Author Topic: Optimal bullet diameter in an autoloader  (Read 718 times)

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Offline Chinook

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Optimal bullet diameter in an autoloader
« on: May 06, 2008, 09:31:48 AM »
Veral,

Just received your latest shipment of LBT moulds and cast a couple dozen of the 165gr. WFN .401s for my .40 S&W (SIG).  The bullets dropped from the mould at exactly .4020.  Out of curiosity, I drove one of these through the SIG barrel and found its groove diameter to be be .4013 ~ .4014.  Would you suggest sizing/lubing these at .402 or at .401 for best accuracy and minimal leading?  I loaded one straight from the mould (no primer or powder) in a case and it chambered fine.

Thanks,
Chinook

Offline Veral

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Re: Optimal bullet diameter in an autoloader
« Reply #1 on: May 08, 2008, 05:12:10 PM »
  Since they chamber freely, shoot them at full size and you'll get best accuracy.

  As a general rule, autoloaders will shoot best with the fattest bullet that will chamber freely, this because they can't tip as much on takeoff as a slimmer bullet.  The exeption to this will be if the head space shoulder is too deep and causes lead to shave upon firing.  The only solution for this problem is to open the forceing cone a little or seat bullets so the jamb into the rifling upon chambering so the bullet is already centered before firing.  The second option is quite limited, and when limited it is because of the bullets design, not having enough bearing length, too much nose length or whatever, to allow smooth feeding.
Veral Smith