Pump mag troubleshooting

[Smokee_2_7]

I'm having some difficulty working on a pump mag for a friend.
This is my first time working on a pump conversion, but after reading everything I could find on AO and google I realize that it's not that much different.

Here's the setup:

classic valve, ule body, non-agd pump kit.

The first problem was a persistent leak down the barrel, which wouldn't stop even if the trigger was pulled. Checked and replace both the powertube oring and the powertube tip oring: still leaking. I checked the pt spacer---- .215. I noticed that the bolt spring ( normal lvl7 spring) had been cut down. I theorized that the cut spring was not pushing the bolt back far enough to seal on the pt oring. Replaced the bolt spring with a new lvl7 spring. This caused the leak to stop.

Unfortunately, now the marker fires in semi: the pump is for decorative purposes only. I think the stock boot spring is causing the bolt to overcome the tension of the wave spring, allowing the sear to reset.


Any ideas?

Carl

[Ando]

If you have a lvl 10 installed....pull it

RT on/off...pull it

You must cut the rubber bumper so it fits inside the wave spring. The wave spring should fit flush against the body of the valve.

[fishmishin]

Nah he's not running a lvl X

If you have a lvl 7 Pt spacer kit move up to a .225 spacer, and try swapping the spacer and the PT o-ring around. Yeah I know it sounds weird, but it has worked for me and a couple of others. Also go back to the cut spring, that is going to be your best bet. You should try to correct the leak by changing out your PT spacers, and swapping the spacer and the o-ring around. Also like Ando mentioned make sure you have cut the bumper so that it fits inside of the wave spring. hope it helps, pump mags can be tedious to tune, but when they are right the are golden.

[fishmishin]

Also here is the thread where everyone tried to help me out last year, it may help some also.

http://automags.org/forums/showthread.php?t=246750

[pump]

either wave spring is too short or your rail frame spacer is not there so the wave spring isnt hard enough

but the leaking got me stumped

[Smokee_2_7]

Thanks for all the help. I've just finished working night shift the past 2 days and have not had a chance to try anything with the gun just yet. On my way to do some scuba diving right now, will sit down with the pump later this evening.

I'll let you know what I find out!




Carl

[Smokee_2_7]

Ok, I was able to sit down with the gun today, and here's what I found out.

First off, the rail bushing was missing. I installed a new one in the rail, then was suprised to see that the airwalk frame would not take the bushing: the rear hole in the grip frame was to small for a bushing except for a shallow 'counter-sunk' area on the top (where it mates up with the rail). I've not worked with an airwalk frame before, but I assumed that they take some kind of shortened rail bushing.

I replaced the airwalk with a stock 'mag frame and removed the pump components (pump arm, wave spring, cut bumper and cut bolt spring. Gassed it up and there were no problems. I reinstalled the pump components & added air. No leaks, but now the pump stroke wouldn't reset the bolt. I could manually reset the bolt by gently pushing on the bolt face with my finger.

I took it apart again and inspected the pump arm slot in the rail. This was apparently a stock 'mag rail that someone had cut out for the pump arm. I paid particular attention to the 'slope' towards the rear of the slot ( the area that forces the tip of the pump arm up into the mainbody to engage the the bolt). There was some obvious wear on this area. Either that, or the person that cut the groove went back to the slope with a dremel tool. I happen to have an old body rail with a factory- cut pump groove so I compared the two.

I wish I had taken pictures. The slope area on the AGD groove was much steeper (and shorter) resulting in the pump arm rising to engage the bolt sooner in the throw. When comparing the two, the 'after market' groove put the tip of the pump arm BEHIND the bolt instead of in front. This resulted in the 'pump that would not pump'.



So with a factory-cut pump body rail, rail bushing and a frame that would accept that bushing the pump is awesome. Unfortunately for the owner, my old-school rail is not for sale!


Thanks to everyone for the help and suggestions!


Carl

[flyingpootang]

Carl, simple fix by bending the arm a little will cure your problem. If the pump arm drags bend it a little more. A cause of dragging is the arm slipping under the bolt lip.

[tbaggin]

seeing as you mentioned an airwalk frame, this must be my old pump (purple ULE)

the rail and body were both prof milled by Rainman229 on MCB, the pump kit is a cerebrus ( barely used). I tested the gun many times before i shipped it, even used it for a day. Im not sure what the problem could be, but just so your buddy knows, that rail wasnt touched with a dremmel, nor was the body.

[Smokee_2_7]

I turned the marker back over to the owner this afternoon after explaining what I found. I'll make sure he sees this thread so he can try bending the pump arm a little more if he'd like. He told me that he played a day with the gun after receiving it without any problems--- so I'm wondering what happened just like you guys.

As far as the rail goes, I don't doubt that it wasn't done professionally, nor do I insist that it was dremeled. It could be signs of wear from the pump arm on the slope. I wish I had taken a comparison picture with my old rail. The slope is just a little different.


Carl

[inkundone]

If you have a lvl 10 installed....pull it

RT on/off...pull it

You must cut the rubber bumper so it fits inside the wave spring. The wave spring should fit flush against the body of the valve.

not that it means anything at all, my rubber bumper is not cut and my pump mag works flawlessly. Would you recommend still cutting it though? what would cutting it fix?

[pbjunky99]

Yea tbagging it's the one I got from you. I'm not blaming you though. It did great the first day I played with it. After taking a gun shot (I hate gun shoots) I took it apart to clean it and that's when everything went hay-wire. I have now got it pumping again and its goodbto go. Thanks smoky for the work and research you put into it.

[tbaggin]

Glad you got it working and you like it. I always want whoever buys stuff off me to be 100% happy with it.

I wasnt inferring you were blaming me at all, I just didnt want you to think the milling was a hack job, lol.


and I def can see what your buddy was saying, because i too have had an OEM AGD milled rail, and it is def a lil different.


again, glad you like it, it was hard for me to part with as I love Pump mags, but I have a new baby on the way, and am selling alot of stuff.

[Smokee_2_7]

Pbjunky,

Did you tweak the pump arm a little bit as suggested? I was originally thinking that the arm was going behind the bolt rim, but I can see how bending it a little more cold cause it to engage the bolt earlier in the stroke.

[flyingpootang]

The whole idea is to have it high enough to contact the bolt face and still low enough for the bolt not to hit it when the rod is all way forward....