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Thread: Pre-Drill & Boring A Chamber

  1. #46
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    Quote Originally Posted by jackie schmidt View Post
    Isnít that about what a factory Remington 700 has?
    I'd guess you're right.... I'll go over and measure one here when I get off the mill

  2. #47
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    Quote Originally Posted by coyotechet View Post
    Here is how I see it. I know I am not even close to being a machinist. I see it like a teeter-totter if one indicates at the pivot (the throat of the chamber) TDC then at the muzzle end TDC and knows that the very breech end has runout. They say first drill out then boring corrects the lineament of the chamber. But like a teeter-totter if there is runout on one end (throat to breech for a couple inches) then there has to be run out forward of the pivot (throat) for the same amount as the breech had. Now if you use the Gordy method, indicate throat TDC then at the very breech end TDC you straighten out (chamber throat) of the teeter-totter and then bore in front of the pivot point is also straighten out but the muzzle end now has the run out and for myself I have never seen it to be a problem on target or sighting the barrel in. I know I am stepping in a puddle.

    Chet

    OK.... maybe we agree here?

    Even if "Gordie's Method" of teetering the totter is NOT USED. Even if a guy thinks it's silly to flop the muzzle around..... Can you tell me of a better, or even a good way to locate that pivot point on, say a 30-06? Or, for those of us who sometimes shoot beyond 300yds..... how would you recommend dialing in the throat on a big .338?

    (This is the point where most guys go "h'rump, this is why magnums are stupid")

    I submit that properly used, Gordies extension method is freakin' brillion't...... And it allows a mere mortal like me'self, with cheap equipment to make deer rifles that shoot like STINK!

  3. #48
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    Quote Originally Posted by alinwa View Post
    I'd guess you're right.... I'll go over and measure one here when I get off the mill
    So I measured some, only found 5 but..... evidently there's different rules for hammered barrels as they all measured substantially over 1.250 with prox 1.254 being common, one at 1.258

  4. #49
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    Can you tell me of a better, or even a good way to locate that pivot point on, say a 30-06? Or, for those of us who sometimes shoot beyond 300yds..... how would you recommend dialing in the throat on a big .338?

    I use a grizzly rod and then check the runout if any with a Mitutoyo 513-512 with a long probe which allows me to take a reading up to 4" into the bore after drilling. I have checked the runout of the Long Probe Mitutoyo against a .0001 Brown&Sharp indicator and always get a runout reading of .0005 or less which I call good.

    Chet

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    Last edited by coyotechet; 01-24-2020 at 04:09 PM.

  5. #50
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    What might the actual reading be in tenths or thousands when reaching in there four inches. Compared to a standard tenths indicator or am I missing something.

  6. #51
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    . I have checked the runout of the Long Probe Mitutoyo against a .0001 Brown & Sharp indicator and always get a runout reading of .0005 or less which I call good.

    That is what I have already done, I chucked up a Deltronic pin and then with long probe Mitutoyo zeroed it to where the dial (pointer) does not any longer move then check the Deltronic pin that I just zeroed with my .0001 Brown & Sharp indicator and the runout on the Brown and sharp is always .0005 or less so I just call that good enough. P.S Have used other .0001 to do the checking of the pin also. Something like the picture below.
    Chet


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  7. #52
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    Quote Originally Posted by coyotechet View Post
    That is what I have already done, I chucked up a Deltronic pin and then with long probe Mitutoyo zeroed it to where the dial (pointer) does not any longer move then check the Deltronic pin that I just zeroed with my .0001 Brown & Sharp indicator and the runout on the Brown and sharp is always .0005 or less so I just call that good enough. P.S Have used other .0001 to do the checking of the pin also. Something like the picture below.
    Chet


    Click image for larger version. 

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    Is that your picture? Thatís got the making of a meme! Can I steal it, if itís yours?

  8. #53
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    Build a chuck that will hold the barrel by itself without NEEDING a spider. Dial it in with nothing touching the muzzle end, THEN snug the spider up only for support. If the barrel moves when you loosen up the spider, well, you were bending it.
    Last edited by zfastmalibu; 01-25-2020 at 01:50 AM.

  9. #54
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    Is that your picture? Thatís got the making of a meme! Can I steal it, if itís yours?
    Yes my picture and posted it on the web so it is yours to do what you want, thanks for asking.

    Chet

  10. #55
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    Red face

    It looks like Chet needs to invest in some better quality indicators.

    Nice collection there Chet.

    Joe Hynes

  11. #56
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    .
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  12. #57
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    Quote Originally Posted by Rubicon Prec. View Post
    .

    Well Done.... Bravo

    (I was afraid you were gonna' take it somewhere's else entirely......)

  13. #58
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    QUOTE=Rubicon Prec.=Click image for larger version. 

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    Some so called gunsmiths only have one indicator. And think they indicated in GOOD gun work. Take my word not all indicators READ any where near true. I have tested many high dollar Top Brand name indicators and sent them back to the supplier for exchange. I Tested them because I want to do good GUNSMITH work.
    With out GOOD ACCURATE indicators it is hard to do GOOD GUNSMITH WORK.

    Chet.

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    Last edited by coyotechet; 01-25-2020 at 11:07 PM.

  14. #59
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    Quote Originally Posted by coyotechet View Post
    Some so called gunsmiths only have one indicator. And think they indicated in GOOD gun work. Take my word not all indicators READ any where near true. I have tested many high dollar Top Brand name indicators and sent them back to the supplier for exchange. I Tested them because I want to do good GUNSMITH work.
    With out GOOD ACCURATE indicators it is hard to do GOOD GUNSMITH WORK.

    Chet.

    Click image for larger version. 

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    There's a lot of good info on indicators here: http://www.longislandindicator.com/. I was surprised to find out that they don't think too highly of (newer) Mitutoyo or B&S. Their top pick is BestTest/Tesa/Interapid (all the same parent company). Also the place to buy extended tips for anyone who's been reading along and wondering about that.

    GsT

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