Pump minimag cocking issue

[ghost flanker]

A very brief burp/pop sound emits from the power tube every time the cocking rod resets the bolt. The gun shoots and functions just fine aside from the burping sound, but it's starting to get on my nerves as it takes away from the much more satisfying "click" I used to get.

The powertube assembly is level 7. It has the stock foamy-less bolt and solid brass spacer instead of the spring spacer. I tried swapping out the entire powertube assembly, including the bolt and spring, from two other level 7 guns, both of which had the spring spacer. On both attempts, the problem worsened significantly, with a much louder "psst" sound and noticeable air movement coming out the barrel upon each time the gun was cocked. The original assembly was therefore re-installed.

Next, I tried swapping out the standard on/off assembly with an RT on/off. This made no difference. I'm stumped at this point.

The sear is in good shape. The trigger rod is properly adjusted. The gun is oiled. I'm using a full tank of compressed air. The wave spring is still fresh. Aside from the pump milling, everything on this gun is stock MM parts. I'm stumped.

[captian pinky]

have you tried changing carrier sizes.

[RiverSJ422]

Have you completely rebuild the whole gun?


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[Spider-TW]

have you tried changing carrier sizes.

spacers?

I would try a power tube spacer kit. I never tried a pump mag with the old power tube spring. Pump mags are sensitive to that position, so I would avoid the old spring for that. I never had trouble with them in a regular mag, but after all they (the PT springs) are there to move.

[captian pinky]

spacers?

I would try a power tube spacer kit. I never tried a pump mag with the old power tube spring. Pump mags are sensitive to that position, so I would avoid the old spring for that. I never had trouble with them in a regular mag, but after all they are there to move.

ya thats what i ment.

[Spider-TW]

ya thats what i ment.

That happens when you are fluent in both level 7 and level 10 languages.

[captian pinky]

and doesn't help i run level 10's in my pump mags.

[Nobody]

and doesn't help i run level 10's in my pump mags.

Unless you have them convertable from pump to semi, its utterly pointless. Like using a Xvalve for a pumpmag.

[Nobody]

Powertube oring, but check the bolt itself. You might have gotten a bit of gunk or heaven forbid, a nick on the bolt where it meets the inner powertube.

[captian pinky]

Unless you have them convertable from pump to semi, its utterly pointless. Like using a Xvalve for a pumpmag.

It isn't pointless. It is softer on paint than a foamie level 7 and when im shooting quicker i dont have to worry about chopping with a 50 rnd hopper.

[ghost flanker]

I just now went through another tank and a half troubleshooting and repeatedly rebuilding the gun and swapping out every little part back and forth over and over again. The problem is intermittent with some parts and constant with other parts, but it looks like I'm able to completely eliminate the popping noise only when using;
- a particular on/off pin of the 3 that I have
- a particular on/off bottom of the 3 that I have
- any valve as long as it's not the MM valve I originally had on the gun to begin with
- and the one brass spacer I have (220)...it hates spring spacers
This is the combination that this pump kit wants. Simply nothing else will do. So bizarre. I've never seen a mag be such a picky little bich. But if I take out the wave spring, it shoots as a semi just fine for the most part. I don't understand it. Maybe it really does need a different size spacer, because that's really the only thing I haven't changed out 50 times.