How much effect does neck tension have on volocity

Discussion in '6BR, 6BR Improved & Wildcats' started by South Prairie jim, Jul 5, 2018.

  1. milanuk

    milanuk Team Savage Gold $$ Contributor

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    When the Bob Green tool gets paired with a digital indicator that can be mated with the SortEez app to reduce the tedium/misery, I'll consider it.
     
  2. Martin52

    Martin52

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    Perhaps, but in the meantime the Bob Green tool alone is the best I have found for sorting.
     
  3. LA50SHOOTER

    LA50SHOOTER Gold $$ Contributor

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    The tools made by John Hoover work on the same principal as the Bob Green tool and also does a good job of sorting when paired with a good digital caliper. - They're not cheap but it makes it easy & pretty quick to sort larger quantities of bullets into groups down to 0.0005 bearing surface measurements.

    - Ron -
     
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  4. South Prairie jim

    South Prairie jim

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    Ron
    Wasn't there a thread a while back commenting on a bullet measuring tool with a nice Granite platform for $40- ish ?
    That was pretty cool
    Jim
     
  5. BoydAllen

    BoydAllen Gold $$ Contributor

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    Here are a few of thoughts on how to improve your cartridge case to loaded bullet ogive variation.

    Some of the variation comes from differences in ogive shape, some from differences in neck friction, and some of it comes from variations in the stretch or compression of the press linkage, if you are not using a arbor press type die.

    If you are using a threaded die that does not have a built in option to crimp, setting it up to produce a slight toggle at the top of the ram stroke will tend to make the linkage part more uniform.

    Obviously, doing whatever you can so that the insides of the necks have uniform friction is desirable, both for seating depth consistency and minimizing differences in velocity.

    There have been all sorts of schemes for dealing with differences in ogive shape. Personally I think that it may be easier to just seat everything a little long, sort by ogive to case head and then adjust the seater for each batch to produce the desired dimension.

    A couple of advantages of of an arbor presses are that they do not have linkage issues ,and because they have less mechanical advantage, it is easier to feel differences in the force required to seat bullets.
     
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  6. LA50SHOOTER

    LA50SHOOTER Gold $$ Contributor

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    Yes I believe so Jim, But that is not the Hoover Tool. The tools by John Hoover for sorting are caliber specific and it is actually part of the Meplat Trimmer Assy. - Back when I decided to get into further refining my accuracy, I started looking into tools (that are high quality) to help me not only measure bullets but as well be able to trim the Meplat to uniform my bullets and get rid of any ragged points that may exist. - Also I wanted to be able to point-up bullets. Basically, its either Whidden or Hoover if you want to be able to choose one vendor to provide an "all encompassing solution" - Back at that time, I was particularly interested in finding tooling to make the .375 caliber 350 gr. Sierra Match-Kings be a better bullet than they are off the shelf from Sierra. - John Hoover provided me a "one-of" solution to measure bullet bearing surface, trim Meplat, and a pointing die with the correct punch. - High quality tools indeed that were not cheap by any means & I had to wait a few months for him to build it.
    Well, I liked what John provided well enough to later purchase "like" tools for .338, .308, .284 & .243 calibers. - The Pointing die body for the 338 through 22 caliber is all the same, only punches to fit individual bullets are necessary which they can provide. The Meplat trimmers for each caliber are individually caliber specific so that can be pretty costly if one wants to be able to do a bunch of different calibers. - I've yet to start "pointing" bullets up and this process of pointing up I've been given words of caution on by some experience shooters / reloaders on, to not squeeze too much or bullets can be ruined to the point of making them very inaccurate. - I have used the Meplat trimmers and have measured a bunch of different bullets and sorted them. Eventually, I will point up some and test, realizing the benefit of this is seen at long range (1000 yds & beyond). - Berger bullets have been way more consistent with less variations than the other off the shelf bullet providers excluding Lapua. (The 300 gr. 338 cal. bullets by them were very consistent in bearing surface length).
    I'm yet to shoot any of the Vapor Trail or Bart's bullets but I'm sure I will eventually give them a try, especially in 6mm. - My recent focus has been around the 300 WSM and above for upcoming matches. - I have a 6mm BR that needs my attention and I plan to get to it this fall after the IBS Nationals & E2K events wrap up.

    Regards, - Ron -
     
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  7. BoydAllen

    BoydAllen Gold $$ Contributor

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    You may have not understood what the Green tool does. It is for sorting bullets based on variations in the distance between where the seating stem contacts the ogive up near the point, and where the rifling will touch just in front of the shank (cylindrical part) of the bullet. When bullets are made, the ogive is formed in the pointing die, and there will be some variation in how the jackets take the shape of the die. A bullet is inserted in the tool to the point where contact in the tools body is made about where a ogive length gauge or a barrel's rifling would touch it. The other point of contact is like a seating stem, that is designed to slide rather than remain in a fixed position. It is connected to a dial indicator that reads to .0001".
     
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  8. South Prairie jim

    South Prairie jim

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    You should engineer a tool using a VLD seating stem to measure vs a Hornday comparator
    Interesting thought
    Jim
     
  9. Laurie

    Laurie

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    My adopted solution too. Very easy to implement with a good micrometer top seater where the gradations correspond closely to one thou' on actual seating.
     
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  10. shoot4fun

    shoot4fun Gold $$ Contributor

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    Honestly, not enough of an issue that I take time to sort all my bullets by BTO. It does seem to be more important to sort when trimming meplat and/or pointing.
     
  11. South Prairie jim

    South Prairie jim

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    Gents
    I appreciate all you guys for weighing in on this topic,
    I' have learned a lot.
    Regards
    Jim
     
    Last edited: Jul 12, 2018
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