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Thread: New RVA for my AR

  1. #11
    Senior Member Doc Sharptail's Avatar
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    I'm kind of curious about what's been done to the valve on this rifle? Since my next build is going to be .177
    If it's been posted elsewhere, I've been unable to find it.

    Thanks in advance

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  2. #12
    Senior Member sholo's Avatar
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    Quote Originally Posted by Doc Sharptail View Post
    I'm kind of curious about what's been done to the valve on this rifle? Since my next build is going to be .177
    If it's been posted elsewhere, I've been unable to find it.

    Thanks in advance

    Doc Sharptail
    I never did mention what was done to the valve Doc, so yeah...it would be hard to find! My bad...

    All I did was take the filter screen, piercing pin, spacer bushing (or whatever it's called) and washer out...basically everything but the valve stem. This resulted in the stock valve spring too short, so installed one that was the correct length and "about" the same strength.

    I also opened up both sides of the valve front to allow more air into valve. Not near as much as Bob did on his '78 though. No pics of it, but all I did was drill a 5/16" hole on each side in line with valve poppet, then cut a 1/4" slot with the Dremel from hole to end of valve. Deburred the rough edges and reassembled.

    Once it was back together, I had valve in my hand pushing on the valve stem checking out the spring action under compression and noticed that the spring was "skating" across the face of poppet. On one compression cycle the spring would stay nice and straight, the next it would be pushed off to the side a bit (making spring "arc" rather than compress properly), then the next one could be pushed to the opposite side. Didn't like that idea much, so I took valve apart, put valve stem in drill press and made a spring seat using the edge of a file lightly pressed against poppet until it just fit in spring:
    m_AR valve spring seat 002.jpg

    Again,no pics, but made a spring guide on valve front by drilling/tapping the hole where piercing pin would normally be to 1/4"x28, then installed a piece of 1/4" bolt (1/2" long IIRC), which I drilled out to 9/64" to allow air to flow through into valve. Removed all threads on bolt guide except for the portion that was actually threaded on valve front (about 3-4 threads). Put a dab of red Loctite on threads and installed it, being sure it sat flush with the bottom of slot in valve front so I could still use my flat bar to tighten/loosen valve. BTW - still using the stock valve stem running HPA @ 1500 psi for a year now with no problems at all (not yet, anyways). I periodically run some shots over the chrony just to check for consistency, and it has been spot-on so far...

    Hope my description made sense to you! Next time I have gun apart I will take some pics to show what I've done...


    Cheers,
    Todd
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  3. #13
    Senior Member SeanMP's Avatar
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    I'm pretty sure the valve in Todd's FT gun in bone stock other than the milled pocket for the transfer port.

    But...He's due at my place in a couple hours so we can find out.

    I know on my .177 with a stock valve I had to back off the spring substantially and put in a .058 port restrictor to keep it in the 550-575 I wanted for a 10m rifle.
    Sean

  4. #14
    Senior Member Doc Sharptail's Avatar
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    Quote Originally Posted by sholo View Post

    Hope my description made sense to you! Next time I have gun apart I will take some pics to show what I've done...


    Cheers,
    Todd
    Makes perfect sense to me. I completely understand what's happening with that valve stem spring.

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

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