Help!!! Unexplained Barrel leakage

[naDz]

I'm not what you would call and automag Guru and i have a probkem with my mag that i cant figure out.... first off i,m running my mag on CO2 but i got an expansion chamber. When i gass up my gun it leaks down the barrel. Ive repaced the power tube o-ring along with all the others. i really need to get this gun running could someone please help.

[FrAuStY]

First try a shorter powertube spacer.. the o-ring and the base of the powertube isn't creating a good seal. causing leakage down the barrel. You can get a spacer kit from AGD for like 15-20$