Bullet depth consistency

freddbear4

October 12, 2008 04:22

With brass from the same lot, trimmed to the same length, and bullets from the same lot, why is there differences in COAL when the seating die is set and locked in for the same bullet seating depth?? I have had differences of as much as 5 to 10 thousands with RCBS seating dies and 5 thousands using Redding Compition seating dies. Any insight would be appreciated.

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  mrbruce

  October 12, 2008 07:05

  I'm thinking neck tension from work hardened brass is the culprit.....

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  Tailgunner1954

  October 12, 2008 07:17

  When it comes to OAL consistancy, the difference is all in the ogive to tip variance in the bullets themselves.
  BTW, the brass length dosn't matter (and why should it?), and the neck tension would'nt come into play either.

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  Mtnlover

  October 12, 2008 07:27

  Agree with Tailgunner. Unless OAL is causing problems running cartridge through magazine, variance in bullet tip lengths will have no impact on accuracy or anything else. The press and good dies like you have will maintain very close dimensions on the ogive location, the only one that really matters.

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  dcs shooters

  October 12, 2008 08:05

  Mic the length of just the bullets and see the difference in them.
  The seating die uses the ogive to seat to the depth you want. When they swage the bullet you get a few thousands difference.

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  nononsense

  October 12, 2008 09:14

  freddbear4,
  
  A picture explains the problem. Be aware that besides the softpoint problems that hollowpoints have a similar problem with a slightly different shape. When the cup is shaped into the point by the point up die, the edges of the original cup are usually uneven which will affect the measurement of both the bullet and the OAL of the cartridge.
  
  As noted, the best technique is to use the ogive of the bullet for consistent measuring.
  
  
  
  Best.

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  freddbear4

  October 12, 2008 15:57

  Thanks guys. Your comments make sense. I use Hornady V-max and Nosler Ballistic tips. Accuracy seems good but the difference in OAL was perplexing. Especially with the Redding Compition seating dies. I'll measure each bullet to see if there is a difference. Seems like what you are saying is regardless of bullet tip configuration all bullets jump to the bbl the same distance??

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  fairlanegt390

  November 09, 2008 17:26

  One of the problems that alot of the reloading dies have is they use the tip of the bullet for seating. not the ogive. the tips are often different, tubb sells a meplate conformer that trims the tops of the bullets to the same length and square off the tips. it makes them fly tighter and more uniform reloading.

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