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Rifles, Reloading, Optics, Equipment
Reloading
sorting brass and bullet data for best accuracy
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<blockquote data-quote="Bart B" data-source="post: 691354" data-attributes="member: 5302"><p>All the prep and measure stuff I've done over the years with .308's and a couple of 30 caliber magnums is rather skimpy. But it's worked to produce no worse than sub 5/8 MOA accuracy with 20+ shot groups through 1000 yards.</p><p></p><p>Cases; weigh 20 and get the average. Turn the necks on those with more than .001 inch spread in wall thickness. Then weigh all of them putting those +/- .75% of the average (a 1.5% weight spread) in one group; about 2/3rds of the cases will usually be in this middle group. The lighter ones in a "lite" group and the heavier ones in the "heavy" group. Then keep each group separate for shooting and reloading. While some folks sort by case capacity, I've done that and found it's no better than sorting by weight and a lot less time, mess and cleanup. Forget primer pocket and flash hole prepping; there's a bigger spread in primer pellet heat and pressure output than making the flame have an easier path to the powder.</p><p></p><p>Bullets, get good ones then shoot 'em. Sierra and Berger match bullets are excellent. Sorting by weight's the least important; 1/2 grain difference is insignificant in what change in BC that'll have. Sorting by some dimension's a waste of time, too. Been there, done that and all without benefit. Unless you can spin bullets at 30 thousand rpm and measure their unbalance sorting out those that don't fly out of the collet holding them and are the best balanced. I don't think it's worth measuring and weighing bulets.</p><p></p><p>Powder, for ranges 300 yards and less, meter powder directly into the case. Practice so the charge weight spread is no more than .3 grain; 3/10ths grain. For longer ranges, weigh powder to a 1/10th grain spread; 0.1 grain. There's more spread in the chemistry of exact charge weights that cause different shaped pressure curves and peak pressure than what a 1/10th grain difference in powder will cause. Use medium speed powders; not those slow ones that give high velocity with big spreads. Stay far, far away from ball powder.</p><p></p><p>Primers, milder ones tend to give better accuracy. But the Wolff standard and magnum primers are very uniform and are the favorite of most high power competitors.</p><p></p><p>Finished round, bullet runout not to exceed .003 inch. Most any seating die will make straight ammo if the case neck's straight and well aligned with the shoulder and case axis. I prefere to seat bullets for best accuracy touching the lands; seated several thousandths long in case necks with just enough tension to hold them in handling and loading. This lets the bullet seat back when the round's chambered and have the same jump distance and start up resistance for every shot. As the head to shoulder length of sized cases have a small dimensional spread, getting the same distance from case head to some diameter on the seated bullet ends up with different jump to the lands distance.</p></blockquote><p></p>
[QUOTE="Bart B, post: 691354, member: 5302"] All the prep and measure stuff I've done over the years with .308's and a couple of 30 caliber magnums is rather skimpy. But it's worked to produce no worse than sub 5/8 MOA accuracy with 20+ shot groups through 1000 yards. Cases; weigh 20 and get the average. Turn the necks on those with more than .001 inch spread in wall thickness. Then weigh all of them putting those +/- .75% of the average (a 1.5% weight spread) in one group; about 2/3rds of the cases will usually be in this middle group. The lighter ones in a "lite" group and the heavier ones in the "heavy" group. Then keep each group separate for shooting and reloading. While some folks sort by case capacity, I've done that and found it's no better than sorting by weight and a lot less time, mess and cleanup. Forget primer pocket and flash hole prepping; there's a bigger spread in primer pellet heat and pressure output than making the flame have an easier path to the powder. Bullets, get good ones then shoot 'em. Sierra and Berger match bullets are excellent. Sorting by weight's the least important; 1/2 grain difference is insignificant in what change in BC that'll have. Sorting by some dimension's a waste of time, too. Been there, done that and all without benefit. Unless you can spin bullets at 30 thousand rpm and measure their unbalance sorting out those that don't fly out of the collet holding them and are the best balanced. I don't think it's worth measuring and weighing bulets. Powder, for ranges 300 yards and less, meter powder directly into the case. Practice so the charge weight spread is no more than .3 grain; 3/10ths grain. For longer ranges, weigh powder to a 1/10th grain spread; 0.1 grain. There's more spread in the chemistry of exact charge weights that cause different shaped pressure curves and peak pressure than what a 1/10th grain difference in powder will cause. Use medium speed powders; not those slow ones that give high velocity with big spreads. Stay far, far away from ball powder. Primers, milder ones tend to give better accuracy. But the Wolff standard and magnum primers are very uniform and are the favorite of most high power competitors. Finished round, bullet runout not to exceed .003 inch. Most any seating die will make straight ammo if the case neck's straight and well aligned with the shoulder and case axis. I prefere to seat bullets for best accuracy touching the lands; seated several thousandths long in case necks with just enough tension to hold them in handling and loading. This lets the bullet seat back when the round's chambered and have the same jump distance and start up resistance for every shot. As the head to shoulder length of sized cases have a small dimensional spread, getting the same distance from case head to some diameter on the seated bullet ends up with different jump to the lands distance. [/QUOTE]
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sorting brass and bullet data for best accuracy
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