AR-10 twist rate ?

dirtgimp

dirtgimp

New member


i need to find an upper for my dpms AR-10 lower.

i have never shot a .308 before so i don't know what

twist rate to look for or order.

i woould like togo with an 18" flat top either gas or piston

drive. any help or advice you could give would be great thanks.
 
An 18" AR10 style carbine is not much of a "Long Range" rifle, mainly because you are stuck with loading any round to the magazine OAL. I would send you the opposite direction and go 12 or 13 twist, that way you can shoot the 110 and 125 grain bullets. You will gain more FPS with less twist and not have extraction problems. You will still be able to enjoy the 150's and 165's with adequate 500 yard accuracy and thumping power also.
 
.308
1:8 For bullets heavier than 220gr.
1:10 For bullets up to 220 gr.
1:12 For bullets up to 170 gr.
1:14 For bullets up to 168 gr.
1:15 For bullets up to 150 gr.

If I was going with the 18" barrel, I'd pick 1:12 personally.
 
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The only problem a heavy twist can cause is bullets coming apart from the
rpm developed in a light jacket. Not generally a problem in a round as large
as a .308. You won't be able to document a difference in bullet speed as it
isn't enough to rival the difference in one barrel to the next regardless of
twist. The 1:10 will let you shoot everything well. The slower twists won't.
 
I use the 1 in 12 twist. I shoot 150's and 165's only so the 1-12 works great for me....I have great accuracy well out past 500 yards.
 
11.25 is what armalite used for years in the ar10's and ar10t's. You could
easily go with a 1:10 but I don't know if you can magazine feed a bullet longer
than a 190, you would have to check on the loaded oal. Also you can't load
as hot as a bolt gun and the big 220's don't have any advantage for long
range out of an ar.
 
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