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OAl Variation with Sierra 69gr Matchking

Discussion in 'Handloading and Reloading' started by Pat M, Mar 1, 2010.

  1. Pat M

    Pat M Well-Known Member

    A question for the experts: Last night I reloaded 100 rnds of .223 with 69 grain Sierra Match King bullets at what I thought was an overall length of 2.250 inches. I was measuring as I was going along, and I was getting a variance from 2.246 to 2.257. As far as I could tell, I was applying the same amount of pressure on each round. I am using a Lee bullet seating die in the Lee Challenger press. My 55 grain Hornady FMJ and my 53 grain Match Kings are near perfect, with a variance of .002. Am I doing something wrong, or could the ogive vary that much on a match bullet?
  2. counterclockwise

    counterclockwise Well-Known Member

    I measured some bulk .308 168 OTMs while back. The extreme span for those was .01 inch. I am surprised that you would have that much with the .223 69 SMKs. Are you compressing the powder? Sometimes compressed powder pushes back. Perhaps you should pick 10 or more bullets out at random and measure just the bullet height, to get an idea if it is the bullet or the overall stackup.
  3. HJ857

    HJ857 Well-Known Member

    I'm still working on a batch of a thousand 69grain SMK's that I bought a year or so ago and this batch is by far the least consistent I've seen. I measure my seating depth using Hornady bullet comparator and the difference has been similar to what you're seeing. It's the bullets and not your seating.
  4. Pat M

    Pat M Well-Known Member

    I just measured 10 bullets randomly from the box, and I'm seeing lengths of .990 to .997. At this point in my competitive high power career it probably won't make much of a difference, but I need all the help I can get in terms of accuracy.
  5. NRA-Highmaster

    NRA-Highmaster Well-Known Member

    Measuring just the bullets, variances up to .015" aren`t out of the ordinary on the MKs.
  6. essayons21

    essayons21 Well-Known Member

    Are you measuring from the tip or the ogive?
  7. counterclockwise

    counterclockwise Well-Known Member

    I've seen some aux. tooling in the trade mags, that one can use to help true up the truncated meplat. Some of the "bulk" OTMs I have definitely show a distorted meplat. Anyway, if your bullet height (base to meplat) is ES = .015, then your COAL will vary that amount and then some due to other variances.
  8. 243winxb

    243winxb Well-Known Member

  9. kelbro

    kelbro Well-Known Member

    I have never seen that much variation with the 69gr SMKs and I have loaded 1000s of them. Redding and RCBS seater dies.
  10. Slamfire

    Slamfire Well-Known Member

    You are measuring something that has no effect on group size.

    Seat them so all will fit in the magazine and forget about it.

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