[Solved] Double firing after x-valve rebuild

[ideinit]

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My mag setup:
- LV 10 (no shims)
- x-valve
- ULT (4 shims, pin is 0.75")
- Stock powerfeed body custom welded to vertical feed
- classic rail
- Powerlyte Powerstix frame
- Trigger rod about a credit card thickness from trigger back

I had problems with massive leakage and it was solved with help of many AO members. (Thanks guys! )

But after I test fired 100 or so shot the mag started to double fire - once on trigger pull and once on release. The only things I have done were the valve work to stop the leaks in this post. The sear is not worn up (it was working before) and the bolt lip looked okay.

Could the valve rebuilt have something to do with this? Or perhaps I need to change the o-rings in the ULT as well (or rebuilt)?


Thanks!


EDIT: I've inspected the ULT and all the o-rings are intact, the pin is 0.75" as spec and it has 4 shims.

EDIT: Resolved (see reply #11). It turns out the shims were a mix of ULT and LV 10's - replaced with all ULT shims and it's running smoothly.


X-valve parts list so we can discuss using part numbers:

[ventturei26]

i also have a xvalve that autoresponses by itself...have yet to figure out whats wrong haha. the fun part is where you ignore it and it autoresponse rt's...thats really fun

[ideinit]

i also have a xvalve that autoresponses by itself...have yet to figure out whats wrong haha. the fun part is where you ignore it and it autoresponse rt's...thats really fun

I wouldn't mind if it is RT'ing properly. However many of the times the second shot seems not properly charged and paintballs barely shoot out of the barrel, which is very annoying...

[ghost flanker]

If it's a real auto response where it fires only once when you pull and hold the trigger, then fires again upon releasing the trigger (as opposed to a 2 shot burst) and your sear and bolt are not worn, then it sounds like something is going on with with your on/off assembly. For whatever reason, the on/off is allowing the valve to recharge again before the sear can catch the bolt. Inspect your on/off pin for wear or damage on the tip where it hits the sear - sometimes the tips can actually break off, effectively shortening the pin. Extreme cases can cause runaway full auto.

By the way, how many shims do you have in your ult assembly? Also, what kind of body is that on your gun?

[Tunaman]

What frame is that? Try putting the stock frame back on and see if it goes away.

[Nobody]

Looks like a Powerstix frame

[ideinit]

If it's a real auto response where it fires only once when you pull and hold the trigger, then fires again upon releasing the trigger (as opposed to a 2 shot burst) and your sear and bolt are not worn, [...]

Yes it's doing auto response - one shot on pull and one shot on release.

Inspect your on/off pin for wear or damage on the tip where it hits the sear - sometimes the tips can actually break off, effectively shortening the pin. Extreme cases can case runaway full auto.

I have inspected and measured the on/off pin, it's correct at 0.75" inches.

By the way, how many shims do you have in your ult assembly? Also, what kind of body is that on your gun?

I currently have 4 shims in there. The marker was bought used years ago and I have never messed around with the ULT so I don't know if that is "correct" number.

The body is custom welded stock power feed AM body into a vertical feed.

[ideinit]

What frame is that? Try putting the stock frame back on and see if it goes away.

It is a Powerlyte Powerstix frame. Unfortunately I do not have another frame to test with. However the marker was performing correctly before the valve rebuilt which indicated I've messed something up during the rebuild - I just am not sure what I broke.

[athomas]

Take out one or two shims from the ULT. It will prevent the on-off from opening too soon and causing the chamber to charge before the sear can catch the bolt.

[ghost flanker]

Take out one or two shims from the ULT. It will prevent the on-off from opening too soon and causing the chamber to charge before the sear can catch the bolt.

Took the words right out of my mouth.

[ideinit]

Thanks everyone, especially to athomas and ghost flanker, the issue had been resolved. It turns out the previous owner had mixed up LV 10 and ULT shims - of the 4 shims in the ULT 2 were LV 10 and 2 were ULT. (Still doesn't explain why it used to work properly, albeit a little sensitive.) I now have all 4 ULT shims in it and it's firing properly.

Also now that I know I can modify the reactivity in the trigger, I will be tweaking with the shims and show the electric marker kids some old school action

[ghost flanker]

Lol. I've always wanted an auto response trigger, myself. Never knew I had one all along :)

I wonder if the velocity stays consistent in the trigger release shot.

[athomas]

I wonder if the velocity stays consistent in the trigger release shot.

No, the chamber can't charge fast enough. The bolt pushes forward as soon as there is enough force on the bolt stem to move it, which is less pressure than the velocity setting. Sometimes the surge of pressure causes just a bump on the back of the bolt which is enough to vent air and plop a ball out, but not enough to actually fire a ball.

[SummaryJudgement]

Thanks everyone, especially to athomas and ghost flanker, the issue had been resolved. It turns out the previous owner had mixed up LV 10 and ULT shims - of the 4 shims in the ULT 2 were LV 10 and 2 were ULT. (Still doesn't explain why it used to work properly, albeit a little sensitive.) I now have all 4 ULT shims in it and it's firing properly.

Also now that I know I can modify the reactivity in the trigger, I will be tweaking with the shims and show the electric marker kids some old school action

Hmmmm, I don't think I ever even considered that the shims could be different. Good to know!

[ideinit]

Hmmmm, I don't think I ever even considered that the shims could be different. Good to know!

Yes, the difference in thickness is 0.01" (carrier) vs 0.005" (ULT). You have to put them flat on a table and look from the side to tell the difference...