MPP - turning down a 39x valve to fit disco tube

MPP - turning down a 39x valve to fit disco tube

Joined: March 1st, 2002, 12:22 am

May 27th, 2012, 5:30 am #1

the disco tube is of course slotted....

but my question is, does the 39x vavle have enough meat in the walls to make it small enough to fit the tube's ID? and still have the strength to withstand Rob pumping it 20 times?

now it occurs to me, that after turning it down, it should be secured with a couple more screws.........

edit: using the disco tube.... use a disco hammer/striker?


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Last edited by dan_house on May 27th, 2012, 5:41 am, edited 1 time in total.
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Joined: June 25th, 2002, 1:34 pm

May 27th, 2012, 10:21 am #2

n/t
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Joined: April 12th, 2002, 5:26 am

May 27th, 2012, 4:24 pm #3

the disco tube is of course slotted....

but my question is, does the 39x vavle have enough meat in the walls to make it small enough to fit the tube's ID? and still have the strength to withstand Rob pumping it 20 times?

now it occurs to me, that after turning it down, it should be secured with a couple more screws.........

edit: using the disco tube.... use a disco hammer/striker?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
Let the tube do it, and gain a bunch of volume(and performance)

So far as more screws...one thing I've done in the 392 is to open up the tube hole so the shoulder of the take down bolt can be seated against the valve,so the shoulder takes the side load. In a pumper disco I'd do that, and borrow from the 160/QB, by using an internal collar behind the valve, with the receiver hold down bolt into that.
Last edited by classicalgas on May 28th, 2012, 5:38 am, edited 1 time in total.
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Joined: April 1st, 2009, 3:18 am

May 27th, 2012, 7:04 pm #4

That's what I was gonna say. The Disco tube has no stamping present to stop the valve. A shft collar will suffice as long as it isn't too thick. If too thick, it will act as a hammer regulator on the valve limiting the amount of travel in which the hammer can strike the pin. As it turns out, on a little custom pistol I built, used that exact same method. The collar acted as both the breech securing method AND allowed the gun to produce two mid 500fps shots on 10 pumps.

This pistol:


"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: April 28th, 2010, 12:23 am

May 27th, 2012, 10:38 pm #5

Last edited by robnewyork on May 27th, 2012, 10:40 pm, edited 1 time in total.
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Joined: April 28th, 2010, 12:23 am

May 27th, 2012, 10:42 pm #6

the disco tube is of course slotted....

but my question is, does the 39x vavle have enough meat in the walls to make it small enough to fit the tube's ID? and still have the strength to withstand Rob pumping it 20 times?

now it occurs to me, that after turning it down, it should be secured with a couple more screws.........

edit: using the disco tube.... use a disco hammer/striker?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: April 1st, 2009, 3:18 am

May 28th, 2012, 12:06 am #7

...is to create a larger bore pump tube pumper, like the Benji line of guns, but with the ability to choose caliber, breech, etc., as using the Discovery tube will allow such. A Benji made of steel essentially. With that, the provided Benji stroke of 7-5/8" is a good starting point to experiment with valve volumes.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: March 1st, 2002, 12:22 am

May 28th, 2012, 2:16 am #8

SO after working the kinks out..... find some stainless of the same dimensions, and have it drilled and slooted as a side pumper


But... what do you mean "let the tube do it"?

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Joined: April 12th, 2002, 5:26 am

May 28th, 2012, 5:36 am #9

with the two o-rings and the turned down and slotted section,you about double the storage volume, by using the tube as the outer skin of the valve.
Last edited by classicalgas on May 28th, 2012, 5:37 am, edited 1 time in total.
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Joined: March 1st, 2002, 12:22 am

May 29th, 2012, 4:00 am #10

ok, when i get him, parts will be ordered!

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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