Ok i pulled my 98 custom out of the closet after a 2 year sit, tired to fire off some rounds and have some issues.

I have a expansion chamber and a responce trigger.

When the barrel is off it fires full auto pretty well, if I fire too fast the bolt will not go back far enough for the trigger to release it, so I have to pull it back. This is with the velocity screw all the way in, if I move it out and try to fire(with the barrel off) it just ratchets down like it ran out of air.

With the screw all the way in or out and with the barrel on I get one shot out of it, the bolt does not go back enough to latch, or go back at all really.

I just ordred a part kit and will replace everything in there, but if you can think of anything else?

Muppet wrote: Well looks like the 2 bolts holding in the valve are missing, could that cause this?

Yes! OcXf said it correctly. You probably don't need to replace everything.  A few drops of oil in the ASA; a drop or two on the hammer "O" ring and the same on the forward bolt "O" ring. Couple of drops on link rod.

If the "O" rings show any flat spots from sitting in place for so long, you will likely have to replace them. Marker "O" ring kits available from many on-line stores...and Tippmannparts.com.