Leaking bettween two halves of valve.

[Blennidae]

Oops, I thought it was a retro. They have an exploded diagram of the A.I.R valve as well. Couldn't hurt to check.

http://www.airgun.com/downloads/valveexplodedview.pdf

[Butterfingers]

Turn that velocity down, If it is in too far it will start spewing air out of the back.

An on off leak can be easily misconstrued as a leak between the halves. Check your urethane on off o-rings and replace the teflon ones.

[PyRo]

Do what butterfingers said.
The AutoMag, Minimag, or whatever is says on your valve will not alwys line up perfectly. This is normal, with wear in the z-grove on the bodyrail. As long as it isn't rediculously out of line due to a missing pin in the back half of the valve you should be fine like that. Leaks from the on-off could be fairley easially mistaken as from between the valve halves. That fat o-ring should almost never need to be replaced.

[Aliens-8-MyDad]

i replaced all my on/off o-rings too, still does it. im just gonna fill my tank.

[[M@g_D@ddy]]

on that fat yellowish seal (reg seal, not the o- ring that goes around the back half of the reg) there is a hard and a soft part. make sure the hard part is in the back half of the reg, and the soft part is pointing towards the front of the 'gun. hope this helps.