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barrel twist rate, ar15 ?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 11:05
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can anyone help me out with barrel twist rate. I always had a hardtime under standing this area.I'm setting up my rock river lar-15 (223) for target/varmit matches ,so im getting ready to buy a new barrel. the one i have my eye on is a rock rivers varmit (bull barrel ,stainless) in ether 20 or 24"

the varmit matches shoot up to 300y and now my ? what are these twist rate's  good for and what grain bullet is best for what rate
1:8
1:9-
1:12-
 
thanks for the help
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 11:07
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1-8 80-55ish
1-9 69-50ish
1-12 55-40ish
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 11:15
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A basic explanation of barrel twist rates is, the heavier the projectile, the faster the twist you need.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 12:57
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i was told once that you can never over spin a bullet.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:01
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Originally posted by pyro6999 pyro6999 wrote:

i was told once that you can never over spin a bullet.
 
Thats B.S. 
a 30somthing gr var grenade will not shoot out of a 1-7 twist 22-250. they hit like buckshot even at 20 yards.
 
 
 


Edited by Bigdaddy0381 - February/23/2011 at 13:02
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:01
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I think urimafrnd posted a chart awahile back. would be a good sticky. if someone finds it.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:03
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I have a Rock River Varmint in both 16 and 24 inch barrels with a 1:8 twist. Mine seem to like the 69gn SMKs best. I had asked Rock River what weight worked best in the 1:8 and their reply was 68 to 72gn.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:05
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Originally posted by Bigdaddy0381 Bigdaddy0381 wrote:

Originally posted by pyro6999 pyro6999 wrote:

i was told once that you can never over spin a bullet.
 
Thats B.S. 
a 30somthing gr var grenade will not shoot out of a 1-7 twist 22-250. they hit like buckshot even at 20 yards.
 
 
 

at what speed?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:09
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Originally posted by pyro6999 pyro6999 wrote:

Originally posted by Bigdaddy0381 Bigdaddy0381 wrote:

Originally posted by pyro6999 pyro6999 wrote:

i was told once that you can never over spin a bullet.
 
Thats B.S. 
a 30somthing gr var grenade will not shoot out of a 1-7 twist 22-250. they hit like buckshot even at 20 yards.
 
 
 

at what speed?
 
all speeds, from the test and things I have done with them. Its the heat that makes them come apart something about the inside melting. I went 4 gr below min and it still did it. went 3 gr about and it still splated them.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:13
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 a 30-something grain bullet in a 22-250 is just asking for trouble.thats like shooting a 90gr bullet out of a .300mag


Edited by pyro6999 - February/23/2011 at 13:13
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:19
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I agree but you can over spen them just like you can under spin one. Like my 243 with the 105gr berger. they hit side ways.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:23
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ok im on board with you, im just saying i heard somebody say it. i didnt necessarily agree, i was just on a sight reading a little, and they said that in general the slowest twist you can use is the best (for accuracy) at least in the competition world. i usually try to match bullet weights in my guns by using the heaviest bullet with the most accuracy. in .224 45-55gr bullets have been very reliable for me.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:26
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in my .224 69gr and 70gr work best for the faster twist.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 13:29
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Originally posted by Bigdaddy0381 Bigdaddy0381 wrote:

in my .224 69gr and 70gr work best for the faster twist.

if your using a 1:7 then it should, my .22-250 is old and its got either a 1:12 or 1:14 twist which isnt good for anything that heavy.Bucky
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 14:56
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My 1-7s don't like anything under 68 very well.  At 50 yards with 62 I only get like 2 inch groups.  With 75s I can get .5 inch at 100 yards.  Its crazy the difference it makes.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 15:13
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Just to be the fly in the ointment. I tried 2 AR barrels from the same manufacturer with the same profile and both are 1 in 8" twist. One barrel likes 62 to 69gr bullits, the other will only shoot 77gr bullits worth a darn.Loco
The 1 in 9" twist barrels i've tried, shot both 55 and 62gr bullits well, but prefered the 62gr bullits. This is expected for the most part, but I was supprised by the 1 in 8" twist results. I also tried a 1 in 7" twist barrel on a Styer Aug, and it did better with 62gr bullits than one of the 1 in 8" twist barrels with 62 or 69gr bullits.Whacko
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 15:19
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I guess that goes to show us, you never really know what will work best til you try a bunch of them.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 17:46
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I agree  with the school of thought that the heavier the bullet the faster the twist rate.I do have 2 rifles that do change my logic.700 rem police in .223 ..1:9 twist that shoots best when using .75grn Hornady V max[just defies my logic]but it is dead on out to 300 yds.
 
