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Thread: New Build

  1. #1
    Senior Member Doc Sharptail's Avatar
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    New Build

    Finally got it together, and did a bit of a trial at the gravel pit today.
    I guess pix first...



    There it is in it's entirety. Discovery based 3K custom tube by Derek Vinyard.
    It's in .177...



    One of the most important components to go into a Crosman based build. It's a 1701-P/p-rod grip frame and trigger group. Trigger is a compound lever system, and a huge improvement over the old XX based triggers. This one is set to break at 2.5 lbs, 2 stage, like an icicle. Much improved shooting control.

    There's also a Crosman Challenger RVA on the rifle.



    Not bad for a first trial. This shot was with the RVA in as far as it would go, and about 2400 psi in the tube. I'm much impressed with this performance, especially with a "hurry-up" home made hammer. Hammer spring is a standard discovery spring, and the valve is completely stock. I've changed nothing in it yet. Crosman Premier 10.5 gr ultra mag domes...

    Scope is one of my old stand-by Banner 6-24X 42mm A/O's.

    Just as a point of general interest, with the RVA knob completely out, and 2550 psi in the tube, 133 fps

    Today's test was more functionality than anything else. It fires and holds air, and there's no leaks during the firing cycle, despite no front breech screw in the gun. The 22-XX bbl band is enough for air-tightness, surprisingly.

    Very cold and windy today. I didn't try to log strings, or even get the scope zeroed, and I'm happier that the proverbial pig right now!

    Big thanks to both Eric at http://scopesandammo.com for parts supply, and Derek for the tube.

    I got a bit of work ahead of me getting this rifle to it's potential, and there's going to be quite a bit more on this in the future.

    Regards,

    Doc Sharptail
    Last edited by Doc Sharptail; Mar 28 2015 at 09:31 PM.
    "Ain't No Half Way"

    -S.R.V.

  2. #2
    Administrator AirGunEric's Avatar
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    That's pretty nifty- can't wait to hear more!

  3. #3
    Senior Member Doc Sharptail's Avatar
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    A couple of pix of that way cool trigger:



    There's the 1701-P/P-rod trigger in the cocked position-sear engaged.



    And the same trigger group in the fired position- sear released.

    Turns out I got very lucky with this build- I ran the gun up to 2600 psi with the stock disco screws retaining the valve. Said screws are only rated for 2000psi...
    Looks like my solution will be to go to 10x32x 3/8" high tensile round heads if I want to run the gun at it's max rating. I'll have to drill out and re-tap the holes in the valve. Previous experience says that the balanced threshold usually appears 2 or 300 psi below max. Flat strings are the objective for now- I can deal with power later.
    Thanks to Bob Sterne for the info on the h.i.s. screws...

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  4. #4
    Senior Member remtom1200's Avatar
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    I just received a p-rod trigger block for my 2240 as well. Its the best thing since Tim Horton's...what a difference!
    For every mile of road, there's two miles of ditch

  5. #5
    Senior Member Doc Sharptail's Avatar
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    Long time no see, there RemTom!

    I've done quite a bit with this build since.
    I made a new hammer for it out of stainless, and made a transfer port for it out of disposable lighter parts. I used the flame adjuster collar out of a Tokai brand lighter. All I had to do was drill it out, and cut it for height. Couldn't seem to get the factory T/P to stop blowing air, no matter what I did. If this one blows, I'll go to ice-maker poly tubing. It's held up for 500-600 shots so far.
    FINALLY got some proper h.i.s. low head socket cap screws for it for valve retention at 3 K. Big thanks to Sholo for his help there.

    Performance has improved a lot with the new hammer and transfer port. With the adjuster in to max, I'm seeing mid to upper 9's with the 10.5 gr Crosman Ultra Magnum, and a 2.5 K fill.

    I'd still like to get in a P-rod gauge block for it- the flow hole hole on the disco gauge block is pretty darn tiny

    There's a lot of potential here for an *ahem* medium caliber build... but not right away, yet. More testing and playing around to do ...

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

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