Classic mag venting out barrel

[Cielmerlion]

Hiya!

I have just built a micromag pistol with a classic mag valve and single benchmark trigger. A bit of a disclaimer, its my first mag. When I hooked up the co2 to it it started venting out of the barrel until it is empty.

So, Im wondering what can cause this? It did have a double trigger which I swapped for a single if that makes any difference.

Thanks for any help!

[OPBN]

Did it air up properly with the double trigger? If so, check your trigger rod length. Should sit a credit cards thickness from the back of the trigger when its aired up.

[Cielmerlion]

Ok, I put the double trigger on and instead of quickly venting I get a very slight hiss. Pulling on the trigger made it vent a little bit harder and if I pulled on it hard stopped the venting more or less. When aired up the double trigger has about as much room as you say between it and the trigger rod.

[Cielmerlion]

Oh, and the increased venting from pulling the trigger stayed that way after I let the trigger go.

[Cielmerlion]

Put in a longer spring from the original Rt valve that came with the mag and it vented quickly. Pulling on the trigger would stop the venting.

[OPBN]

Have you oiled it?

[Cielmerlion]

I put about 5 drops of oil through the ASA and adjusted the rod length. Now while it does still leak through the barrel it managed to fire off a shot like thing while still leaking.

[Cyco-Dude]

the power tube o-ring is bad, replace it. then, watch this video!

[athomas]

It is related to the powertube oring. Replace that oring. If it still leaks, install a shorter powertube spacer.

[Cielmerlion]

Thabks for the help! One last thing, ive not replaced eother of the things since i dont have the spares, but i thing it might be a spacer problem. If its venting and i put pressure on the valve back inwards it stops venting and can fire. Would that mean i need a thinner spacer?

[Cyco-Dude]

Thabks for the help! One last thing, ive not replaced eother of the things since i dont have the spares, but i thing it might be a spacer problem. If its venting and i put pressure on the valve back inwards it stops venting and can fire. Would that mean i need a thinner spacer?

it could mean your bolt and / or sear are worn out.

[athomas]

Thabks for the help! One last thing, ive not replaced eother of the things since i dont have the spares, but i thing it might be a spacer problem. If its venting and i put pressure on the valve back inwards it stops venting and can fire. Would that mean i need a thinner spacer?

Yes, a shorter spacer allows the chamber pressure to push the oring farther forward to rest against the back of the bolt stem. If it used to work before, either the oring has changed due to age, or the sear has worn and is allowing the bolt the sit farther forward. If a slightly worn sear isn't causing issues with multiple bursts when firing, then you can compensate using a shorter spacer.