Close

Results 1 to 13 of 13
  1. #1
    Colonel Degenret's Avatar
    Join Date
    Sep 2011
    Location
    Capital District
    Posts
    3,098

    Default AR15 1:7" or 1:9" twist?

    A friend is putting together his first AR build and those are his twist choices for the barrel he wants. But neither of us has a clue on why to select one over the other. The weapon will be used primarily for plinking and having fun target shooting, maybe up to 200 yards or so. So, which one is better, and why? Or does it not matter for his application? Thanks for any answers you pros can give. ~J.Murphy

    If it matters, it will be built on a CMMG upper and lower with a YHM barrel and guard.

  2. #2
    Captain
    Join Date
    Aug 2011
    Location
    Rensselaer County
    Posts
    558

    Default

    Quote Originally Posted by Degenret View Post
    A friend is putting together his first AR build and those are his twist choices for the barrel he wants. But neither of us has a clue on why to select one over the other. The weapon will be used primarily for plinking and having fun target shooting, maybe up to 200 yards or so. So, which one is better, and why? Or does it not matter for his application? Thanks for any answers you pros can give. ~J.Murphy

    If it matters, it will be built on a CMMG upper and lower with a YHM barrel and guard.
    I personally have had better accuracy results with 1:9. If I was using 55 and 62 gr cheapo range ammo I would go with 1:9. If I planned on using 69 and 77 gr match ammo I would go with a SS barrel 1:8 twist. Basically either 1:9 or 1:7 will work fine with range ammo. MY range ammo is in the 55gr and 62gr hence that is why I prefer the 1:9.....my 1;12 twist loves 40gr varmint rounds...just that stuff is expensive!

  3. #3
    Private Steve@AllstarTactical's Avatar
    Join Date
    Jul 2011
    Location
    Rochester, NY
    Posts
    39

    Default

    ^ What he said.

    Lighter Bullet = Slower Turn

    Heavier Bullet = Faster Turn
    Cogito, ergo armatum sum.

  4. #4
    Captain
    Join Date
    Nov 2010
    Location
    Pembroke, Ny
    Posts
    822

    Default

    I'm 1:8 twist I can shoot 55gr wal fart ammo or 70 gr boat tails without a problem.

  5. #5
    Private Steve@AllstarTactical's Avatar
    Join Date
    Jul 2011
    Location
    Rochester, NY
    Posts
    39

    Default

    Now that I re read the post let me explain a little further.

    What measure of accuracy are you looking for? Either twist will shoot what ever grain you send down range. If you are looking for a paper puncher then twist selection is important. If you are only ever going to plink and burn ammo then why not buy the cheaper barrel? I wouldn't go spending considerable money on a different barrel just to match twist. Shooting 55gr at 200 with a 1 in 9 or a 1 in 7 will be enough to break clays all day long.

    The 1 in 9 twist will be most conducive to you desires anyway, 55gr is about the cheapest plinking ammo you can get your hands in 223.

    We just so happen to have some barrels in house as well. What length are you looking for? What type of MD are you considering?
    Cogito, ergo armatum sum.

  6. #6
    Colonel Degenret's Avatar
    Join Date
    Sep 2011
    Location
    Capital District
    Posts
    3,098

    Default

    My friend is getting the YHM14.5" chrome lined with an attached muzzle brake seen here.
    14.5 Fluted, Pinned, Chrome Lined Barrels - $235.00 : YHM, Yankee Hill Machine Co., Inc. | Makers of High Quality Firearms, Accessories & Sound Suppressors, Makers of High Quality Firearms, Accessories & Sound Suppressors
    for $235. He wants something for fun, and to have on hand for when SHTF. What is an MD? ~J.Murphy

  7. #7
    Private
    Join Date
    Dec 2011
    Location
    Harford County Maryland/ Long Island NY
    Posts
    5

    Default

    Really. Both of my barrels are 1:7 14.5-16". When I first bought my m&p15 and knew nothing about tuning the platform, the barrel was 1:9. Shot 55-62 5.56( didnt care for .223). Haven't tried anything heavier. Grouped better than average at 100 maybe 1.5" with irons from prone. At 50 with an eotech it was 1 ragged hole a quarter could cover using 855 or 193. 223 forget about it. 2"-2 1/2 groups. Now my 1:7 I personally built from the ground up, 1 ragged whole at 100 yrds using 6 shot groups of 855 and a leop mark AR 1-4. It shoots 193 great too but 855 or 5.56 tap 75gr and up, it loves. The purpose of this post is that each rifle is different. 1:7 can handle/stabilize longer bullets and longer bullets are generally it not all the time used for extended ranges for accuracy wise. The new hype is the 1:7. I've shot carbine courses with that 1:9 m&p using 193 and with the eotech had no problem at all engaging steel man size torso targets with my eotech or my irons. What really and truley matters is how well you know the dope of the rifle, your current training, and the application it will be used for. For a target barrel look at Noveske or white oak armory(woa offers 1:8 but are tack drivers) 1:9 is fine for carbine courses but the majority of manufacturers are now leaning toward 1:7 twist for there combat barrels. Hope it helps some. Any other questions feel free to pm me or email. Tconfo@gmAil.com

  8. #8
    Captain siglover518's Avatar
    Join Date
    Oct 2011
    Location
    QUEENSBURY, warren co.
    Posts
    645

