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-   -   Is 1:7 too fast? (http://www.firearmstalk.com/forums/f20/1-7-too-fast-54118/)

ScottA 12-25-2011 12:46 PM

Is 1:7 too fast?
 
I'm looking to do a semi-build on an AR. The Palmetto State Armory complete uppers seem to be getting a lot of good reports and are very reasonably priced. But it seems everything they are making is in a 1:7 twist. This seems pretty aggressive for a general purpose carbine.

Would you be concerned about 55 grain bullets with a 1:7 twist? Or should I really be looking for a 1:8 or 1:9?

My intent is a rifle that will be used for plinking, HD, and coyotes. I'll probably look at a different upper for varmints down the road.

EW1066 12-25-2011 01:30 PM

The only rounds that seem to have a problem with 1:7 is "varmint" rounds. I have seen video of those disintegrating about 20 yards
after leaving the barrel. As far as 55gr fmj is concerned. I shoot those out of my Daniel Defense barrel without issue. Have not had an opportunity to shoot HP yet. I guess they could self destruct since they don't have the same structural integrity as fmj bullets.

Merry Christmas

EDUB

Quentin 12-25-2011 02:01 PM

I wouldn't be worried about 55gr with a 1:7 twist but wouldn't go much lighter. Since you're thinking about a true varmint upper later, 1:7 would be ideal right now as it gives you a lot of flexibility including performance with heavier bullets.

Snakedriver 12-25-2011 03:32 PM

I've been shooting AR's longer than most here have been alive and I'll never be convinced that spinning the crap out of a light bullet will make it accurate. For that reason I went with a 1:9 twist in a new RRA recently and it is superbly accurate with 55 gr. bullets.

I go back to when I qualified expert with a M16A1 in Army Basic Training. The A1 I used was a 1:12 twist if I recall and there was only one choice of bullet and it was a 55 gr. bullet. The old M16 was deadly accurate out to 300 meters without any adjustment to the iron sights needed, even with the slower twist rate.

I probably have at least 10,000 rounds of 55 to 62 grain 5.56/.223 ammo stored up and I am positive that I'll never ever be shooting heavy bullets through my AR. I also plan on doing all my shooting at ranges of 200 yards or less.

I know it's probably available somewhere, but I've never seen any heavy weight 5.56 /.223 ammo over 62 grains for sale anywhere. I also reload this caliber, so I could obtain the heavy bullets if I wanted, but why bother. I am also fairly sure I'll never need to fire tracers or make shots in excess of 500 yards with my AR and that's the reason the .mill went with the fast 1:7 twist.

Everyone makes a big fuss about having the fast twist barrel in their AR, but it's just not necessary in my opinion for what I want to do with mine. As usual, if that's what you want, well good for you be my guest, freedom of choice is what makes this Country great.

mjkeat 12-25-2011 05:45 PM

I would stick with 1:7 as I shoot 55 and up.

Sniper03 12-25-2011 07:14 PM

Scott,

A little fast! You will not achieve peak accuracy from that combination although they will shoot fairly ok as far as just shooting. Depends on what you want out of the rifle as far as precise accuracy. I prefer the 1:9 in The tactical style AR-15. And as was stated earlier if you ever go to some of the lighter softer varmint bullets the 1:7 can spin them apart. If you were planning on shooting rounds in the mid to high 60s or heavier the 1:7 would be fine.

03

AgentTikki 12-25-2011 09:00 PM

I have put a lot of rounds, 55 grain rounds in the thousands, pmc .223, m193, xm193, and mfs russian steel case stuff. Never had a promblem with 55grainers. You'll be fine. You're not trying to get 1/2 moa groups are you? For general plinking shooting, and gunfights you're good with 55 gr fmj.

locutus 12-26-2011 10:41 PM

I use 55 and 62 grain bullets. My preference is 1-9.

Axxe55 12-26-2011 11:05 PM

i'm curious as my 16" barreled AR has a 1-9 twist, i shoot mainly 55gr. fmj ammo, would i be better off with the 1-7 twist given my ammo choice?

AgentTikki 12-27-2011 01:38 AM

Quote:

Originally Posted by axxe55 (Post 660325)
i'm curious as my 16" barreled AR has a 1-9 twist, i shoot mainly 55gr. fmj ammo, would i be better off with the 1-7 twist given my ammo choice?

No. 1x9 is perfect for your shooting needs.


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