Seperating by bearing surface?

Discussion in 'Reloading' started by RangerBrad, Sep 7, 2012.

  1. RangerBrad

    RangerBrad Well-Known Member

    Messages:
    290
    Joined:
    Dec 26, 2010
    How many of yal actually seperate your hunting bullets by bearring surface? I am shooting 115gr bergers from my 25-06 and find this task to be miserable. I also find I'll have half my bullets in 1 pile and the other half spread in 4 diffrent other piles. Seems like I'm loosing alot of bullets. Brad
     
  2. Aldon

    Aldon Well-Known Member

    Messages:
    718
    Joined:
    Sep 4, 2009
    I do for my 6.5-06AI.

    I was having flyers and this cured it.

    I find that the issue for me was that the distance to lands is critical for this rifle more than others.

    Once I had several hundred separated I had about 8 groups and 4 were obviously more significant than the others I then did measurements to the lands with each of the groups and recorded so when I load them I know exactly how far to seat them.

    For the really small groupings or stacks, I use them for fireforming new brass and for fowling.
     

  3. Joe King

    Joe King Well-Known Member

    Messages:
    1,390
    Joined:
    Apr 29, 2012
    Bergers I don't, the 7 shoots em better than I can shoot.................:)
     
  4. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,262
    Joined:
    Aug 10, 2003
    I don't.
    Don't see how it would matter
     
  5. Sully2

    Sully2 Well-Known Member

    Messages:
    2,480
    Joined:
    Feb 28, 2011

    My question is WHY??? Dont know what you are using as a "gauge" to separate them....but if you think the same weight....same style bullet....from the same manufacture...can be separated into categories by any device you easily have hands on....compared to the bullet maker themselves ....then you go right ahead. I'll spend my time watching the Coke machine sweat at the gas station!!!!!:rolleyes:
     
  6. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,262
    Joined:
    Aug 10, 2003
    Sully, bullet companies make them as consistent as they can, but they do not blueprint them.
    They don't individually measure & separate each bullet into lots.
    IMO, they should for any bullet designated 'MATCH', and of course those bullets should cost more.
    This, so that a box of MATCH bullets stamped with a G1BC of .612, actually measure to a blueprint and hold a calculated G1BC of .612. Every external attribute of these bullets; End dia, Base length, Base angle, Bearing length, Bearing dia, Nose length, Ogive radius, Meplat dia, would fall within a declared tolerance -while combining to match in BC.

    I seriously doubt this has ever happened, so if we're to get this we'll have to do it ourselves, and it is possible. But, the cost in it for us, is not yet viable.
    A practical approach, Keyence IM-6500: https://www.youtube.com/watch?v=nBzItektFK0&feature=endscreen&NR=1
    Adapt this to an assembly line, and automate bullet separation into lots based on software set parameters/tolerances/ final calculations. ~$25K
    If I stumble into the money, I'll do it & offer true MATCH bullets on the side to recoup costs.

    But what we're doing today, manually with common hard measure, only brings more questions than answers. BEARING: Why would we care at all about this single parameter? And how are we actually separating this component in measure?

    With a 105LAP giving me a calculated ICAO G1BC of .495 @ 3kfps:
    -If I reduce bearing by 10thou -by extending base length and nose length 5thou each(all else same), my BC changes to .497
    -If I increase bearing by 10thou -by reducing base length and nose length 5thou each, my BC changes to .492
    -If I reduced bearing 10thou -by extending the nose alone by 10thou, my BC changes to .498
    -If I reduced bearing 10thou -by extending the base alone by 10thou, my BC changes to .496
    But, nose changes can mean ogive radius change and/or meplat dia change, and every 1thou of MD on this bullet means .003 in BC adjust -by itself.

    So when you lump base and bearing length together into one comparative term, and nothing else, what could it possibly mean that you would base any action on?
    Let's say it's an unknown, but small BC variance. Then what does it mean as far as friction?
    I have not seen a test yet to isolate a ballistic affect from bearing born friction.
    Have any of you?

    I know that I could not see it using 139LAPs acrossed 20' screen spacing with an Oehler.
    I know that I could not see it as seating force variance using an electronic loadcell built into my Sinclair expander.
    It seems like the first action anyone takes after measuring bullets is to ask on a forum about their numbers.
    Well, it's my contention that nobody knows what the numbers mean(until I'm proven wrong).

    It's very much like weighing brass.. Another easy shortcut leading only to assumptions in meaning..
     
    Last edited: Sep 9, 2012
  7. Sully2

    Sully2 Well-Known Member

    Messages:
    2,480
    Joined:
    Feb 28, 2011

    And that TOLERANCE is what Im referring to.....Its miniscule at best and what equipment does ANY individual possess that can separate the highs from the lows and retain just the nominal??? Once they were seperated...then people such as the OP whine he's tossing a lot of slugs away..!!!!

    What does he assume he is going to end up with? Slugs that go into 1 hole at 500 yards or more?

    Its a total waste of time..pure and simple
     
  8. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    I've had no problem getting Sierra's 30 caliber HPMK's of 155, 180, 190 and 200 grain weights right out of the box (no measuring in any way) to shoot under 5/8 MOA all the time (in good conditions when tested with 15 to 20 shot groups) at 1000 yards.

    One person took a bunch of Lapua 185-gr. FMJRB 30 caliber match bullets and spun them in a tool that measured how well they were balanced. Some quite unbalanced flew out of the collet holding them in a Dremel Moto Tool spinning at 30,000 rpm. About half were perfectly balanced as indicated by minimum current needed to spin the motor; the more they were unbalanced, the more current was needed to spin the motor up to speed. Those perfect ones were shot into several 10-shot groups at 600 yards; they ranged from about 1.5 inch down to under .7 inch. A 40-shot test of them went into 1.92 inch; about normal compared to what the 10-shot groups' sizes were. Before spinning them for a balance test, they were put in an optical collimator that showed slight shape errors in the ogive and rebated base as well as length overall. That didn't seem to matter as it' normal when the same dies coin, cup, draw and core with lead as pure as can be, shape a sheet of jacket material that's never perfect in its metalurgy makup and dimensions.

    Most match bullets have a slight unbalance that causes their BC to vary 1% or more as they wobble different amounts in flight. Only bullet spinning true on their shape axis have the lowest and most constant BC. The more they wobble, the more BC drops. And a 1 to 2 tenths grain in weight change is negligible as far as BC is concerned.