Low NT 6br

Discussion in '6BR, 6BR Improved & Wildcats' started by Cory porter, Feb 10, 2019.

  1. Cory porter

    Cory porter Silver $$ Contributor

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    have a question about 6br neck tension. I have a hall action with a Abc barrel on it, 8 twist shooting 108g Berger. It is a no neck turn and currently I am using a 267 bushing with the Bullet roughly 8-10thou in the lands.

    Base to ojive is 2.840C and after messing with it last night I realize if I chamber a dummy round like this after extracting it the bullet is being pushed back in the case roughly 7thou. The gun shoots great, would you guys leave it or test with more neck tension. I did the same test with a 266 bushing and it didn’t move, but you could tell it was slightly tougher to close the bolt.
     
  2. 10XSHOOTER

    10XSHOOTER Gold $$ Contributor

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    Leave it alone! shoot it as it is!
     
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  3. oldduc

    oldduc Silver $$ Contributor

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    Never change anything that is shooting "great". It will stop shooting great soon enough, and then you can change it.
     
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  4. SPJ

    SPJ Silver $$ Contributor

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    2.840 CBTO?
    Gotta be a typo
     
  5. Cory porter

    Cory porter Silver $$ Contributor

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    1.840

    2.840 with Hornady comparator
     
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  6. Texas10

    Texas10 Gold $$ Contributor

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    Mental gymnastics aren't my forte, so I put my old and well used dial caliper back in the tool box and bought a digital one. They're stupid cheap anyway, no why not? I'd wasted too many shooting sessions to a loading error in seating depth.

    It doesn't seem possible that when seating to 8 to 10 thou into the lands, your bullet is being seated deeper by seven when chambering. But as others suggest, if it ain't broke, don't fix it!
     
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  7. WyleWD

    WyleWD Gold $$ Contributor

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    I'd try the 266 bushing on a 5 shot group just to check it vs a 5 shot group from the 267 bushing. It might shoot fantastic instead of great. It's all guesswork and speculation until you try it. JMHO. WD
     
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  8. Cory porter

    Cory porter Silver $$ Contributor

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    It’s being pushed back into the case when chambered.

    Not sure if you’re misunderstanding me or me not understanding what you’re saying
     
  9. Texas10

    Texas10 Gold $$ Contributor

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    In my experience, I've seated a bullet long into a neck sized case, chambered it and forced the bolt close. Measuring the CBTO afterward and recording it, I then take the Hornaday LNL modified case and neck size it. Seat a bullet to .010 short of the "jam seating measurement" I just made and slide it up in the chamber with the LNL gage tool. Then retract and of course it tends to stick upon retraction indicating the bullet is seated into the lands. I keep doing this while seating shorter until no tendency to stick. This is my "touch" dimension and I've found it to be about .030 to .035 short of the "jam" seating on my 6BR.

    So if you are experiencing your bullets being pushed back during bolt closure, I'd say you're seating well into the lands, much more than 8 to 10 thou. JMOP.

    I hope this clears up what I was trying to post earlier.

    Nevertheless, it appears to me by your shooting skills, you must be doing something right! And if it ain't broke......
     
  10. Cory porter

    Cory porter Silver $$ Contributor

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    I very well could be seating longer than I think. When I did the seating test, sharpie and bullet. When chambering and there no longer being sharpie rubbed off I considered that my touch. I could be wrong

    Thankfully the 108s seem to be a great bullet and not harsh on seating depths. I’ll have to play around with it more
     
  11. gambleone

    gambleone Silver $$ Contributor

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    Sounds like you were going 1 or 2 thou further than touch with your sharpie test.
     
  12. Richard Coody

    Richard Coody Gold $$ Contributor

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    What you are doing is soft seating your bullet into the lands when you chamber the round. Not an uncommon practice at all. For one John Whidden does it.

    If it works don't change it. As a side you can preload and not worry about.cold welding and changing neck tension. You are seating the bullet when you close the bolt.
     
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