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Post by ke4cxp on Mar 29, 2015 7:56:11 GMT -8
Right now I am building a LR-308/AR-10 and am looking at a 20" bull (.936) barrel. Which twist rate would be best for M118 175 grain ammo and some 220 Grain sub sonic with a suppressor? 1 in 8.5 or would 1 in 11 work fine? And are the 308b chambers able to use the M118 round?
Thanks,
Brian KE4CXP |
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Post by GLSHOOTER on Mar 30, 2015 5:21:13 GMT -8
I can't imagine why it would not chamber and run with those.
As for subs I have no experience in that one. I always figure rule of thumb on the big boys is to go fast twist so the 1:8 but I also fret that the fast twist will degrade the main bullet somewhat. In this one I would wander over to Snipers Hide and ask how the two twist do on subs when paired with super later.
Greg
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Post by asfaraslogic on Apr 3, 2015 17:22:22 GMT -8
I was wondering so hard about this... i went with 11, but i have reservations. I MAYBE SHOULD ASK TO CHANGE IT QUIK?
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Post by GLSHOOTER on Apr 3, 2015 19:06:21 GMT -8
I was wondering so hard about this... i went with 11, but i have reservations. I MAYBE SHOULD ASK TO CHANGE IT QUIK? What did the Hide guys say? Greg |
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Post by asfaraslogic on Apr 4, 2015 14:39:05 GMT -8
They talk about 10 to 1 alot for some reason bhw seem to be all alone with their twist rates...
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Post by GLSHOOTER on Apr 4, 2015 14:42:25 GMT -8
They talk about 10 to 1 alot for some reason bhw seem to be all alone with their twist rates... Maybe because the polygon rifling works at 1:11 very well. Did they say 1:10 for subs? Greg |
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Post by asfaraslogic on Apr 4, 2015 14:59:28 GMT -8
That makes more sense. I wanted to shoot heavy and distances... but 11 to 1 seems the compromise. I can shoot medium weight I guess.
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Post by GLSHOOTER on Apr 5, 2015 6:17:58 GMT -8
That makes more sense. I wanted to shoot heavy and distances... but 11 to 1 seems the compromise. I can shoot medium weight I guess. Have a little faith. I think you will be surprised on what you can shoot on the heavy end. Greg |
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ocd
Junior Member
Posts: 17 
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Post by ocd on Apr 13, 2015 8:39:54 GMT -8
Right now I am building a LR-308/AR-10 and am looking at a 20" bull (.936) barrel. Which twist rate would be best for M118 175 grain ammo and some 220 Grain sub sonic with a suppressor? 1 in 8.5 or would 1 in 11 work fine? And are the 308b chambers able to use the M118 round?
Thanks,
Brian KE4CXP Find a twist rate calculator and enter the bullet info plus your estimated muzzle velocity and twist rate. I enter 1050fps-1080fps. That'll give you an ide of what you need. I load subs for 300blk. For subs you need a faster twist to achieve the proper rpm with the slower velocity. Otherwise they'll be keyholing and you might have a baffle strike in your suppressor. (ask me how I know). JBM ballistics has a stability calculator, www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi |
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Post by jla1911a1 on Dec 13, 2015 13:42:25 GMT -8
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