    Default

    Either or will be fine 7 will work better with heavier, longer bullets but will also shoot 55grn just fine too. Just make sure he gets the 5m1 brake, not the 5c2 flash suppressor
    god didnt make all men equal, mr colt did

  9. #9
    Head Fapper Cossey's Avatar
    Join Date
    Mar 2011
    Location
    Capital District
    Posts
    1,553

    Default

    I'm using a Daniel Defense 5.56 16" 1:7" barrel w/ Battlecomp 2.0 brake and I couldn't be happier with the results of any ammo I've used. .223 shoots perfectly fine, but the 5.56 stuff seems to be a little more accurate I think, but no conclusive results. I've only really shot 55gr. and 62gr. but plan on getting some 77gr. match ammo to really see how she shoots with that barrel.

    From what I've heard, if you get a quality 1:7" twist barrel, it'll still be accurate no matter the weight you're using. I've heard of people shooting very accurately with 45gr. out of a 1:7" twist, and heard of it going bad as well.
    Suppose the Second amendment said A well-educated electorate being necessary for self-governance in a free state, the right of the people to keep and read books shall not be infringed. Is there anyone who would suggest that means only registered voters have a right to read? - Robert Levy, Georgetown University Professor

  10. #10
    Private BCWhite13's Avatar
    Join Date
    Jan 2012
    Location
    St Lawrence
    Posts
    25

    Default

    The M4 rifle issued to the Army is 1:7, good for Carbine and general purpose. So is the Army Marksmanship Unit built SDM rifle. The standard M885 5.56mm round issued to these rifles is 62gr. Match Grade issued ammo the MK 262 is 77gr Sierra Match-King manufactured by Black Hills Ammo. 1:7 seems to work well with those type loads. The newer LWRC M6 rifle, being tested by the Army also uses a 1:7 twist rate in 5.56mm, 1:10 in 6.8mm. The chart in the below link details what twist to use for each caliber at certain weights, hope this helps.

    Welcome to Shilen Rifles, Inc.

    also Liljas link Lilja Precision Rifle Barrels - Caliber and Twist Rates

    and ATKs .223 specific chart http://le.atk.com/pdf/223_MinimumTwistRates.pdf
    I'LL KEEP MY GUNS, MY FREEDOM AND MY MONEY... YOU CAN KEEP THE CHANGE! - Anonymous

  11. #11
    Major BUCKrub91's Avatar
    Join Date
    Sep 2011
    Location
    New park, pa
    Age
    23
    Posts
    1,496

    Default

    Im going with 1:7 on my build.. everything ive read from people that TESTED 55gr ammo with 1:7 vs 1:9 twist barrels shows a very little drop in accuracy over 1:9... so I find 1:7 to be the better option because of its versatility
    ┌∩┐(◣_◢)┌∩┐

  12. #12
    General meketrefe's Avatar
    Join Date
    Jun 2010
    Location
    Logan, Utah. (Moving my business out of NY)
    Posts
    9,417

    Default

    It seems for your 'all around' purpose 1:9 could be plenty. Let me explain.

    1:9 up to 70gr bullets excluding solid coppers. will shoot 55gr/M193 , 62gr/M885 and the venerable 69gr SMK is a great one to shoot this twist. For solids it will shoot a barnes 62gr TSX w/o problems.
    1:8 up to 80gr, 70gr solids. Perfect for the 75/77grainers like Amax and SMK and popular in national match barrels.
    1:7 will stabilize anything above and larger. It is too fast for some light varmint jackets that might come apart (Jacket separation). The reason the military uses 1:7 is to stabilize some of the tracers, not a huge concern for any average practical use. You find good deals on this twist/barrels though.

    They all shoot and some shoot well. For most average use I see anyone will do. Just consider the fastest the rate the higher potential in increased pressure and loss in speed but this depends on other factors like barrel material and rifling. Also consider if you want to shoot thin jacket high speed varmint loads vs. 75/77grain or 70gr solid bullets. Most of the long bullet scenarios involve folks that reload and shoot national match barrels and 1:8 makes a good compromise for that purpose.

    90gr .223 bullets are out there but they are not efficient in the .223Rem parent case and should be reserved to the Ackley offering with VLD magazines or single feed.
    Last edited by meketrefe; 02-26-2012 at 01:24 PM.
    Giving money and power to Government is like giving whiskey and car keys to teenage boys. -- P.J. O'Rourke






  13. #13
    Private
    Join Date
    Sep 2011
    Location
    Columbia County
    Posts
    51

    Default

    1:7 is better for heavier loads, personally I wish I had 1:7 over my 1:9...

Similar Threads

  1. Myth vs. Reality; Federal "M" and "XM" Designations
    By C-mac in forum Ammunition and Reloading
    Replies: 2
    Last Post: 09-04-2011, 12:47 PM
  2. Replies: 2
    Last Post: 03-12-2011, 11:41 AM
  3. Replies: 1
    Last Post: 03-26-2010, 09:21 PM
  4. FFL in Honeoye Falls called "AR15.COM"?
    By 80sDweeb in forum General Firearms
    Replies: 8
    Last Post: 10-06-2009, 06:44 AM
  5. Replies: 0
    Last Post: 04-04-2009, 12:30 AM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •