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Thread: Pump mag advice

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  1. #1

    Pump mag advice

    So

    I've been assembling a pump mag and I've been running into issue after issue and looking for any advice tips or tricks for how you got your pump mag to work..

    I have:

    Pump milled ULE body
    Pump milled rail
    Rain man Pump kit
    Reverse minimag valve w/ efficiency insert

    So I started assembling it and ran into the pump sticking, proceeded to dremel a wider groove and solved the issue until I put the body on. Dremel'd some more. Problem solved. Then I realized it was still shooting on semi. Then the pump stroke started to stick again..

    Anyways looking for some advice/help, because I am beyond frustrated and thinking about giving up and parting it out.


    Thanks
    GWH

  2. #2
    Who did your pump milling on the rail and body? What spring are you using, do you have the wave spring in place, worn out?

    Id also say take out the efficiency insert, if I remember right others had issues with it.

  3. #3
    All the milling was done by Luke rail/body..

    I'd prefer not to take out the insert.. I don't believe it can be just taken out?

    Wave spring should be good, how can I tell if its worn out?

  4. #4
    Join Date
    Oct 2004
    Location
    Sebring, Florida
    Posts
    837
    Somewhere )I don't recall where( there's spec's for compressed and relaxed measurements for the wave spring. It's here on AO but I'm not sure where I found it. Worst case I think in the same info thread there was a link to get new waves. Good luck. The death of my pump mag was poor milling but Luke Does the milling right. I got myself a Sterling and then went totally Ape customizing it. I've had lots of fun.
    I took the road least traveled...now where the hell am I ?

  5. #5
    Join Date
    Oct 2006
    Location
    Houston, TX
    Posts
    3,210
    You also need a weak bolt spring, one that sits about even with the tip of the bolt, maybe a little less.

  6. #6
    Join Date
    Jan 2001
    Location
    Cottonwood, Az.
    Posts
    5,834
    Quote Originally Posted by GenaroWasHere View Post
    So I started assembling it and ran into the pump sticking, proceeded to dremel a wider groove and solved the issue.
    If you are using an AGD spec pump rod you should not have to widen the groove. Rod diameter should be 0.110".

  7. #7
    Thanks for all the feedback guys, I'm gonna try out the spring mods first

    Luke, I believe the sticking happens from a loose fitting pump rod.. All the way tightened leaves the angled end facing 'upside down' It seems to wiggle loose then touch the inner sidewall of the groove otherwise your milling fits the rod perfectly..


  8. #8
    Join Date
    Jun 2009
    Location
    Kentucky
    Posts
    4,146
    Your sticking is probably from the tip of your rod getting stuck underneath the bolt or the bolt spring itself. Pull your body off and install your valve with the pump kit in place. Pull the pump back and see where it's hitting

    Should look like so. If it doesn't then you need to bend the tip of the rod up or down to hit the right area.



    Your semi auto problem Is due to your bolt spring doing its job. If you don't have a worn spring, you'll have to cut one down. When cutting though, cut a very small amount at a time. Cut a 1/4 inch off for your first cut then go in smaller increments from there. You want your spring just weak enough that it doesn't auto cock the bolt but have enough pressure on the bolt that all it tales to cock it is a very light pull of the handle. If you have it set right, you should be able to just jerk the marker back and forth real quick to cock it.

    Also put the cut side of the spring towards the bolt not the body.

    Another thing you're probably going to run into is a bolt leak once you have the spring set right. You'll need to go to a smaller spacer if the leak does appear.

    Other then that. You shouldn't have any other issues.

  9. #9
    Quote Originally Posted by Ando View Post
    Your sticking is probably from the tip of your rod getting stuck underneath the bolt or the bolt spring itself. Pull your body off and install your valve with the pump kit in place. Pull the pump back and see where it's hitting

    Should look like so. If it doesn't then you need to bend the tip of the rod up or down to hit the right area.



    Your semi auto problem Is due to your bolt spring doing its job. If you don't have a worn spring, you'll have to cut one down. When cutting though, cut a very small amount at a time. Cut a 1/4 inch off for your first cut then go in smaller increments from there. You want your spring just weak enough that it doesn't auto cock the bolt but have enough pressure on the bolt that all it tales to cock it is a very light pull of the handle. If you have it set right, you should be able to just jerk the marker back and forth real quick to cock it.

    Also put the cut side of the spring towards the bolt not the body.

    Another thing you're probably going to run into is a bolt leak once you have the spring set right. You'll need to go to a smaller spacer if the leak does appear.

    Other then that. You shouldn't have any other issues.
    If you don't mind me asking, in what order does the black bumper fit into the assembly of the bolt/valve?
    Does it sit next to the valve and under the wave spring?

  10. #10
    Join Date
    Sep 2008
    Location
    Sunny Florida- Woot!
    Posts
    4,857
    The bumper is supposed to fit inside the wave spring. It needs to be cut down.

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