Classic Chuff/PumpMag Problem

[LinearGoose]

Well I just recently put together a Mini-Tac Pumpmag and am having trouble with either the bolt sticking/(moving forward just a tad) and creating a chuff like sound like I am short stroking it or it leaks out of the barrel. I also notice that when I cock it the leaking stops but will sometimes continue after every other stroke as well as my gas milage is not so high. It is in and around 6 balls or so off a 12g.

Things that I have done:
Shot it in Semi- Seemed to work fine without any problems and got 21 shots off a 12g
Replaced the Reg. Seat and turned up the Velocity a bit
Replaced the Main Spring
Checked the powertube oring/spacer (only have one and its a .215)
Oiled it up

Any suggestions would be appreciated, thanks.

[captian pinky]

what valve? what bolt? what on/off?

[LinearGoose]

Oh yeah that would help...

Classic Valve
Level 7
Classic On/Off and pin

[captian pinky]

is your gun chronoed? what is ur full setup?where is ur 12g changer?

[LinearGoose]

Naw none available right now, backbottle adaptor with a Micro CA II

[Spider-TW]

A shorter power tube spacer would be nice to try. Don't have an old style power tube spring by any chance?

Make sure your field strip screw stays snug while you play. My son's pump mag would get very squirrel-ly after playing a while. I finally noticed I had given him my old screw that didn't have a washer on it to keep it from coming loose, and he never checked it while playing. We corrected both.

[flyingpootang]

Have you looked at your trigger rod length? Just be sure to have a credit card size gap when aired up...

[LinearGoose]

I switched the spacer with a spring and then reversed the order I put them in. Powertube oring on top and the spring on the bottom. I also checked that there was a credit card size gap in between the trigger and the trigger rod while the marker was pressurized. After filling it up with air again the gun allowed me to pump and shoot it when it wasn't double shooting(two shots with one click of the trigger), or the bolt getting stuck in a forward position. Also after I shot and waited a few seconds it would start leaking. This persisted until I had to cock it to keep it from leaking every time I shot it.

[athomas]

The oring goes in first, then the spring/spacer. Make sure you aren't missing the rail bushing.

[BigEvil]

Hey Goose, try a .220 spacer instead of the spring. If you have an assortment of those pt springs, line them up and use the tallest one.

[LinearGoose]

So i switched the order of the powertube oring and spring again back to stock. Oring first spring second. The mag keeps on leaking every time I shoot it now and wont stop until I re-cock it for the next shot. Also BigE I dont have any power tube spacers. Maybe I should buy a kit...

[athomas]

It doesn't sound like a powertube related leak. Does it leak when you hold the trigger in? You never mentioned if the rail bushing was in place.

[BigEvil]

It doesn't sound like a powertube related leak. Does it leak when you hold the trigger in? You never mentioned if the rail bushing was in place.

^
^^
^

What he said.

[Ando]

Follow this how too link.

http://www.pentestone.com/paintball/MagPump.html

Make sure you have everything setup correctly.

Someone had this same issue a few months ago and I believe it was due to how he had his bumper and wave spring setup. He didn't cut the bumper.

[LinearGoose]

The rail bushing is in place, and it does not leak when I hold the trigger. I got the bumper cut and inside the wave spring as well.

[athomas]

That eliminates the on-off area. Replace the powertube oring. If you don't have one, swap it with the one around the bottom of the on-off assembly.

[LinearGoose]

I made the swap but it still leaked every time I lift off the trigger or the gun wasnt cocked. I think I am going to get some spacers and a rebuild kit for the valve.

[athomas]

Is your sear worn at the tip where it holds the bolt?

[LinearGoose]

Now for an updated,
I installed a new reg seat again, seems like the one I had went bad, pt oring, on/off oring and also a .220 spacer. It has a new main spring as well. Gun works perfectly in mech mode, but when I install the pump kit it seems to still be capable of shooting without me stroking it. Not saying it doesn't try to resist the urge to not shoot, and provide me with some chuffs, but it still allows the bolt to blow forward on occasion without me having stroking it before each shot. It shoots the best when I pump it, but I can also get away with squeezing the trigger again to make it go off which is defeating the purpose of the pump. No leaks anymore, just the gun being able to shoot when it is not suppose to. I'm thinking it is the wave spring that is giving me the trouble. I also have the bumper cut to fit inside the wave spring like the link Ando posted.

[Smoothice]

You either need a week main spring (old) or cut your new one. The spring is too strong and is over powering the wavespring.

[Ando]

One of 2 things. It's either a warn wave spring or your bolt spring is doing it's job. It's best to use a worn bolt spring with a pump mag. Use your old spring you had in before. If it's still doing it you might have a worn wave spring. You could also try using a full bumper instead of a cut one but the pump stroke might be a little hard so you might be looking at getting a new wave spring if all else fails.

[LinearGoose]

Installed an older and shorter main spring, works perfectly now. God I love mags... Thanks guys for the tech support. Any idea on where I can get some more wave springs for future reference?

[Ando]

Talk with Rainman over on MCB.
http://www.mcarterbrown.com/forums/members/rainman229.html

[LinearGoose]

Sweet I'll give him a holler pretty soon.

Now for a picture of the finish product:
http://img31.imageshack.us/img31/7448/img0428wj.jpg
Cant stop showing it off