397 converted to SSP

397 converted to SSP

Joined: December 14th, 2010, 5:08 am

January 27th, 2012, 7:28 am #1

just curious... has anybody every converted a 397 into a single stroke pneumatic? i was thinking of how to do it and you could shorten the valve and add a longer piston, drill a new hole in the tube for the intake.. or just shorten the hole gun entirely. when i think about it it seems like it might make kindof a cool little carbine with extra points for being shiny brass
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Joined: April 28th, 2010, 12:23 am

January 27th, 2012, 3:19 pm #2

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Joined: April 1st, 2009, 3:18 am

January 27th, 2012, 3:20 pm #3

just curious... has anybody every converted a 397 into a single stroke pneumatic? i was thinking of how to do it and you could shorten the valve and add a longer piston, drill a new hole in the tube for the intake.. or just shorten the hole gun entirely. when i think about it it seems like it might make kindof a cool little carbine with extra points for being shiny brass
The proper angle to take on the project is to put the mounting holes for the end plug and lever further back. Then shorten the valve.

To make it right (1500psi or higher), the valve would have to be shortened enough to where the swept volume from one stroke is in the needed theorectical range. This conversion would entirely do away with 90% of the valve, i.e. the front half where the check valve is housed and great deal of the rear. A new o-ring gland needs to be cut in what is reamaining of the rear valve section. The valve seal spring will need to be installed on the rear of valve held on with a clip.

I just need to get a used 397 to do it...



"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: November 28th, 2002, 6:26 pm

January 27th, 2012, 4:08 pm #4

just curious... has anybody every converted a 397 into a single stroke pneumatic? i was thinking of how to do it and you could shorten the valve and add a longer piston, drill a new hole in the tube for the intake.. or just shorten the hole gun entirely. when i think about it it seems like it might make kindof a cool little carbine with extra points for being shiny brass
...you'll get far more power if you simply tune an air-conserving 397 for one-stroke recharge than would ever be possible from a pure dump-valve SSP.



Steve
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Joined: April 1st, 2009, 3:18 am

January 27th, 2012, 4:39 pm #5

...I will make a wager with you!

Okay, I will make a true SSP from the 397, as explained, tha will be able to produce the green line velocity figures on your chart. One pump, one shot.

It's on Steve! You are going down, man!!

Gonna put this ACP397 of yours to bed!!

Joking aside, it is possible to get decent numbers in .177 cal with the Benji platform. Could even create a piston (like the Paradigm) that extends a little from spring pressure once the valve is opened. Doubt it would even contribute much.

"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

January 27th, 2012, 5:13 pm #6

just curious... has anybody every converted a 397 into a single stroke pneumatic? i was thinking of how to do it and you could shorten the valve and add a longer piston, drill a new hole in the tube for the intake.. or just shorten the hole gun entirely. when i think about it it seems like it might make kindof a cool little carbine with extra points for being shiny brass
As a member of the Air Conservationists, ( <img alt="happy.gif" src="/images/happy.gif" width="14" height="14"> )I'll watch this closely.

 


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Last edited by dan_house on January 27th, 2012, 5:13 pm, edited 1 time in total.
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Joined: November 28th, 2002, 6:26 pm

January 27th, 2012, 5:26 pm #7

...I will make a wager with you!

Okay, I will make a true SSP from the 397, as explained, tha will be able to produce the green line velocity figures on your chart. One pump, one shot.

It's on Steve! You are going down, man!!

Gonna put this ACP397 of yours to bed!!

Joking aside, it is possible to get decent numbers in .177 cal with the Benji platform. Could even create a piston (like the Paradigm) that extends a little from spring pressure once the valve is opened. Doubt it would even contribute much.

"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."
...might just be the perfect way to make me eat my hasty words.





Steve
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Joined: September 25th, 2006, 2:19 pm

January 27th, 2012, 7:46 pm #8

because the sprung piston re: the Paradigm is in no way the Paradigm's secret. That gun has a much more sophisticated valving design to reduce pressure charge pressure drop than one could ever achieve in the 392 design.

Imagine the minute charge volume required to produce a meaningful shot with a SSP Benji. Then consider the headspace volume from exhaust valve to pellet of the Benji which would be almost equal to the requisite charge volume.
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Joined: March 1st, 2002, 12:22 am

January 27th, 2012, 8:56 pm #9

that the air path is of such volume that the SSP "charge" is not suffiient to fill it, let alone provide neough power to drive the pellet?

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: September 25th, 2006, 2:19 pm

January 27th, 2012, 11:25 pm #10

Yes nt
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