best method for checking chambering runout

Discussion in 'Advanced Gunsmithing & Engineering' started by Shawnba67, Aug 31, 2017.

  1. Shawnba67

    Shawnba67 Silver $$ Contributor

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    I recently cut my 8th chamber. And since I bought one of those long reach interapid indicators i used it to check for runout I think. I say I think because Im not certain that i actually checked anything relevant. I ran up to the throat and measured less than 0.0002(needle barely wiggling) and then measured again right at the rear most portion of chamber again got approx 0.0002ish. Is this what is being referred to as chamber runout?
    I had used same indiacator to dial in the bore to within same 0.0002(they are 0.005 marks so i use 0.0002 as more than none less than half the distance between tickmarks)
     
  2. boltfluter

    boltfluter Gold $$ Contributor

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    Shawn,

    Sounds to me like you are checking the concentricity from the bore to the end of the chamber. Which in this case sounds great. Sounds to me like you cut and dialed in a great chamber. Whatever you are doing, keep doing it! :D:D

    Paul

    www.boltfluting.com
     
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  3. Shawnba67

    Shawnba67 Silver $$ Contributor

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    Than you. Im still at the drooling mushhead stage of learning. But ill get there.
    I have soaked up as much info from this forum as i can. I wish i was smart enough to soak up more.
    So does decent concintricity indicate decent coaxial alignment? I can not wrap my head around any good way of checking that. Besides the impossible math of center line to edge devided by impecable measuring skills. I dont think i even have the right measuring tool for that, then id ned ability!
     
  4. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    What you want to see after your done chambering is that there is no runout in the bore in front of the throat, in the freebore, and rear of the chamber. This tells you nothing moved during the process and you chamber is concentric to bore. This assumes you indicate the side of the barrel you working on. If you indicate both ends you may note some runout the farther in you go but there should be none right at the throat.
     
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  5. 308sawyer

    308sawyer Silver $$ Contributor

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    If you are measuring the runout after you chambered a barrel all you are seeing is if your setup moved and if it didnt move you are measuring spindle bearing runout.
     
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  6. Hal

    Hal

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    Shawn

    It sounds like your on the right track. Always check your work.
    Indicate where the chambers throat area will be to as close to zero and recheck your set from time to time.
    After you finished chambering check the throat , neck , just below the shoulder, and rear of the chamber area.
    Than set the gear box to the correct barrel thread, set the indicator finger on threads and turn the chuck by hand and see how your threading job turned out. Check against your original numbers. That lets you check your work and if anything moved.

    Hal
     
  7. BoydAllen

    BoydAllen Gold $$ Contributor

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    What you are seeing is how well centered your throat and the rear of your chamber are on the rotational axis of the headstock spindle, and how round your chamber is at those two points. If you indicated your barrel is properly to that same axis, and it did not move than you are in very good shape. Keep doing what you are doing. It is working very well.
     
  8. Hal

    Hal

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    Shawn

    One other thing is to check your chamber to see if it's the same size as your reamer or if you cut a oversized chamber.
     
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