How close is close enough?

Discussion in 'Reloading' started by Hotrod617, Aug 18, 2012.

  1. Hotrod617

    Hotrod617 Active Member

    Messages:
    26
    Joined:
    Mar 20, 2012
    When seating bullets???

    I measure my bullets by the ogive and separate in lots of .002.

    When seating, I get a spread by as much as .005. measuring again by the ogive (looking for 3.038 and getting 3.035 - 3.040). I seldom see the same measurement back to back. I am using redding dies with micro seating adjuster. I have cleaned the seating die to make sure no trash is up there, and I make sure the bullets are clean.

    I know this may be a little anal, so I need to know if everyone gets this or is there something I am doing wrong???


    Bill
     
    Last edited: Aug 18, 2012
  2. Joe King

    Joe King Well-Known Member

    Messages:
    1,390
    Joined:
    Apr 29, 2012
    If your bullet comparator doesn't read from the same place on the ojive as the seating plug contacts the ojive then the only measurement that means anything is after the bullet is seated. That's only in reference to the length your looking for. :)

    Whats your grouping tell you? If your still getting .5 moa at 300 then I wouldn't worry to much about it.
     

  3. Hotrod617

    Hotrod617 Active Member

    Messages:
    26
    Joined:
    Mar 20, 2012
    Joe,

    thanks for the reply.

    I guess my problem (question) is does everyone get as much as a .005 spread when seating??

    Oooops... I also didn't think about it till you said something, I did not measure brass......

    Crap, I'm such a dumb azz :(

    That's the thing I missed.

    bill
     
  4. Joe King

    Joe King Well-Known Member

    Messages:
    1,390
    Joined:
    Apr 29, 2012
    It depends on the bullets your using. With custom I've seen it be spot on, usually withing 0.002"

    Mass produced yea 0.005 is pretty normal from what I've seen.

    your brass length won't effect that, your seating die doesn't care how long your brass is (within reason)
     
  5. Greyfox

    Greyfox Well-Known Member

    Messages:
    3,709
    Joined:
    Jan 21, 2008
    I'm usually .002. But have seen variations as much as .005. Doesn't seem to have a big impact unless I'm working with seating distances at or in the lands but I avoid that for hunting loads usually keeping them away from the lands, usually +.0.010' out.
     
  6. lamiglas

    lamiglas Well-Known Member

    Messages:
    603
    Joined:
    Mar 20, 2008
    With smks and comp redding dies, even after sorting bullets, mine vary by up to .oo5, but usually closer to .002-.003. I rough seat mine .005 to long, measure them, sort them in groups by how many thousands they are to long, adjust the micrometer and then final seat to desired oal. I cannot confirm this is neccesary. i do this because Carlock showed me this when I built my first edge and have been doing it all along.
     
  7. Joe King

    Joe King Well-Known Member

    Messages:
    1,390
    Joined:
    Apr 29, 2012

    I'm not convinced that some of the sorting we do has any real effect the we as individual shooters can realize. Some of it is necessary to get the best accuracy but who knows. Take good custom bullets, I personally quit sorting them at all, and still get grouping that amazes me. With say common polymer tipped bonded core bullets though, I sort them before I do anything else.

    I am a firm believer though that a well developed load and a well tuned rifle will perform far better than all but the very best shooters, and even then the conditions have to be just so.
     
  8. Hotrod617

    Hotrod617 Active Member

    Messages:
    26
    Joined:
    Mar 20, 2012
    thanks for the help guys.

    Like I said in the first post I am a little anal. Just cant figure the variance in seating depth. Seems like with something that can be adjusted down to the thousandth, you should be able to get repeatability...



    Bill
     
  9. Joe King

    Joe King Well-Known Member

    Messages:
    1,390
    Joined:
    Apr 29, 2012
    tolerances in the Ojive, the higher the mass production the looser those tolerances will be. It's just the nature of the beast.
     
  10. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,265
    Joined:
    Aug 10, 2003
    Whether it'll affect your results depends on things unknown to me(but still existing).
    Once you've actually tested for best seating with a couple guns you'll come to recognize that 5thou CAN have a big affect,, but then it might not.

