Problem with X Valve on Tac One

[custar]

I am working a friend's Tac One. The Xvalve is pretty much standard with L10 bolt, ULT on/off (currently with 2 shims), and nothing out of the ordinary. I have a 4500 psi tank hooked up with an output of ~850 psi. Whenever, I pull the trigger, there is a four to six shot runaway full auto I cannot control. I have adjusted shims up and down with no effect. I tried a RT on/off in the valve with an unexpected result. There is no more runaway; instead, it takes the valve about a full second to recharge. I replaced the RT on/off in my Xvavle and put that into the Tac body. It works exactly like it should, so I don't think there is any physical problem with the sear (none I can see with my eyes, at least). My friend's Tac One is fairly new, but I can't see that in and of itself causing the runaway full auto.

What am I missing here?

custar

[BigEvil]

"NEW" as in "New from the factory" or "New, just put it together from parts"?

Could have the wrong on/off pin in there.

Could also have the reg pin or the on/off pin hanging up. Old, dry or swollen orings can do funky things.

If you can measure the on/off pin, great. Look up the proper specs in the sticky at the top of this forum.

Secondly, take the reg pin out, inspect it for damaged orings. If they are bad, replace them, and in both cases LUBE THE LIVING HECK OUT OF IT. Replace it, put it all back together and try it out. See if its any better or act differently.

You should also double check the spec on the trigger rod.

[custar]

The Tac One was bought within the last year and used for only a game or two.

Visually, I didn't see any damage to the o-rings, but I will double check with my loupe this p.m. I don't think it is the wrong pin. I actually tried an emag valve with an emag pin, and it worked in the Tac One set up without a problem. Strange.

Thanks. I will try those suggestions.

custar