View Full Version : Twist rate for barrels.

12-23-2012, 08:40 AM
Was looking around to get my first AR and the barrel twist rate is really making my decision very hard. I have heard that a 1:7 twist rate will not shoot cheep 55gr ammo accurate. Looking for some feedback for more experienced AR people. Thanks a lot.

12-24-2012, 02:06 PM
Think of this as a mechanics question. You need to look at twist rate, barrel length, and the rounds you plan to shoot. heavier rounds and shorter barrels typically need a higher twist rate to compensate and keep the round stable in flight, since a barrel shorter than 20" means you don't get a full powder burn before a typical round leaves the muzzle. There are also fast burning powders used for carbines to help with that as well. You just need to pick the barrel length you want, then decide the type of ammo you plan to use in it, and get the proper twist rate based on those two decisions.

I have a couple of 9:1 7" barrel DPMS kitty kat ARs that you wouldn't want to use a heavier round with, for example. They just can't get a good enough spin on a heavy round with only 7" of barrel to travel. With a 20" barrel, it's a completely different story, and a high twist rate would slow the round down, decreasing range and muzzle velocity/energy as a result..

there's lots of info on this stuff around the net though and I'm not really an expert.

12-25-2012, 03:35 PM
Thanks for the input. That's what I have pretty much read also. Just have gotten scared about the 1:7 not shooting cheep ammo well. The reason I keep talking about the 1:7 is my favorite AR I have been looking at is the Sig M400 in FDE. I just love that complete FDE look, but I might have to pass on the whole thing FDE so I can get a better shooting AR I suppose.

12-25-2012, 08:36 PM
swap barrels, or look at some other quality ARs like CMMG, Daniel Defense, BCM, or Ruger's piston operated AR, the SR556.

Personally, I'm looking around for a BCM Gunfighter Select Carbine. I'd love to have one. Just need to find out the cost and where to get one.