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Rifles, Reloading, Optics, Equipment
Reloading
Neck turning tool & Advice please
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<blockquote data-quote="Bart B" data-source="post: 343622" data-attributes="member: 5302"><p>There are folks who get excellent accuracy from SAAMI spec chambers for 30 caliber cartridges with .344" chamber neck diameters and .335" average diameter loaded round neck diameter on cases with .001" spread in neck wall thickness. Even with powder charges thrown from a measure with 1/3 grain spread, up to .003" bullet runout with new, unfired cases loaded on two Dillon 1050 progressives, they've produced sub 1/2 MOA 20-shot test groups at 600 yards and no worse than 2/3 MOA in a couple dozen different rifles. With weighed charges in new belted magnum 30 caliber cases, sub 7/10ths MOA 30-shot groups at 1000 yards. The best semiauto 30 caliber military rifles would shoot all day long inside 2/3 MOA at 600 yards with a good lot of mass produced match ammo (none of them shot that well with reloads).</p><p></p><p>IMHO, tight chamber necks and very uniform case neck walls aren't all that important. If these were critical for accuracy that good, the rifles and ammo having the above track record would not have done that well. I'm not referring to those occasional (rare?) few shot groups that set records and win benchrest matches. Those micro clusters are rarely, if ever, repeated by the same rifle-ammo combination, so they're not what the accuracy is one can count on all the time. The vast majority of groups a rifle shoots are much larger than their smallest ones, but most folks talk only about the smallest ones their hardware produces. I'm not impressed by those tiny, few-shot groups that set the records; they're more luck than reality.</p><p></p><p>Forster case trimming tools work great. With the piloted cutter chucked in a drill press and the base bolted/clamped below it, one can trim a bunch of cases pretty fast and uniform. Deburring the outside of the case mouth with a traditional tool is easy and reasonably fast. But I don't like the case mouth end of those tools; they leave a too rough and too sharp an angle at the inside of the case mouth that often scrapes off bullet jacket material unbalancing the bullet. You may need to use a magnifying glass to see the copper jacket material scraped off a seated bullet. I prefer and Easy-Out screw extractor of the size that a case mouth just fits about half way up its spiraled flutes. Turning it clockwise peens and smooths the edge of the trimmed case mouth at a better angle then using a bore brush chucked in a drill press cleans and smooths up that edge even better. Bullets seated in such case necks don't get jacket material scraped off.</p></blockquote><p></p>
[QUOTE="Bart B, post: 343622, member: 5302"] There are folks who get excellent accuracy from SAAMI spec chambers for 30 caliber cartridges with .344" chamber neck diameters and .335" average diameter loaded round neck diameter on cases with .001" spread in neck wall thickness. Even with powder charges thrown from a measure with 1/3 grain spread, up to .003" bullet runout with new, unfired cases loaded on two Dillon 1050 progressives, they've produced sub 1/2 MOA 20-shot test groups at 600 yards and no worse than 2/3 MOA in a couple dozen different rifles. With weighed charges in new belted magnum 30 caliber cases, sub 7/10ths MOA 30-shot groups at 1000 yards. The best semiauto 30 caliber military rifles would shoot all day long inside 2/3 MOA at 600 yards with a good lot of mass produced match ammo (none of them shot that well with reloads). IMHO, tight chamber necks and very uniform case neck walls aren't all that important. If these were critical for accuracy that good, the rifles and ammo having the above track record would not have done that well. I'm not referring to those occasional (rare?) few shot groups that set records and win benchrest matches. Those micro clusters are rarely, if ever, repeated by the same rifle-ammo combination, so they're not what the accuracy is one can count on all the time. The vast majority of groups a rifle shoots are much larger than their smallest ones, but most folks talk only about the smallest ones their hardware produces. I'm not impressed by those tiny, few-shot groups that set the records; they're more luck than reality. Forster case trimming tools work great. With the piloted cutter chucked in a drill press and the base bolted/clamped below it, one can trim a bunch of cases pretty fast and uniform. Deburring the outside of the case mouth with a traditional tool is easy and reasonably fast. But I don't like the case mouth end of those tools; they leave a too rough and too sharp an angle at the inside of the case mouth that often scrapes off bullet jacket material unbalancing the bullet. You may need to use a magnifying glass to see the copper jacket material scraped off a seated bullet. I prefer and Easy-Out screw extractor of the size that a case mouth just fits about half way up its spiraled flutes. Turning it clockwise peens and smooths the edge of the trimmed case mouth at a better angle then using a bore brush chucked in a drill press cleans and smooths up that edge even better. Bullets seated in such case necks don't get jacket material scraped off. [/QUOTE]
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Neck turning tool & Advice please
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