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Rifles, Reloading, Optics, Equipment
Reloading
.257 Weatherby Magnum
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<blockquote data-quote="Bart B" data-source="post: 1149859" data-attributes="member: 5302"><p>Best accuracy the .300 H&H match rifles produced in the late 1930's when Ben Comfort did that in 1935 was about 15 inches at 1000 yards. They all used new cases to do it. His record was broken in almost every year later by military team members using new cases.</p><p></p><p>The problem is, belted cases are not full length resized like rimless ones. Rimless ones get their body sized down from the pressure ring forward. Belted ones typically have a ridge left on their first firing as the belt's back a couple thousandths from the chamber headspace stop when fired; it stays there and interferes with how the case slams forward from firing pin impact on the next firing. That causes irregular barrel whipping before the bullet leaves the barrel.</p><p></p><p>When the 300 H&H was finally replaced with a more accurate cartridge in the 1960's (Fred Huntington's .30-.338 and the .300 Win Mag) as a long range match cartridge, people winning and setting records with it got better accuracy with new cases than conventional full length sized ones. Neck only never produced consistent accuracy. So they cut the top and bottom of a full length sizing die off, then used it to resize a full length sized case squeezing down that ridge and sizing the case back to virtual new case diameters all the way back to the belt. Finally best accuracy (about 6 inches at 1000 yards) was possible and consistent for testing ammo. Larry Wilis' collet die for belted cases now does the same thing.</p><p></p><p>Prior to that time when the H&H round was popular, the best scores were shot with new cases. As did the military teams shooting Win 70 .300 H&H bull guns in long range matches. They tried full length sizing .30-.338 and .300 Win Mag cases in the '60's but gave up and used new ones. Civilians used that body die before or after full length sizing their fired belted cases Such improvements were the reason why the target scoring rings were reduced in the early 1970's down from their original sizes set around 1900.</p><p></p><p>In my own tests with .30-.338's, neck only sizing produced 10 to 15 inch groups at 1000 yards. New cases or proper full length sized ones resized with a body die all the way to the belt shot under 6 inches. 15 to 20 shot tests for credibility.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1149859, member: 5302"] Best accuracy the .300 H&H match rifles produced in the late 1930's when Ben Comfort did that in 1935 was about 15 inches at 1000 yards. They all used new cases to do it. His record was broken in almost every year later by military team members using new cases. The problem is, belted cases are not full length resized like rimless ones. Rimless ones get their body sized down from the pressure ring forward. Belted ones typically have a ridge left on their first firing as the belt's back a couple thousandths from the chamber headspace stop when fired; it stays there and interferes with how the case slams forward from firing pin impact on the next firing. That causes irregular barrel whipping before the bullet leaves the barrel. When the 300 H&H was finally replaced with a more accurate cartridge in the 1960's (Fred Huntington's .30-.338 and the .300 Win Mag) as a long range match cartridge, people winning and setting records with it got better accuracy with new cases than conventional full length sized ones. Neck only never produced consistent accuracy. So they cut the top and bottom of a full length sizing die off, then used it to resize a full length sized case squeezing down that ridge and sizing the case back to virtual new case diameters all the way back to the belt. Finally best accuracy (about 6 inches at 1000 yards) was possible and consistent for testing ammo. Larry Wilis' collet die for belted cases now does the same thing. Prior to that time when the H&H round was popular, the best scores were shot with new cases. As did the military teams shooting Win 70 .300 H&H bull guns in long range matches. They tried full length sizing .30-.338 and .300 Win Mag cases in the '60's but gave up and used new ones. Civilians used that body die before or after full length sizing their fired belted cases Such improvements were the reason why the target scoring rings were reduced in the early 1970's down from their original sizes set around 1900. In my own tests with .30-.338's, neck only sizing produced 10 to 15 inch groups at 1000 yards. New cases or proper full length sized ones resized with a body die all the way to the belt shot under 6 inches. 15 to 20 shot tests for credibility. [/QUOTE]
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Reloading
.257 Weatherby Magnum
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