked ALL of the ait out the barrel as though it wasn't re-cocking. Tried pushing the bolt back but no-joy. Checked the old posts and some mention a min pressure of 900 PSI, my tank was just under 1000 when I started firing. Could this be my problem? Any help would be appreciated. p.s. other than "autolube" which I don't have, what oil would you reccommend?

[athomas]

Try filling your tank.

Are you sure you don't mean ULT trigger upgrade instead of ULE trigger frame. Too many shims in the ULT assembly will cause the problem you are experiencing.

An improperly sized level 10 carrier could also give you grief. Sticking means too tight. Resetting but leaking means too loose. Make sure you don't have too many shims in the powertube.