Bolt wont budge

[benzy2]

Ok so heres the deal. A budy of mine came over and said he had problems with his mag. I figured I could help him out some or at least try. I get down to the garage and hook up my air tank. The gun goes into full auto with just a tap of the trigger. I take the gun apart and the sear looks rounded off and I figured that could be the problem. So now Ive got some mag parts laying around including another sear so lets try that. I was starting off working from an RT rail and sear. The only spare I had was a classic but I had a classic rail and pin so Im set. I swap the rails and sears and air it up.

This time it wont shoot. There is just a hair of clearance from the trigger rod to the trigger so that looked fine. The trigger is heavy as if its under pressure. But it wont soot no matter how far I pull the trigger. I take the grips off and try to move the sear with a screwdriver even farther back to see if the trigger rod was just misadjusted but that didnt do anything. I was going to loan the rail and sear out so my buddy could use the gun this weekend but that isnt working. What is going on? I read the manual and it sounded like if the bolt would release but not return then it was a power tube spacer problem. But that isnt whats happening. Any Ideas? Oh and if it helps it is an xvalve with lvl 10 and ULT in a ULE body with an I frame and a classic rail.

I have heard that some bodies are picky on how much tension is put on the screws. Could that be the problem?

The real answer is to have him buy a new sear which Im looking to do for him but incase it happens on a gun of mine in the future what should be done? The sear worked fine with the benchmark frame I had on that rail before. So why now the difference?

[benzy2]

So I swap out his valve for my valve wondering if the problem lies with the body. With my rt valve it runs perfect. So I swap his back in and nothing. I loosen both screws a little and tighten them both a little, nothing. I finally unloosen the rear screw a lot and I hear a click like something dropped and almost like something pressurized and it works great. I tighten the rear screw up a little and it quits working. This cant be right can it? I thought it may be the ULT but I always have pressure on the trigger. It seems like when I tighten things down I lose flow into the dump chamber but there is still pressure on the face of the ult pin giving it a push which is what I feel in the trigger.

EDIT: Also when I hold the trigger down on the x valve and air it up it still shoots a shot as air surges in but then wont fire again. I dont get it. Its like I have no control over the on/off. I cant close it when I pull the trigger to start and I cant seem to get it to open far enough afterwards to fill the dump chamber.

[athomas]

Initially, when you air the marker, the on-off isn't sealing until the pressure builds up. The initial burst of air is causing the bolt to blow forward. A new on-off oring may help a bit here.

It sounds like you are binding the bolt on the body when you put excess torque on the field strip screw. Ideally, you shouldn't be able to do this. Check the length of the pim (nut in the body under the feed neck). If it is hitting the bottom of the hole in the rail, then the body will not properly line up with the valve when you overtighten the field strip screw. The bolt can't go forward if it binds on the body.

[benzy2]

I dont overtighten the rear screw. Take how you would normally screw in the rear screw. And now about 5 -10 rotations before you would stop is where it works. Its not like Im cranking it tight. And after that I honestly dont know what you mean.

[athomas]

I dont overtighten the rear screw. Take how you would normally screw in the rear screw. And now about 5 -10 rotations before you would stop is where it works. Its not like Im cranking it tight. And after that I honestly dont know what you mean.

5- 10 revolutions before you would stop = 5/32" - 5/16" That means the field strip screw would be sticking out quite far.

You don't have to crank it tight to cause binding if the pim is too long. If you tighten the valve, it rocks the body towards the rear and makes it so the valve and body no longer line up in a straight line. The level 10 is so sensitive that any misalignment or side contact on the bolt will cause the bolt to not cycle.