The other rifle is my Rem 5R in .308 [11.25 twist]which will shoot .168grn & 190grn Sierra BT equally well.Loco
 
 
 


Edited by stickbow46 - February/23/2011 at 21:53
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 18:48
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I have a 1-7" twist in my AR and it has a clear preference for 77gr SMKs over all other bullets I have tried.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/23/2011 at 19:59
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- I'm under the impression that all things being equal (weight) the longer the bearing surface, the faster the twist needs to be to stabalize the bullet.
 
- FWIW, it's also known that not all barrel twist are uniform.  In example; a barrel listed as a 1-9 may avtually be a 1- 9.5 or 1- 8.75.  This probably explains why some bullets shoot out of an advertised twist while others won't.
 
- Some bullets just won't shoot in a barrel no matter what you try.  I ran thru this several years ago with an AR-15.  It wouldn't shoot a H75 BTHP (1-8) no matter what.  I was all set to rebarrel when I just happened to try some 77 SMK and presto, it grouped like a premium barrel.
 
- I have a Bushmaster with a 1-9 twist and it won't shoot much over 70 grain bullets with acceptable accuracy for target work.  For grins and giggles I tried a 80 SMK in that barrel and at 100 yards it shot an 8" group.  Went back to a 69 SMK, it was under .250".
 
HTH
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/24/2011 at 01:33
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thanks for all the input everyone. I think i made up my mind im going to go with the 1:8 bull seems like that would be the best performer for all around use. looks like with that twist it will allow me play with wide range of bullet weightBig Grin
 
one of the members asked about making a sticky on barrel twist ,i think that would be a great idea if someone can come up with something .
what i would like to see in the same sticky would be examples of why you would pick that twist for that application.
 
(example)
1:14 -would be good for bullet up to 40g
benefits- max fps
disadvantages- what ever they maybe
application-short rang target, varmit hunting or what ever
 
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/06/2011 at 23:20
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ya,thosereal  light bullets in a 06 with a 1 in 10 are all over
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/08/2011 at 15:33
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Originally posted by supertool73 supertool73 wrote:

My 1-7s don't like anything under 68 very well.  At 50 yards with 62 I only get like 2 inch groups.  With 75s I can get .5 inch at 100 yards.  Its crazy the difference it makes.  

What 75gr bullet are you shooting? My 7 twist 5.56 hates anything under 68gr. too. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/08/2011 at 16:04
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Hornady HPBT.  Much cheaper than 77 grain SMK.  You can buy them in 600 round lots for about $50 cheaper than 500 SMKs.  Midway has them on sale right now as well.  http://www.midwayusa.com/viewProduct/default.aspx?productNumber=1165559619
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/08/2011 at 21:27
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Im running 1 in 7 and 1 in 8 twist shooting 69 to 80 gr   Military uses 1 in 7 with 62 gr

BULLET WEIGHT / CALIBER / TWIST RATE CHART

Grain/Cal.172.204.224.243.257.264.277.284.308.338.358
17-209-10
2510
30912
33 12
35 12
37 VLD6
40 12
50-52 914
55 12
60 12
68-69 9,1013,14
75 9 14
80 8
85 7121212
90 710
100 1010 1214
105-107 8
120 1010 1215,16
130 10 14
140 91010
150 14
140-160 8101012,13
150-168 911,12,13
150-180 10,11,12
160 9
175 9
180 10,11,12
200 10,1110,1212,16
220 10
225 10,1212,16
240-250 101012
300 1012


Edited by Urimaginaryfrnd - July/08/2011 at 21:28
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