68 Doesn't Fire: No Leaks, Airs Up, Bolt "clicks", pressure behind trigger.

[sup909]

So I replace the regulator piston assembly on my classic 68 since it was so old it couldn't take the LVL 10. Put everything back together, aired up the marker and........Nothing happens when I pull the trigger. The marker is pressurized, the bolt "clicks" into place, I can feel the air pressure behind the trigger, yet when I pull the bolt doesn't go forward. Nothing happens.

Any thoughts?

[michbich]

Raise the velocity. The LVLx takes more air then the LVL 7.

[sup909]

Raise the velocity. The LVLx takes more air then the LVL 7.

Hmm, well that sort of fixed it, however I hard to turn the velocity screw almost literally all the way in. It is not leaking slightly out the back. I just installed a new regulator piston, that can't be it can it?

[michbich]

Hmm, well that sort of fixed it, however I hard to turn the velocity screw almost literally all the way in. It is not leaking slightly out the back. I just installed a new regulator piston, that can't be it can it?

Did you mean that it's leaking from the back? or not? I can't quite make out your sentence. Is your mag running fine now or is there a leak somewhere?

[sup909]

Did you mean that it's leaking from the back? or not? I can't quite make out your sentence. Is your mag running fine now or is there a leak somewhere?

Well I kept turn the velocity screw in and pulling the trigger until it would fire. It started firing about 1 turn from being all the way in. However there is now a slight leak out the back. One problem solved another created. The velocity screw shouldn't have turn go in that much should it?

[michbich]

Do you have LVLX? If so, maybe change the spring for a shorter one. Did you chrono it?

[sup909]

Do you have LVLX? If so, maybe change the spring for a shorter one. Did you chrono it?

Level 10 with a classic valve. I don't have a chrono on me unfortunately. Would a shorter spring have any effect on the air up of the bolt?

[michbich]

Without chronoing it, it's pretty much a shot in the dark. You might be shooting hot without realizing it. Try a shorter spring and see how it goes...that's what i would do.

[garbageman705]

Sounds like your carrier is too tight or your spring is too long.

[code_red]

Loosen your field strip screw.

[athomas]

If you replaced the piston assembly, then you should be fine there. If you had to increase the velocity setting as high as you indicated, then you are probably getting a pressure high enough to cause venting. Pressures this high without firing are usually a result of the bolt sticking. Make sure you are using the largest carrier size that doesn't leak. Remove all the shims when checking the size and always use the same white oring for each carrier size being checked. When doing the squeegie test, hold it tight against the face of the bolt. If you hold it more than 1/4" from the bolt face, you will feel full bolt impact which is higher than the level 10 reduced value.

[sup909]

If you replaced the piston assembly, then you should be fine there. If you had to increase the velocity setting as high as you indicated, then you are probably getting a pressure high enough to cause venting. Pressures this high without firing are usually a result of the bolt sticking. Make sure you are using the largest carrier size that doesn't leak. Remove all the shims when checking the size and always use the same white oring for each carrier size being checked. When doing the squeegie test, hold it tight against the face of the bolt. If you hold it more than 1/4" from the bolt face, you will feel full bolt impact which is higher than the level 10 reduced value.

Thanks for the run down. I think I will begin with the smaller spring. I will see if I can put a few hundred rounds to break in the carrier o-ring to turn the velocity down.