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Air Gun Forums » Air gun Alley » Crosman, Benjamin, Sheridan » Mrod .25 high power valve mod

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Old 04-29-2015, 10:18 PM   #1
Rdsail
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Default Mrod .25 high power valve mod

Note: This mods are OK on Gen1 .25 valve. I would not recommend them on the Gen2 valve. There is less material behind the poppet. For gen 2 valve I would not go past .187 for the exit port.

Throat: .256

Here is the view of the exit port. Mods. tube and breech opening increased to .325. exit port .203
I also made the hammer track longer by just over ⅛ in



I don't know what else I can do to get more power out of the valve. other than removing some material from the valve body so I can gain a little more hammer travel.

I hope this helps and I'm open for any other suggestions. I have not tested this valve so I have no idea of the performance.

Gauge block: opend as much as possible
Hammer. Removed the adjuster screw for more travel. Casted lead in the side openings for 109gram hammer

[IMG][/IMG]

Angled exit port.


Valve intake: center opening .325, side openings .184 I would not open the side openings more than .184. it is important to only do 3 opening in this configuration and placement. The reason is that if not you will drill through the breech screw opening and you will have a mayor air leak.



Inside of the valve bore out to ½ in



Moving parts. PEEK poppet (From Doug - PakProtector), conical spring. and spring holder. I shorten the spring holder by about ¼in. On the valve body you can see the holes for this valve to fit Gen2 trigger



For the transfer port I have two option. Both opened to .203
Top: 2 1mm orings and stainless standoff.
bottom. PTFE tubing cut to size.
I'm going to try the tubing first and see if it seals and there are no leaks.

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Diana 48 .177, AA S400 MPR FT .177 - Field Target - WFTF, Custom Bottle Disco .22 - 30 fpe, Mrod .25 Project gun
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Old 04-30-2015, 03:50 PM   #2
ezman604
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Nice work Daniel!!!
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Old 04-30-2015, 03:56 PM   #3
Rdsail
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Just waiting for my new barrel to test it out.
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Diana 48 .177, AA S400 MPR FT .177 - Field Target - WFTF, Custom Bottle Disco .22 - 30 fpe, Mrod .25 Project gun
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Old 04-30-2015, 06:14 PM   #4
grumpy
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Daniel, ya always do some fantastic work ! By the way welcome Dave.
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Old 04-30-2015, 06:21 PM   #5
critter99
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Quote:
Originally Posted by Rdsail View Post
Just waiting for my new barrel to test it out.
SO Dan what the barrel a TJ liner and caliber??
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Old 05-01-2015, 02:54 PM   #6
Rdsail
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That is correct. a TJ .25
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