    My seating does not vary by even 1thou. It is for the most part -exact.
    My shoulder bumps are also pretty damn close to exactly 1thou, to begin(settle variance can shift ~-.0005 over time).
    So I know that it can be done & how to do it.

    I also know what mungs it all up:
    -Not qualifying ogive radius
    -Not using inline die seating(with an arbor press)
    -Not turning necks to same thickness
    -Not trimming necks to same length
    -Seating bullet bearing too near neck shoulder junction
    -Big variances in bullet bearing
    -FL sizing necks
    -Over cleaning
    -Over annealing
    -Over sizing
    -Inconsistent/bad mouth preps
    -Bullet mismatching seater plug, bad contact angles, bottoming, or contacting too high on nose
    -Inconsistent neck lube
    -Inconsistent/Poor measurement

    You're probably thinking this is ridiculous, but with only a few more items added you can also address runout, headspace, capacity variance, and ES.
    This allows for better quality in load development.

    Anyway, test for best seating with your load, work down this list, & decide how and where you should go with it.
     
  11. Varmint Hunter

    Varmint Hunter Well-Known Member

    Messages:
    2,522
    Joined:
    Dec 26, 2001
    A few things that I've noticed that result in inconsistent OAL when measured from the ogive:

    dirty necks (inside of course)
    mixed brass (diff mfg and/or diff number of reloads) both should be avoided
    bullet bases that touch or compress the powder in the case when seated
     
  12. Gene

    Gene Well-Known Member

    Messages:
    1,326
    Joined:
    Jan 23, 2007
    For hunting loads, .005" variance is fine. Competition loads should be not more than .001" with CUSTOM bullets. Hunting bullet ogives can vary a lot. And as others have stated, there are numerous fixes.
     
  13. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    Amont all the topics and facets of reloading, the one that, to me, seems to have the greatest range of beliefs, opinions, importance and all that other "exacting" stuff is where on the cartridge axis should bullets be seated for absolute consistancy in how far they have to move to the lands when fired. Consider the following......

    All the jackets used in making a batch of bullets don't get shaped to identical dimenions in the final stage of manufacture where the front part's sized to a point; they all don't have the same distance from their tip or some other small diameter near it back to some diameter on their ogive back where the rifling first touches it.

    All the bottleneck cases headspacing on their shoulders don't have the same head-to-shoulder dimension; that tolerance effects how far the seated bullet moves forward before it touches the rifling because the case shoulder's hard against the chamber shoulder when the round fires.

    All bottleneck cases headspacing on their shoulders have their shoulder set back a thousandth or more by firing pin impact; that changes the bullet's jump-to-rifling distance when the round fires.

    When all these variables add up, they'll make the bullet's jump to the rifling vary a few to several thousandths. It'll never have zero tolerance as long as bullets are seated some distance off the lands. Does that make a difference accuracy wise? Maybe; maybe not. Shoot some 20-shot groups to find out. I've seen rifles shoot sub 3/4 MOA at 1000 yards with bullet jump spreads of 5 thousandths. Even semiauto service rifles used in competition have shot under 2/3 MOA at 600 with a 7 thousandths spread in bullet jump as well as up to 3 thousandths runout.

    The only way anyone (in my opinion) will get zero spread in bullet jump distance is to use a light neck tension on bullets then seat 'em out far enough to be pushed back into the case neck when chambered and fired. Regardless of all the other tolerances in places mentioned earlier, this method eliminates all of them.

    Too bad there's no bullet seating die for rimless bottleneck cases that uses the case shoulder as a reference instead of the case head. That would remove one of the variables.
     
    Last edited: Aug 19, 2012
  14. D.ID

    D.ID Well-Known Member

    Messages:
    838
    Joined:
    Dec 24, 2008
    What kind of bullets are we talking about? I have always found bergers to be real close and easy to get back to back numbers, sierra a little more slop, nosler a whole lot more slop.
    Seating depths have a node (for lack of a better term) if those low single digit discrepancies show significantly larger groups, you may be right on the threshold of one and may need to go in or out a couple thousands to settle down in the middle. I use to fight this with some "hunting" bullets but not usually with the match bullets.