ULT leaking issue

[minimag1]

Hi all,

I got a used Tac-One with a ULT installed. The gun was in really rough shape so I got a oring kit from AGD and replaced every oring in the whole gun including all the orings, except the micro buna oring in the ULT rod, on the ULT.

Now, the gun fires fine but the oddest thing happens. If the gun is just sitting there it's fine, no leaks. But If I pull the trigger and hold it I hear leaks coming from the ULT. What doesn't make sense to me is, how can it leak with the trigger being held back but not with the trigger open? If I remember my automag troubleshooting with the trigger pressed that seals all the air into back of the X-Valve. But I get a leak from the on/off. But with the trigger open, and air now also in the chamber and behind the bolt I get no leaks.

If anyone can give me a troubleshooting tip to figure this out I would be eternally grateful. I cannot figure this out.

[TheRealKaz]

This is a common leak. Typically if you hold the trigger and it leaks it's either the trigger on/off (ULT in this case) o-rings or a seal in the valve it's self.

If the gun leaks when the trigger isn't pressed, it's typically your carrier o-ring in the power tube.

It's normally the on/off so I would start with replacing all of those o-rings before cracking the valve open.

[athomas]

The leak is probably coming from the front, but may sound like it is coming from the ULT. A leak that occurs when you hold the trigger in, but not when it's released, is caused by the top oring on the on-off not sealing. It could be that you just need to remove one or two of the ULT shims.

[TheRealKaz]

That's right, too many shims can cause a leak as well. Forgot about that.

[going_home]

Change the o ring in the ULT.