AR15.Com Archives
 best barrel twist rate
lbw1230  [Member]
3/3/2011 9:31:58 PM
I am looking at buying my first AR-15 in the coming months. I would like either an A2 style 20 inch barrel or a midlength carbine. While looking around, I see many different barrel twist rates. I know that the military uses a 1x7 twist for their barrels, but is this the best choice? My uses for the rifle will mostly be a plinker with 55 grain ammo. If the AR is accurate enough, I may use it to shoot prairie dogs out to about 350 yards. If I do buy a rifle with a 1x7 twist and a 16 inch barrel, what kind of accuracy can i be expecting with a scope and quality ammo at 100 yards?

Thanks in advance,

lbw
dcs12345  [Team Member]
3/3/2011 9:39:15 PM
As far as accuracy goes, we would need to know what quality of barrel you are going with. Then of course every barrel is a little different. My 16" barrels can do around 1.5-2 depending on ammo, with a scope.
lbw1230  [Member]
3/3/2011 9:41:55 PM
I will probably be going with a Del-ton kit, mostly because I will be turning 18 shortly and money is pretty tight. I also know that they have a good reputation for quality. Otherwise, I will be buying a DPMS (I do not know what model) from a friend.
tstanfield12  [Team Member]
3/3/2011 10:11:33 PM
1/7 or 1/8 can shoot pretty much anything out there.

You will see better accuracy normally from a stainless barrel but chrome lined can also shoot very well.
458winmag  [Team Member]
3/3/2011 10:14:55 PM
If you want more information on this there's about two dozen such posts this year alone
DansFlash  [Team Member]
3/3/2011 10:17:33 PM
1x9 or a 1x7 either one. A general "rule of thumb" is that lighter grain bullets stabilize better with the 1x9 and the heavier grain bullets need the 1x7. I only own 1x7's and 55 grain bullets shoot just fine out of them. Personally I'd only get the 1x7 so you can shoot some 69 or 77 grain bullets if you wanted to.
anesvick  [Member]
3/3/2011 10:25:18 PM
Unless your shooting 40 or 45 grain varmint bullets, get a 1x7, there's no reason not to.
jlow  [Member]
3/3/2011 10:27:45 PM
The 1:7 is usually the best choice. The only other problem I have run across with this twist rate is if you want to run a 22LR conversion - the higher twist rate is a bit too much for the small rounds.
86HMMWV  [Team Member]
3/3/2011 10:29:07 PM
Personal preference.
diaz_aa  [Team Member]
3/3/2011 10:41:58 PM
It is all up to your ammo . My 1:9, 1:7, 1:8 all shoot pretty much the same. I shoot 55 gr. brass cased - insert name here-. I cannot tell a difference, seriously.
streetstar  [Member]
3/4/2011 11:45:03 AM
Defensive oriented and combat rifles almost universally have gone to 1:7 twist ––––––- at the other end of the spectrum –– if you want to go to prairie dog town , a lot of the .223 chambered bolt rifles (apples to oranges i know) will be 1:14 twist , which is not a common AR twist rate. The old M-16's which were designed with 55 grain pills in mind are 1:12 twist (this is also a very rare twist rate for a modern AR)

That leaves 1:9 or 1:7 for DelTon –––––––– either will do what you need . If i were to ever go lighter than 55 , i'd rather have the 1:9, but those would be dedictaed varmint bullets for the most part

Since this is your first build , i wouldn't sweat it too much, just get whats available, then shoot it and love it. When i got my first AR , i knew very little about the platform other than what i learned in the Army many years previously. I just bought a general purpose carbine in 5.56 , then later, when i found out i preferred making tiny groups in paper at 100 yards, i built a .223 chambered rifle with a heavy barrel (both of these were 1:9 twist) ––––- then later still, i decided i wanted to try a few urban rifle and carbine courses and purchased a 1:7 twist M4 style rifle (6920)
wagonwheel1  [Member]
3/4/2011 6:28:09 PM
Double tap on this,

Since this is only your first it really doesn't matter which one you go with, because your

second and third buys will be when you start experimenting with different combinations.

Everyone needs a 1x7 and a 1x9!!!
pun  [Member]
3/4/2011 8:09:00 PM
I have 1x7s they will shoot 50 to 77 grain excellent.
survivorman  [Team Member]
3/4/2011 8:12:44 PM
1/7.......ammo choices are greater 55gr and up will shoot just fine
Stegadeth  [Team Member]
3/4/2011 11:19:58 PM
With quality, modern ammo, there is nothing wrong with shooting even 40 grain bullets out of a 1:7 twist barrel. Check on BS Busters 002 from Molon, scroll down some in the first post and get an education from one of Arfcom's best minds.
JarHeadTim  [Member]
3/5/2011 11:47:05 AM
Originally Posted By DansFlash:
1x9 or a 1x7 either one. A general "rule of thumb" is that lighter grain bullets stabilize better with the 1x9 and the heavier grain bullets need the 1x7. I only own 1x7's and 55 grain bullets shoot just fine out of them. Personally I'd only get the 1x7 so you can shoot some 69 or 77 grain bullets if you wanted to.


+1
DanTSX  [Team Member]
3/5/2011 11:52:32 AM

Originally Posted By DansFlash:
1x9 or a 1x7 either one. A general "rule of thumb" is that lighter grain bullets stabilize better with the 1x9 and the heavier grain bullets need the 1x7. I only own 1x7's and 55 grain bullets shoot just fine out of them. Personally I'd only get the 1x7 so you can shoot some 69 or 77 grain bullets if you wanted to.

I agree that the 1/9 stabilizes lighter bullets better. Honestly, the most accurate carbines that I've shot in the past several years have been 1/9 twist stags and S&W's with the slightly softer barrel. My own 1/7 barrel did not impress with lighter ammo, but wakes up a bit on the heavier stuff.


Unless you are shooting for score or hunting, I wouldn't let the twist drive you too much. For those purposes, barrel material (i.e. stainless match barrels) are going to give you the edge that you are looking for. I'm thinking that most folks go to 1/7 these days because we tend to follow whatever is "mil-spec" and for good reason if we are looking for good, general purpose carbines, where precision accuracy is secondary to reliability and commonality.
Orion  [Member]
3/6/2011 11:50:52 AM
As I am looking for an upper as well, if you have your main accuracy ammo being Black Hills 52gr., is it safe to conclude that a 1:9 twist barrel would be better than a 1:7 barrel? I know that a stainless barrel in 1:8 twist would be best.
beltfed74  [Member]
3/6/2011 12:09:25 PM
If I was going to shoot nothing but 55-62gr Id be perfectly happy with a 1/9 twist. Which I do, thats all I shoot is that range. Plus it would put you on the safe side if you use a lighter jacket varmint round. Even though I dont think you can get a .223 fast enough to smoke the jacket off.
BRONZ  [Team Member]
3/6/2011 12:17:19 PM
1/7 does everything well.
DanielW  [Team Member]
3/6/2011 12:23:51 PM
I have a Sabre Defence SS that has a 1/8 twist. It is very accurate but I only shoot the lighter stuff.