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twist rate for a .300 RUM

 
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Old 08-24-2008, 09:36 AM
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Re: twist rate for a .300 RUM

Hey guys you are right. But I just cann't get excited about the 240 SMK. Too heavy to launch with much speed even from the 300 RUM. Better to go with the Edge and a 300 SMK. Also, he was asking about bullets of 200 to 220, not 240.

I think you will agree that in general the 308 bullets are less aggressively designed for bc than the 7mm. Compare Bergers or the JLK VLD bullets in 7mm vs 308. JLKs 7mm 180 has a bc of 0.735 due to an 18 caliber radius ogive. While the 308 210 has a bc of 0.665 due to a 15 caliber radius ogive. You can just look at their picture of the two bullets and see the difference.

Would you agree with my assesement that the larger the caliber, the easier it is to build a high bc bullet? Just think of a 224 compared to a 510. The Hornady 510 caliber Amax has a bc of 1.05. You'll never do that in 224 or 243. So the 308 have gotten short shift on bc compared to 7mm.

If I were building a 300 RUM, and I'm thinking about it, I'd certainly go no slower than a 10 twist. In fact I'd probably go an 8 or 9. Why, because one needs to shoot bullets that are high bc for their weight to really get a long range shooter. The Berger 210 will do just as well on wind drift as the 240 SMK because of it's higher speed. It is probably also more reliable on game. But you need both speed and high bc to get the best possible on wind drift.

I'd probably go faster than 10 twist because I'd be hoping for better bullets in the 200-220 wt range that are longer and higher bc. Henson has them now, not proven but they're here. Even Berger will get around to this some day. I'd want to be prepared. But that's just me.

Just my thoughts. Thanks for yours!!

Last edited by Varminator 911; 08-24-2008 at 09:40 AM.
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  #9  
Old 08-24-2008, 10:22 AM
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Join Date: Feb 2005
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Re: twist rate for a .300 RUM

JonA pushes the 240 SMKs near 3000 FPS out of his 300 RUM not exactly creeping IMHO. I'll agree the more agressive BC bullets with long olgivals can be finicky to get them to shoot small groups, YMMV.
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Last edited by jwp475; 08-24-2008 at 10:25 AM.
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