Chuff probs on X-valve/ULE body/TAC rail

[rav3nware]

Hey guys,

I replaced my old Micromag body (integrated rail) with a snazzy new ULE centerfeed body and wingless Tac rail recently. Since switching to the new body and rail (which required switching to a new kind of sear assembly) the marker chuffs constantly at anything over 4 or 5 pulls a second If I hold the trigger down lightly, I can hear air venting down the barrel, and when the marker chuffs it feels as though the valve isn't cycling or resetting all the way.

My current setup is:
ULE centerfeed body
X-Valve
Wingless TAC rail (with appropriate sear; I forget which it is, but it's the one with the roller bearing)
Benchmark double-trigger frame
Smart Parts maxflo 4500PSI (output set to around 850-900PSI)

Please note that I chuffed rarely if ever before I changed from the micromag body to the ule body/TAC rail combo, and if I did it was usually from bad trigger technique. Please help!

[nipplez]

try to loosen ball detent on the ule body, if that doesn't work make sure the front frame screw and the field strip screw are about the same torque.

[rav3nware]

I doubt it's the ball detent, I haven't taken it to the field yet and I don't plan to until I get this issue fixed :/ I'm curious though, how would different torques on the two grip screws cause the marker to chuff? I was thinking it might be on-off pin length or something like that...

[fred1]

differnt torques wont alow the body and vavle sit level if there at the same torque there equal (same torque --/ diferent torque -_) i dont know if that little half a** drawing helped but there it is.

.:FRED:.

[MadPSIence]

you could just be shortstroking like a mofo.

[stop whining buy a mag]

I'm pretty sure you need to change your on/off pin. I think the Micromag integrated body/rail is different than the Tac-Rail (RT Pro rail basically). Don't quote me on that though. Look it up in the tolerance section that BlackVCG wrote.

[athomas]

Yes, the micromag boy requires a much shorter on-off pin than the standard body. That being said, the shorter micromag pin should cause full auto issues rather than short stroking/chuffing issues.

If slightly pulling the trigger produces a leak down the barrel, then you need to remove a shim or two from your powertube.

Is the trigger rod properly adjusted for the valve and grip frame that you are using.

[rav3nware]

Yes, the micromag boy requires a much shorter on-off pin than the standard body. That being said, the shorter micromag pin should cause full auto issues rather than short stroking/chuffing issues.

If slightly pulling the trigger produces a leak down the barrel, then you need to remove a shim or two from your powertube.

Is the trigger rod properly adjusted for the valve and grip frame that you are using.

the trigger rod isn't touching the trigger, if that's what you mean. As for the shims, I'll take a look at my Lv10 settings, however I'm still using the same X-Valve and same mainspring as I was before, the only thing that's changed is the mainbody (and the rail with it, obviously).

I was thinking on/off pin too, but what confuses me is that I had no problems when I switched from my old valve to the new X-Valve. I just dropped it in to the body and started shooting. Took me a while to get the Lvl 10 set up right but once I did, it worked fine, and now that I've changed mainbodies it barely even works.

[rav3nware]

Is the trigger rod properly adjusted for the valve and grip frame that you are using.

How do I tell?

[athomas]

The fact that it is actually firing and not touching the back of the trigger usually means the trigger is ok even though it may need to be tweaked for optimum performance. I wouldn't worry about that part. Check that the sear assembly can move freely. Do this with the valve out of the body. Check that the bolt can move freely in the body. Do this with the valve in the body and the bolt installed on the valve without the bolt spring. The bolt should fall forward when the body is held forward. If not, a gentle tap on the back will usually allow it to move. You should be able to move it back into place easily with your finger pushing it from the front. This will tell you if there any sticking spots in the breach. Other than that, its purely valve issues such and on-off or valve pin, etc.

Oh, one more thing to check. Make sure the rear framescrew is the correct length. If it is too long, it may bottom out and cause the valve to not be tight enough in the body.

[rav3nware]

The fact that it is actually firing and not touching the back of the trigger usually means the trigger is ok even though it may need to be tweaked for optimum performance. I wouldn't worry about that part. Check that the sear assembly can move freely. Do this with the valve out of the body. Check that the bolt can move freely in the body. Do this with the valve in the body and the bolt installed on the valve without the bolt spring. The bolt should fall forward when the body is held forward. If not, a gentle tap on the back will usually allow it to move. You should be able to move it back into place easily with your finger pushing it from the front. This will tell you if there any sticking spots in the breach. Other than that, its purely valve issues such and on-off or valve pin, etc.

Oh, one more thing to check. Make sure the rear framescrew is the correct length. If it is too long, it may bottom out and cause the valve to not be tight enough in the body.

Sear freedom was the first thing I checked, it's the roller-bearing sear (I think that's the E-Mag style) and it's not sticking anywhere that I can tell. Pretty sure the bolt isn't sticking either, it feels like a recharge issue in the valve rather than a mechanical stick... hard to describe other than to say that's just the way it "feels" from firing it. The rear frame screw is sized properly as well, the valve tightens down quite well.

One thing to mention - the X-valve doesn't "bottom out" against the back of the ULE body when I screw it down, i.e. where the "mouth" of the mainbody would meet the front edge of the valve body, there is a small gap. Not sure if this would affect things or not.

[athomas]

A gap between the valve and the body is fine. One thing to check though is the presence of the rail bushing in the back. If it is missing in the rail, then the valve will not sit in the proper position.

[rav3nware]

adjusted the trigger rod just to see if it would have any effect... didn't. the rail bushing is there, also. the on/off pin is starting to look like the only thing it could be now, only question is do I need a longer one or a shorter one?

[athomas]

The stock X-valve on-off pin (.750") is the correct one. It is longer than the Micromag on-off pin. Did your Micromag have a proper micromag pin or a stock X-valve pin? If you already had the stock pin then you are good to go.

How old is your X-valve? ie; How many shots have been fired? Have you changed your bolt spring? Maybe its weak.

[rav3nware]

The stock X-valve on-off pin (.750") is the correct one. It is longer than the Micromag on-off pin. Did your Micromag have a proper micromag pin or a stock X-valve pin? If you already had the stock pin then you are good to go.

How old is your X-valve? ie; How many shots have been fired? Have you changed your bolt spring? Maybe its weak.

Sorry for the late reply, I've been on deployment these last few weeks and 'net access has been scarce.

That's the part that confuses me... I replaced the A.I.R. valve my Micro came with with an X-Valve a while ago and it shot fine. I never even touched the pin, just swapped the valves and played with the Lvl10 settings until the marker worked right. When I swapped the micro body for the ULE body and wingless rail recently, the problems started. With the new body/rail, the gun shoots as it should if I pull the trigger slowly, but chuffs every trigger pull at anything around 4 pulls per second or higher That's with the stock X-Valve on-off pin, keep in mind.

Just for simplicity's sake:
Micromag body/integrated rail
X-Valve (stock on-off pin)
Benchmark trigger frame
Proper operation

ULE body/Wingless tac rail
X-Valve (stock on-off pin)
Benchy trigger frame
Constant chuff unless fired very slowly

The different on-off pin tolerances might explain why it took my X a while to break in and shoot properly, though *shrug*

I'll try swapping out the mainsprings when I get home and see what happens. All I have on me are the 3 that came with the X-Valve. If you're saying I might need a stronger spring, that would mean switch to the longer one, right?

Thanks for all the info.