pump mag problems

[gsumner21051]

I need some help. I'm building a pump mag. ULE body, x-valve, ULT kit. I was having problems with bolt stick, changed power tube spacers. It helped, but it didn't solve everything. To that point I was using the stock on/off so I installed the ULT kit. Made most of the bolt stick go away after adding all the spacers to it. I've also changed the bolt springs (long-nose bolt) with some improvement.

I don't know what to do, I'm out of ideas. Sometimes the bolt stick and sometimes it doesn't, when it does fire you can hear a noticable difference between shots so I know the chrono speed is all over the place.

[Snake847]

well the pump conversion is supposed to do that.............

[gsumner21051]

sticking back, not letting it fire. just for clarification

[Snake847]

yep
you are supposed to reset the bolt with the pump rod

[gsumner21051]

i reset the bolt with the pump rod by pulling back and releasing the pump handle to let the pumo rod back forward. the on/off charges, and i fire but sometiems the bolt sticks in place and won't fire, all i hear is a hissing. when the gun does fire, it doesn't fire at a velocity that's even remotely consistent. i'm talking +/- 80 fps.

[Dryden]

Remove the barrel and check inside the breech to see if the pump rod is still sticking up in the path of the bolt.

When you put the pump rod into the pump handle, you should hear an audible click. It requires some force. If the pump rod isn't staying down in the rail, the bolt is probably hitting that, restricting airflow out of the power tube tip and causing the random velocities.

[gsumner21051]

the pump rod is definately locked in place. has anyone ever heard of a pump kit just not working with an x-valve? i had a classic valve that i traded for the x-valve and when it was installed i didn't have problems like that.

[Dryden]

OK. After rereading your first post, it sounds as though you've taken the Level 10 out of the X-Valve and replaced with a Level 7? If you remove the wave spring and pump rod, effectively turning it back into a semi auto, does it fire without any issues then?

[gsumner21051]

yes, that's what i did. the level 7 is more air efficient and i'm planning on running a 12 gram...

and i didn't think to try removing the wave spring and firing it in semi mode until you mentioned it. i have just done so to no avail, it's still giving me issues trying to fire. i tried changing power tube spacers again, no such luck.

[Dryden]

and i didn't think to try removing the wave spring and firing it in semi mode until you mentioned it. i have just done so to no avail, it's still giving me issues trying to fire. i tried changing power tube spacers again, no such luck.

Double check that you put the correct spring back on the bolt, the Level 7 spring and not one of the ones from the Level 10 kit. Also, remove the ULT from the equation and go back to the original RT on/off. Remove as many variables from the equation as possible and add them back in one at a time to see where things go wrong. With virtually everything returned to factory stock/semi auto, just see if you can get the Level 7 bolt running reliably. If you get bolt stick, use a hard squeegie or pencil or similar to try pushing the bolt back and listen for a click. Since you've taken out the level 10, be careful to point the marker in a safe direction when doing this, and do not stick your finger in the breech and do this by hand.

I'd also double check that you're using the correct Level 7 powertube o-ring and not one of the orings from the Level 10 kit. You also need the Level 7 powertube tip and appropriate spacer, probably .225. Apply a drop or two of oil to the bolt stem before putting everything back together.

Reintroduce the ULT and tune after everything is working with the Level 7.

Its a royal pain and very tedious, but trying to tune the bolt and a ULT on/off at the same time isn't worth the headaches.