mtgun
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Post by mtgun on Nov 17, 2011 12:38:58 GMT -8
I am ready to order a 22" 243Lbc barrel, but am concerned about the twist rate. When I called I was told 1 in 10 was the best for all bullets (58 to 108). I would think a minimum of 1 in 9 would be needed to stabilize 100+gr bullets. Am I wrong?
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Post by guncollector on Nov 17, 2011 15:18:04 GMT -8
I am ready to order a 22" 243Lbc barrel, but am concerned about the twist rate. When I called I was told 1 in 10 was the best for all bullets (58 to 108). I would think a minimum of 1 in 9 would be needed to stabilize 100+gr bullets. Am I wrong? I agree that a 1 in 9 twist rate would be better for the heavier bullets. There is a thread in the AR rifle section about 243lbc barrels with a 1 in 9 twist. Supposedly it is available by special order.
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mtgun
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Post by mtgun on Nov 17, 2011 16:23:51 GMT -8
I read that thread before i called. I also see a lot of 6rat and 6mmar are 1 in 8 twist.
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mtgun
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Post by mtgun on Nov 17, 2011 18:05:36 GMT -8
Can 105 bergers or amaxes be loaded magazine length? What about 107 matchkings?
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Deleted
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Post by Deleted on Nov 17, 2011 18:13:02 GMT -8
This is what I can tell you from experience: 1:7 or 1.7.5 Berger 115 gr VLD DTAC 115gr VLD (D. Tubb's one)
1:8 Hornady v-Max 105gr Berger VLD 105 and 115gr. SMK 107 gr
The above are extremely high BC slender bullets.
1:9 SGK 100gr. Berger 95 gr VLD SMK 100 gr. SPT/SBT Barnes 80gr TTSX (solid)
1:10 H. V-max 87gr (very nice bullet .. G1 =0.4) 90gr SGK Berger 88 gr and 89gr. SGK 80gr FMJ, BTHP Many other spitzer 70 to 90gr. (no 90gr VLDs or match)
Any below can go slower twist for varmint of course.
The 115grainers on the top might work in some 1:8 long barrels but you need to put some speed that this round cannot produce.
You do not want over spinning but for sure you do not want something too slow. Angular momentum also wears out at longer distances and might show. The best thing and also what I do is to choose the purpose, choose the bullets and follow the manufacturer's recommendation.
Based on this casing I see very little need for average purpose for anything faster than 1:9 and even 1:10 has many very efficient bullets for hunting and target fun.
I hope this helps.
Cheers. E.
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Post by guncollector on Nov 18, 2011 1:18:10 GMT -8
1shot, Very good info on twist rates. I recall reading a comment from Carl, BHW owner, that polygonal barrels will have a higher muzzle velocity than conventional rifled barrels. As a result a slower twist rate can be used. I think the example Carl used was if a particular bullet requires a 1 in 8 twist with conventional rifling a 1 in 9 twist would be required with a polygonal rifled barrel. I remember reading a thread where some of the BHW prostaffers were testing the 6mm 1 in 9 twist barrels. They were getting very good results with the heavier 6mm bullets.
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mtgun
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Post by mtgun on Nov 18, 2011 8:05:58 GMT -8
Thanks for the info. I would like to shoot 105- 108gr bullets with this gun. I have other guns to shoot smaller varmint bullets. I have read the ".243 1 in 9 twist is a winner" post (and anything else on the web that mentions 243lbc) where they shot 105 amaxs and 58 gr vmaxs with the 1 in 9. That is why I was concerned when he said 1 in 10 would be best. Looks like I will have to call and talk with Andy again and try to get a 1 in 9 or faster.
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mtgun
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Post by mtgun on Nov 18, 2011 8:09:31 GMT -8
What is the largest bullet that can be loaded magazine length. I am asuming 105 berger and amax. what about Berger 108gr Match Target(non VLD)?
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Deleted
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Post by Deleted on Nov 18, 2011 8:31:30 GMT -8
Myself and a couple other Prostaffers have been shooting the 243 LBC almost a year now, you will be good to go with the bullets you wanting to shoot out of the 1 in 10 Poly rifling
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mtgun
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Post by mtgun on Nov 18, 2011 8:43:10 GMT -8
The poly rifling makes that big of a difference?
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Deleted
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Post by Deleted on Nov 18, 2011 12:03:13 GMT -8
Yea it cuts down on the pressure, and stabilizes better then the standard rifling.
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Post by guncollector on Nov 18, 2011 16:31:55 GMT -8
WSMBUCK, I am interested in shooting 107gr. Sierra Matchkings with a 243lbc BHW barrel. Sierra says this bullet requires a 1 in 7 or 1 in 8 twist rate. Will the BHW 1 in 10 twist stabilize this bullet? Do you have any personal experience shooting the 6mm 107 gr. Matchkings with a BHW barrel in 1 in 10 twist? I want to be absolutely certain the BHW barrel will stabilize this bullet before I order mine. Thanks.
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Deleted
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Post by Deleted on Nov 18, 2011 17:19:41 GMT -8
I will try shooting some this weekend . This should be a good test
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Deleted
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Post by Deleted on Nov 18, 2011 18:17:56 GMT -8
As I said SMK stabilizes well with the 1:8 so I am not sure why the also put the 1:7. It is too much. It also looks it might work well with the 1:9 poly barrels and even slower but I have not done that before. It looks that the people here with lots of experience with different BHW barrels so we should listen to them.
I can tell you with the LW 1:9 I can shoot very well up to 100gr and 95gr VLDs that are excellent bullets. As you go higher in grain you also loose speed so then you need more twist but if your barrel is longer then it might be ok as things balance themselves out. As I said before I choose the barrel I choose what I want to do with the upper, then a good bullet or set of bullets for that purpose and then follow the manufacturers advice. Thanks.
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Deleted
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Post by Deleted on Nov 18, 2011 19:04:02 GMT -8
There is no such thing as too much stabilization of a bullet, you can over Rotate one,BUT thats in custom hand built bullets, you won't have that trouble from good quality hunting bullets. But over stabilizing one won't happen, if that was the case I would have to buy a barrel to shoot coyotes with my 58 Vmaxs then another to shoot 87 SP and one more for the 100's and 105's. Ritch can really explain this better then me,
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