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Rifles, Reloading, Optics, Equipment
Reloading
How about those speer bullets?
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<blockquote data-quote="Trickymissfit" data-source="post: 756555" data-attributes="member: 25383"><p>Just looked at the specs for the 75 grain bullet in the Speer manual (have never used these in a 6mm). That bullet has a .23 B/C, and with a 1:9 barrel your way too fast for the B/C. That bullet at 3400 fps (.243) is spinning at about 270K as it leaves the muzzel! The bullet is labled as one of their "TNT" bullets made for varmit hunting. The jackets are fairly thin and will seriously be taxed at that kind of rotational speed! Even at 3000fps the speed will be a little faster than 239K rpm. But the same bullet out of a 1:14 twist barrel would be 175K rpm (3400 fps), and just about right. The over rotation speed of a bullet also tends to spread the group sizes (about 3/32" per .0001 error in the C/G). That error factor also increases as the bullet spins faster.</p><p>gary</p></blockquote><p></p>
[QUOTE="Trickymissfit, post: 756555, member: 25383"] Just looked at the specs for the 75 grain bullet in the Speer manual (have never used these in a 6mm). That bullet has a .23 B/C, and with a 1:9 barrel your way too fast for the B/C. That bullet at 3400 fps (.243) is spinning at about 270K as it leaves the muzzel! The bullet is labled as one of their "TNT" bullets made for varmit hunting. The jackets are fairly thin and will seriously be taxed at that kind of rotational speed! Even at 3000fps the speed will be a little faster than 239K rpm. But the same bullet out of a 1:14 twist barrel would be 175K rpm (3400 fps), and just about right. The over rotation speed of a bullet also tends to spread the group sizes (about 3/32" per .0001 error in the C/G). That error factor also increases as the bullet spins faster. gary [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
How about those speer bullets?
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