Re: 264 win mag
Okie2 claims "the ideal case capacity for 6.5 caliber is 69.6.." (grains of water I dangerously assume). What's the reasoning/theory/facts behind this claim?
The only thing I ever heard about anything being "ideal" about any centerfire rifle case is if its powder charge weight in grains for a maximum load (one producing about 53K CUP or 61K PSI) has the same number as its bore's sectional area in square millimeters. Example, a 6.5 mm groove diameter has a cross sectional area of about 33 square millimeters so it's "bore capacity" is about 33 grains of powder. This bore capacity tends to produce the best accuracy for practically all cartridges believed to be very accurate. Examples: .22 PPC, 6 PPC, .308 Win. And barrel life for best accuracy from a 1/4th MOA tack driver is about 3000 rounds for each one. Double the amount of powder over their bore capacity and barrel life is 75% less. But accuracy doesn't degrade near that much; typically about 25%. Please enlighten me.
Okie2 also states: "The best group I have ever shot was a 3 3/8 5 shot group at 1000 yards..." What's the largest group it's ever shot? I ask because folks rarely, if ever, shoot another group equalling their smallest one with any rifle-ammo combination; including benchresters. I always state my rifle-ammo group claims as the largest they've shot. That's all I (or anyone else, for that matter) can count on all the time. If one shoots 20 groups and talks only about the smallest one, in reality, he's only telling folks what's happened 5% of the time. I don't even remember what the smallest groups I've shot are. They represent the "luckiest" end of the group size spectrum. And a 5 shot group's probability of being what the rifle-ammo will shoot with a 100 shot group is about 50%
Last edited by Bart B; 12-22-2009 at 07:11 AM.