AR15 1:10 best reload

volinTN

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Apr 10, 2011
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morristown,tn
I have built an AR15 with a 24" Olympic Arms SSMatch barrel with a 1:10 twist. I took it to the range and tried several different loads. It did not like anything in the 55 gr bullets. Seemed like my best results are going to be with a 69 gr SMK. I had some loaded with 25.3 Varget which were just OK. I had 6 old loads with 24 gr of 4895. They grouped pretty well. Does anybody with a similiar barrel have any loads that worked real well for them? I am a newbie to this site and appreciate any help you can give me.
 
I would think the 1:10 would like about any 55 grain bullet. What brands and profiles did you try? What were your group sizes? The 69 gr. SMK should be right at the edge of working in a 1:10. Glad to hear they worked out for you.

Brad
 
I tried a handload with 55 gr Blitz King and Varget. Also tried some GA arms 52 gr match loads and Bitterroot 55 gr V max factory loads. A friend gave me a handload using 55 gr V max and H335. Also tried a 75 gr load of his. None of these grouped less than 3 inches at 100 yds.
 
That's what I was thinking BigSky. With a twist like that it should run lighter bullets. Kind of crazy it likes the 69 grain SMKs, huh.

Brad
 
No surprise there, since a 1x10" is actually the ideal twist for a 69 SMK. Also, don't forget that if you've got a buttoned barrel the twist may vary 1/2" or so in either direction from the stated twist. If you happen to get one that runs a bit faster than what it's listed as, it'll handle bullets that it supposedly shouldn't. If it goes the other way (slower) it may not be able to stabilize bullets it "should". if it's handling the 69s well, run 'em!
 
BMP- I was leanin' more towards less than 50gr, I would think the barrel would max out for stability around 55, and he said he couldn't get them to shoot well.

Kevin- Good to know that's a twist for 69SMK

I know 1/7.5 is what US uses for long body bullets in their barrels. Their green tip even though it's 62gr (or was) actualy had the bearing surface of like a 77gr.

Most ARs come with 1/9 unless you realy look for a 1/8. 1/9 is great for most of the middle weights. Even 1/8 is pretty well maxed out at 80-90gr.
 
BigSkyGP,

A 1x7" is actually what the gov. uses in issue M16/M4s etc., and that's based primarily around the need to shoot the tracer rounds, which are REALLY long. The standard M855/SS109 round will do pretty well out of a 1x9", and I suspect would also probably work out of a 1x10". Haven't tried them in one, but I'm pretty sure they'd stablize.

As far as the lighter bullets go, no problem at all. I've seen the term "overstabilized" get tossed around a bit here, but technically, there's no such thing. Spinning a bullet faster than is needed to achieve stability will accentuate any problems with jacket concentricity and MAY open groups. Assuming you're using good quality bullets with decently concentric jackets, they should shoot just fine out of a faster twist. Done so in many tests, but that was using good qulity stuff to begin with, so there wasn't much to magnify in terms of error.
 
What is the best bullet for the 1/7.5 twist in a 20" barrel for the .223?

There's really no such thing, at least, based on twist alone. There's just what your particular rifle has an affinity for, and you take it from there. With a 7.5" twist, you'll be able to stabillize anything up to the 80s, 82s or thereabouts. Won't be able to use the 90s, and personally, I don't consider that to be much of a loss; they're a pain to deal with, for the most part. Anything lighter, no problem. Assuming you're using a good bullet that doesn't have jacket concentricity issues, you can shoot the little 40 grainers just as well as a much slower twist. Anything in the 50, 55, 60, etc., range, no problem.

Now the real choice of best bullet is going to come down to what you're doing with it, what are you using it for? Punching paper means a target bullet. Big game means a much more stoutly constructed hunting bullet, and varminting means something frangible. It's all about matching the bullet to the task you want to perform.
 
BigSkyGP,

A 1x7" is actually what the gov. uses in issue M16/M4s etc., and that's based primarily around the need to shoot the tracer rounds, which are REALLY long. The standard M855/SS109 round will do pretty well out of a 1x9", and I suspect would also probably work out of a 1x10". Haven't tried them in one, but I'm pretty sure they'd stablize.

As far as the lighter bullets go, no problem at all. I've seen the term "overstabilized" get tossed around a bit here, but technically, there's no such thing. Spinning a bullet faster than is needed to achieve stability will accentuate any problems with jacket concentricity and MAY open groups. Assuming you're using good quality bullets with decently concentric jackets, they should shoot just fine out of a faster twist. Done so in many tests, but that was using good qulity stuff to begin with, so there wasn't much to magnify in terms of error.

I stand corrected. I do recall being instructed that they are 1/7 twist. I could a swore I've seen the stamp say 1/7.5, I actually went and checked my A4, and two M4s, sure 'nuff 1/7.

Sorry for leading everyone on.
 
Thanks Kevin, it's just for punching paper at long range. I usually shoot bolt guns, but I am putting together a long range semi auto, just to see how it compares in a tactical match. All for fun! I just don't have alot of experience with loading .223. I've shot an M-4 alot, but not as a target rifle.
 
If you've got the twist to stabilize them, go with the heaviest bullet you can get away with, and that should be you're best choice for LR shooting. Slightly lower velocities, sure, but remember; Velocity quickly fades, but BC is forever. (thanks to German Salazar fro that one.)
 
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