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Thread: Chambering a Panda

  1. #1
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    Chambering a Panda

    Getting ready to chamber a new Krieger in 22BR for my new to me Panda. The instructions on Kelby's site state the following "When chambering for a Panda, Kodiak or Grizzly barrel cut the tenon 1.0625 in diameter by 1.115 for a cone bolt action or 0.980 for a flat bolt action. For an Atlas barrel cut the tenon 1.0625 in diameter by 0.692 for a cone bolt action or 0.557 for a flat bolt action. It is recommended that the first 0.110 from the rear of the barrel be turned to 0.966 diameter. Leave the rear end of the barrel square for now."
    What's the purpose of turning .110" down to 0.996"? Is that a thread relief up at the barrel shoulder, or a relief at the end of the barrel for some reason? It's not clear to me, obviously.

  2. #2
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    They are talking about at the start of the thread next to the cone not at the shoulder end of the thread. This gives a little neater appearing start of the thread than just having it start at the end of the tenon. If you cut a thread relief at the barrel shoulder then .966" would be way more than necessary as the minor diameter of a 1 1/16" diameter thread is a few thousandths over 1" in diameter. I've threaded barrels with a relief there or without it. It doesn't make much difference one way or the other.

  3. #3
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    I prefer a nice bevel.

    That .966 is the double depth of a 18 tpi 60 degree V Thread.

    By the way, I feel safe in saying that most Gunsmiths turn that tenon to 1.057/1.058.

  4. #4
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    Thank you gentlemen, that works for me. I was a bit surprised at the recommendation for the tenon to be the full 1.0625, I usually go 5-6 thou less than "nominal". Could the action thread be a bit oversize on purpose so it will accept that "larger" major dia? I haven't pulled the current barrel yet, so it will be interesting to see how it was done.

  5. #5
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    Quote Originally Posted by jackie schmidt View Post
    I prefer a nice bevel.

    That .966 is the double depth of a 18 tpi 60 degree V Thread.

    By the way, I feel safe in saying that most Gunsmiths turn that tenon to 1.057/1.058.

    I don't call myself a Gunsmith, but I do cut my tenon at approx. 1.058.

  6. #6
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    Quote Originally Posted by Butch Lambert View Post
    I don't call myself a Gunsmith, but I do cut my tenon at approx. 1.058.
    Neither am I, Butch

  7. #7
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    Being a rookie I trusted the published tenon dimensions. When I re-barreled my brother's 30 BR, he provided the tenon print from the manufacturer. Using the jigs loaned to me by this guy Butch, who does not claim to be a gunsmith, took measurements of the tenon and headspace off the old barrel. Noted the difference in the pitch diameters, the old barrel measured 1.016, whereas the print called for 1.023 - 1.024. The old barrel was chambered by the action manufacturer, I thought maybe he just purposely cut the PD that much smaller, so I went with the published print, hoping it will be a nice fit. Got the tenon done, no go, the barrel did not screw in.

    Back to the phone with Butch, he suggested duplicate the old barrel
    The barrel went back to the lathe, indicated it and chased the thread, cut the thread to 1.016 PD, life was good.

    Question. To what PD do you guys cut the threads on 1 1/16 x 18?

    Why the discrepancy in the published PD and actual to where the action would not even screw in with the published PD?
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  8. #8
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    Nez, pitch diameter is the theoretical diameter of the V's 1/2 way between the major and minor diameter.

    http://www.boltscience.com/pages/screw3.htm

    http://www.boltscience.com/pages/screw3.htm

  9. #9
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    Jackie,

    Thank you.

    I was just curious, not being able to test fit the receiver to the tenon, I relied on my PD micrometer with the proper tips for the pitch to establish the proper dimension for the action to screw on. Remember this the first bolt gun I ever chambered, I thought I was doing the right thing by using the micrometer. The education continuous.

  10. #10
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    Quote Originally Posted by NezRongero View Post
    Being a rookie I trusted the published tenon dimensions. When I re-barreled my brother's 30 BR, he provided the tenon print from the manufacturer. Using the jigs loaned to me by this guy Butch, who does not claim to be a gunsmith, took measurements of the tenon and headspace off the old barrel. Noted the difference in the pitch diameters, the old barrel measured 1.016, whereas the print called for 1.023 - 1.024. The old barrel was chambered by the action manufacturer, I thought maybe he just purposely cut the PD that much smaller, so I went with the published print, hoping it will be a nice fit. Got the tenon done, no go, the barrel did not screw in.

    Back to the phone with Butch, he suggested duplicate the old barrel
    The barrel went back to the lathe, indicated it and chased the thread, cut the thread to 1.016 PD, life was good.

    Question. To what PD do you guys cut the threads on 1 1/16 x 18?

    Why the discrepancy in the published PD and actual to where the action would not even screw in with the published PD?
    Curious, what type of cutter and do you feed the cutter straight in or with the compound. If with the compound, what's it set on? Has the cutter ever been sharpened?

  11. #11
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    Maybe you just got

    a small one.

    I do alot of panda's for different guys and have bbl specs for each. I looked through my computer files and the smallest PD I show is 1.021 Thats looking at 15 different actions.

    I know my pitch mic is right on. I have them qualified with certs every other year.

    Over the years of doing various brands of actions (BR actions) they will vary quite alot. It's just a crap shoot on the first bbl. I've seen undersized, oversized, even tapered. I have one on file that the PD is 1.023 at the action face and tapers to 1.014 at the back! The actions shoots great but it's just one of those things you don't find until you try spinning the bbl on.
    Another good reason to keep good notes!!

    Bbl threading aids sometimes work and sometimes not. Learned that along time ago. Had one action maker tell me" if our bbl threading aid screws on it will fit any action we make of that type" Found out that wasn't true.
    Don't you just love pulling a bbl out of the lathe and it won't fit!

    Richard Brensing

  12. #12
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    Quote Originally Posted by Richard View Post
    a small one.

    I do alot of panda's for different guys and have bbl specs for each. I looked through my computer files and the smallest PD I show is 1.021 Thats looking at 15 different actions.

    I know my pitch mic is right on. I have them qualified with certs every other year.

    Over the years of doing various brands of actions (BR actions) they will vary quite alot. It's just a crap shoot on the first bbl. I've seen undersized, oversized, even tapered. I have one on file that the PD is 1.023 at the action face and tapers to 1.014 at the back! The actions shoots great but it's just one of those things you don't find until you try spinning the bbl on.
    Another good reason to keep good notes!!

    Bbl threading aids sometimes work and sometimes not. Learned that along time ago. Had one action maker tell me" if our bbl threading aid screws on it will fit any action we make of that type" Found out that wasn't true.
    Don't you just love pulling a bbl out of the lathe and it won't fit!

    Richard Brensing
    Richard, I have a Stiller Diamond Back, 1.0625 18 tpi tenon, which is a direct match to a Panda. But a barrel fit for it or a Panda will not fit into the 1.0625 18tpi Bat Neuvo I just installed a barrel on.

    The biggest variations I experience with Actions was the early Farleys. Their "1 1/16 16 tpi tenon" was sort of a "suggestion".

  13. #13
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    I have a couple Pandas and bought a Borden with the spacer to be able to test barrels
    The 1.060 I had been using for the pandas was to tight for the Borden
    I've started making them all 1.057

  14. #14
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    Jackie, that's what I

    have seen also. It seems Bat is a shade tighter than most.

    Richard

  15. #15
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    I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
    Joe Hynes

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