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 1/9 twist vs 1/7
huggytree  [Member]
1/14/2012 12:57:51 PM
i sold my old colt AR w/ 1/7 twist....i had a potential buyer who wanted a 1/9 ....he said it was for heavier bullets

now i have a Ruger SR556 and i see its 1/9 twist.....then i just read an article about the SW AR's being 1/8 twist

what bullet weight is best for my 1/9 twist barrel and what does it really mean? i assume the rifling twists 9x ?

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tstanfield12  [Team Member]
1/14/2012 1:02:48 PM
Although most barrels are different a 1/9 twist generally shoots best with 55-62 grain rounds although quite a few will shoot the heavier stuff just fine...

If you want to shoot anything heavier just test it out at the range first to see how it performs.

RedFalconBill  [Team Member]
1/14/2012 1:05:36 PM

Originally Posted By huggytree:
i sold my old colt AR w/ 1/7 twist....i had a potential buyer who wanted a 1/9 ....he said it was for heavier bullets

now i have a Ruger SR556 and i see its 1/9 twist.....then i just read an article about the SW AR's being 1/8 twist

what bullet weight is best for my 1/9 twist barrel and what does it really mean? i assume the rifling twists 9x ?


1) Welcome to the site.

2) No, it means that the rifling completes one turn in nine inches, not that the rifling completes nine turns in the barrel.

3) Did you read the FAQ's?

AR-15 » Ammunition » AR15 Ammo Forum FAQ #7
PFC  [Member]
1/14/2012 1:09:40 PM
Every 1x9” barrel I have had did just fine with 69gr SMKs.
hotbiggun42  [Team Member]
1/14/2012 1:28:47 PM
Your buyer was misinformed. 1/9 is never a better option than 1/7
TheMercenary  [Team Member]
1/14/2012 1:54:48 PM
Originally Posted By hotbiggun42:
Your buyer was misinformed. 1/9 is never a better option than 1/7


+1

All the 1x9's I have had would not even shoot 62gr as well as a 1x7.... The 1x9 will work best with a 55gr projectile

My 1x7's will shoot anything 55gr up to my 77gr SMK's



Matt_B  [Team Member]
1/14/2012 1:59:24 PM
This is covered in a FAQ here.

What bullet weight can I shoot in my <1/9, 1/8> rifle?
SYSTEM  
1/14/2012 2:00:22 PM
Topic Moved
heavyduty  [Team Member]
1/14/2012 3:27:00 PM
Originally Posted By hotbiggun42:
Your buyer was misinformed. 1/9 is never a better option than 1/7


Never is a very long time - if I were shooting 45g HPs exclusively I would much prefer a 1:9 over a 1:7.

Most people IMO are best served with a 1:7.

DanTSX  [Team Member]
1/14/2012 6:07:52 PM
Try a full range of bullets, at various distances (50, 100, 150, 200, 200+) with your barrel before you go swapping.

You may very well be surprised at what stabilizes in your barrels.

So far, I've honestly been very impressed with 1/9 barrels the most for accuracy with cheap ammo. 1/8 stainless seems to really shine with the heavier stuff, but each barrel is different with the heavier loads.

foursixty  [Member]
1/15/2012 3:53:50 AM
Originally Posted By DanTSX:
Try a full range of bullets, at various distances (50, 100, 150, 200, 200+) with your barrel before you go swapping.

You may very well be surprised at what stabilizes in your barrels.

So far, I've honestly been very impressed with 1/9 barrels the most for accuracy with cheap ammo. 1/8 stainless seems to really shine with the heavier stuff, but each barrel is different with the heavier loads.



+1

Most nowadays' want the 1/7 because it's whats hot these days. I can't afford to consistently feed a 1/7 barrel the high-dollar-ass ammo to get any real world benefit.

A 1/9 twist barrel will shoot a broad range of ammo just like 1/7 will. Only difference is a 1/9 will shoot from light to medium weight bullets best, and the 1/7 will usually prefer the medium to heavier weight bullets (I think it's actually a little more dependent on bullet length). Just because the 1/7 is currently all the rage does not make a quality 1/9 a dinosaur.

I agree with DanTSX. The 1/9's really seem to get you better results with the cheaper 55-62gr bullets than most 1/7's. Of course this is just a personal observation and not concrete. Barrels of all twists will vary widely with the ammunition they prefer. I refuse to believe that a 1/7 is superior because it's not, sorry. It will be superior for some and not so much for others. Depends on what the guns primary purpose is as to which will be best for you. If I could afford to shoot a bunch of 69-80 grainer's I too would probably opt for a 1/7.

I actually want to try a .223 Wylde chamber with a 1/8 twist. I hear they are supposed to be very versatile, although I have no firsthand knowledge to verify that.
InfiniteGrim  [Team Member]
1/15/2012 4:06:35 AM
Originally Posted By PFC:
Every 1x9” barrel I have had did just fine with 69gr SMKs.


Mine shoots nicely with 75gr rounds at 50 yards. Havent tried farther then that.
Reticle  [Team Member]
1/15/2012 12:57:47 PM
I had a 1/9 barrel that i sold recently that was alot more accurate than my 1/7.
InfiniteGrim  [Team Member]
1/15/2012 5:02:17 PM
Originally Posted By Reticle:
I had a 1/9 barrel that i sold recently that was alot more accurate than my 1/7.


Just so noone gets confused its not the twist that's making more accurrate
DanTSX  [Team Member]
1/15/2012 6:14:14 PM
Originally Posted By foursixty:
Originally Posted By DanTSX:
Try a full range of bullets, at various distances (50, 100, 150, 200, 200+) with your barrel before you go swapping.

You may very well be surprised at what stabilizes in your barrels.

So far, I've honestly been very impressed with 1/9 barrels the most for accuracy with cheap ammo. 1/8 stainless seems to really shine with the heavier stuff, but each barrel is different with the heavier loads.




I actually want to try a .223 Wylde chamber with a 1/8 twist. I hear they are supposed to be very versatile, although I have no firsthand knowledge to verify that.


.223 Wylde will eliminate any issues with accuracy and erosion when switching between .223REM and true 5.56NATO rounds.

I had it in my 1:8 twist RRA national match rifle and it was VERY accurate. Of course, some rounds were still duds coming out of it. Prvi 69gr as a notable example shot like 55gr XM193. The 75 gr and 77gr hornady and black hills loadings would leave you thinking that some sniper in the woods was shooting your target for you.
LonghunterCO  [Team Member]
1/16/2012 5:54:02 PM
Originally Posted By InfiniteGrim:
Originally Posted By PFC:
Every 1x9” barrel I have had did just fine with 69gr SMKs.


Mine shoots nicely with 75gr rounds at 50 yards. Havent tried farther then that.


I have seen some funky post of keyholeing at close range but my experience is that you have to get out 75-100yds to see if its stabilizing.
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