valve sliding back and leaking :-(

[RoLLonBombs]

hey guys im new here :-p but im sad to say its because i have a problem with my mag, i bought it about 3 years ago and have not found the time to play, now that i have the time i go to play and theres a leak i check it out and the problem seems to be after i gas up ad fire a few rounds, the valve is sliding back just a tiny bit and air is leaking out the back of the gun to stop it i have to shoot to release pressure and push the valve back in then its good for a few more shots, i guess maybe the rail or somthin is aa bit worn? and the thumb screw isnt holding as it should im gonna put a small bsing around it and make the screw have a tight fit into the grip, but if this has happend to someone else and they know how to fix it another way, or whats causing it plz let me now ive been to 4 diff shops, and apparently since i last was in the paintball scene till now the automag has gone from top shelf to unheard of, i actuall asked a kid at the feild i play and he said whats an automag...this is very frustrating well
thanks in advance

[st6212]

If your referring to the 1mm(?) gap between the mainbody and the valve that is normal. Even with a rail bushing and tightening the rear thumbscrew, you will still have a slight gap after firing a few shots.

Since you haven't touched your mag for some time. Did you put a few drops of oil into the air inlet before gassing it up? Also, if the air is venting out the back, try dialing down the velocity adjuster.

[ahellers]

and put a bunch of oil on the on off as well.
t

[pump]

my mag would sit further back when i used an RT frame

it would leak down the barrel...badly

i used a shorter powertube spacer and it stopped the leak

[RoLLonBombs]

i havnt took it out and played with it a whole day but i made my own bushing to go around the thuimb screw that stop right b4 the threads so it wouldnt slide back so far
and i shot like half a hopper thru it, fast.. no leaks or any sound hinting to a problem, going again in 2 weeks, hope its fixed for real
thanks for the suggestions guys

[Pneumagger]

haha, your rail bushing fell out.

[RoLLonBombs]

up, didnt work for the long haul what else??

[Beemer]

As has been said already. This is what you need if it isnt there.

http://store.airgun.com/index.cfm?fuseaction=catalog.prodInfo&productID=403&categoryID=92

http://store.airgun.com/images/product/403.jpg