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barrel twist rate, ar15 ?

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michiganman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote michiganman Quote  Post ReplyReply Direct Link To This Post Posted: February/24/2011 at 01:33
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
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote steve56 Quote  Post ReplyReply Direct Link To This Post Posted: July/06/2011 at 23:20
ya,thosereal  light bullets in a 06 with a 1 in 10 are all over
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: July/08/2011 at 15:33
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. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: July/08/2011 at 16:04
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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Urimaginaryfrnd Quote  Post ReplyReply Direct Link To This Post Posted: July/08/2011 at 21:27
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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cheaptrick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 09:29
Originally posted by supertool73 supertool73 wrote:

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

Good deal! Thanks! 
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koshkin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 13:33
Originally posted by cheaptrick cheaptrick wrote:

Originally posted by supertool73 supertool73 wrote:

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

Good deal! Thanks! 

I bought a box of those, but have not tried them yet.  My AR likes 77gr SMKs and it seems that the hotter I run them, the better it likes them, so with that bullet I stick to NATO brass and run them at NATO pressures.

It did not like any of the 68, 69 and 75 grain bullets I have tried to date, but for some odd reson it liked the new Hornady 53gr boattail V-Max.  Go figure.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shooter07 Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 15:52
My BCM middy (1-7) loves the hornady 75's. The 1-7 twist rate will generally keep tighter groups with the heavier bullets, from what i've seen. Now with that being said i've had great results with 223 ultra max 55 grainers. I've got plenty of 5.56 Winchester white box (Korean made) because it's cheap and shoots very well out of my rifle. Now get the exact same ammo made in America and it's horrible, which pains me to say.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 17:34
Originally posted by shooter07 shooter07 wrote:

My BCM middy (1-7) loves the hornady 75's. The 1-7 twist rate will generally keep tighter groups with the heavier bullets, from what i've seen. Now with that being said i've had great results with 223 ultra max 55 grainers. I've got plenty of 5.56 Winchester white box (Korean made) because it's cheap and shoots very well out of my rifle. Now get the exact same ammo made in America and it's horrible, which pains me to say.



That's what I'm running, Brother. A Bravo Middy. 
Not sure why in the world I haven't tried the heavier bullets in her. I think that the 75gr. ?? TAP ammo sucked so bad at 100 yards, that I gave up. Terrible, terrible groups with that TAP. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shooter07 Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 20:58
Originally posted by cheaptrick cheaptrick wrote:

Originally posted by shooter07 shooter07 wrote:

My BCM middy (1-7) loves the hornady 75's. The 1-7 twist rate will generally keep tighter groups with the heavier bullets, from what i've seen. Now with that being said i've had great results with 223 ultra max 55 grainers. I've got plenty of 5.56 Winchester white box (Korean made) because it's cheap and shoots very well out of my rifle. Now get the exact same ammo made in America and it's horrible, which pains me to say.



That's what I'm running, Brother. A Bravo Middy. 
Not sure why in the world I haven't tried the heavier bullets in her. I think that the 75gr. ?? TAP ammo sucked so bad at 100 yards, that I gave up. Terrible, terrible groups with that TAP. 
 
I wish i had a crapload of cash to go out and buy about 100 different types 223/556 and really pinpoint which over the counter loads do the best. Big Grin I haven't found anything that will go better than 1MOA consistantly at 100. Being that it's a chrome lined barrel, you sacrifice a little accuracy for barrel life, which can be argued both ways. Personally if i'm shooting MOA or close to that with a "battle" rifle that likely never see's battle, i can't complain to much.
 
I'm currently in the market for a 1-8 twist stainless BCM light model. They've been getting rave reviews. For the craftsmanship and price, you simply cannot beat BCM. And they've got tremendous CS as im sure you know.


Edited by shooter07 - July/09/2011 at 20:59
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alan Robertson Quote  Post ReplyReply Direct Link To This Post Posted: July/09/2011 at 23:08
The long- range AR shooters around here go with 1:8 or 1:7.5 and the heaviest bullets they can find.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: July/10/2011 at 08:10
What powder you using with the 75gr that gives the most accuracy, ST? 

  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: July/10/2011 at 23:19
24.5 grains varget in winchester brass.  CCI small rifle.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jjrgr21 Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 00:06
hey koshkin, how do those 53's do past 300? i've been using 68's on groundhogs, but they make it back to their holes sometimes.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 07:16
Originally posted by supertool73 supertool73 wrote:

24.5 grains varget in winchester brass.  CCI small rifle.

I was so hoping you'd say Varget! Wink 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 08:38
Very few ar barrels are target quality, unless you have one installed by  a smith. Combinations of of nato chambers, Wilde, and 223 chambers and the wide variety of combinations of loads gives interesting results. Sometimes blc2 gives better accuracy, than varget, sometimes Tac. Faster twists sometimes shoot 75 amax, sometimes they prefer more tangent ogives and deeper seating. My experience shows that a barrel that likes 68 gr H. match will shoot 69 gr smk, but rarely 75 gr amax . 77 smk  shoot sometimes, but at that cost you can shoot 308. 60 gr vmax seem to have good all around performance, but rarely stellar. currently I have a rra operator nato chambeer that shoots pmc green tip into 1/2 inch. Figure that one out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 08:47
Getting reliable expansion from 223 is sometimes difficult when using bthp, they are especially dependant on velocity. At longer ranges they tend to pencil through rockchucks, 69 smk being the best in my experience. Usually 50 gr. vmax has worked best for me as the bc of this class is about the same and the extra velocity pays off. Currenty using a Krieger barreled LAR Grizzly target ar with 68 gr H. match, shooting as good as any bolt gun I've had. Hope to test the 24 inch barrel this summer on high country chucks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 09:19
That is the problem with my 16" AR and the 75s, I am only getting like 2550 velocity.  It is very accurate, but very slow.  But it does not shoot the lighter bullets for crap, so I am kind of stuck with it. 

In the future, I think I am going to stick with the 1-9" twist barrels so I can just run the 55s and 60s.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BeltFed Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 10:16
Originally posted by supertool73 supertool73 wrote:

That is the problem with my 16" AR and the 75s, I am only getting like 2550 velocity.  It is very accurate, but very slow.  But it does not shoot the lighter bullets for crap, so I am kind of stuck with it. 

In the future, I think I am going to stick with the 1-9" twist barrels so I can just run the 55s and 60s.   
Kind of the same conclusion I came to, too.
 
I sat down with some calipers and measured the overall lengths and bearing surfaces of the 77gr SMK and 75gr Horn. bthp. While the SMK was longer and should have better balistic coefficient, the Horn. has a longer bearing surface and should have a little edge on stability and runout in the barrel. The differences don't seem great enough to really make that much of a difference, and maybe there won't be if I can just find that magic load. I know the .30cal. 175 SMK and 178 A-Max have similar performance in one rifle, with a slight edge to the SMK. I'm just hoping to get the same results with the 75 and 77gr pills.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jjrgr21 Quote  Post ReplyReply Direct Link To This Post Posted: July/11/2011 at 10:17
have you tried the 68-69, mine shoots them very well. it shoots the 75's pretty good, and with 24.2 of V and cci 400's, i get about 2700fps.

they both kill the hell out of ground hogs, it guts them, but they make it back to the hole sometimes. so i thought i'd go a bit lighter.
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