Is 1:7 too fast? - Page 2


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Old 12-27-2011, 02:51 AM   #11
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No. 1x9 is perfect for your shooting needs.
thanks tikka, i thought so, but was unsure after all the different twists were mentioned. so if i wanted to shoot heavier bullets then use the 1-7 twist barrel?


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Old 12-27-2011, 03:08 AM   #12
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55,

The 1:9 will handle up to 69 grain bullets very well. What you need to also consider the 55 gr. bullets which the 1:9 will shoot very well also are less expensive normally than the other weights and are in more supply regarding availability! Still I think the 1:9 is the way to fly all around vs. the 1:7! Not that the 1:7 is a bad twist rate.

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Old 12-27-2011, 03:17 AM   #13
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55,

The 1:9 will handle up to 69 grain bullets very well. What you need to also consider the 55 gr. bullets which the 1:9 will shoot very well also are less expensive normally than the other weights and are in more supply regarding availability! Still I think the 1:9 is the way to fly all around vs. the 1:7! Not that the 1:7 is a bad twist rate.

03
thanks for the information 03. i pretty much shoot the 55gr weight bullets, but it nice to know that i could go a little heavier if i wanted to or found a really good deal on a heavier bullet.
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Old 12-27-2011, 06:09 AM   #14
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Anyone other than me remember that when the ar first came out it was a 1:17 twist? (Just marveling about how unstable that'd be) anyway regardless of bullet weights the tighter the twist the more penetrating power and stability the round will have, conversely the less twist will give the round more of a chance to tumble and fragment when it hits flesh doing more damage and cutting down on overpenetration. There is however a considerable drop in longer range stability. Just try ro reason with yourself based on this and then worry about what type of bullet weight you're going to use. Having your heart set on 55gr fmjs seems a bit odd. Id probably go for a 1:11 because I use my ar for home def and varmint hunting under 200m so I'm looking for a rou d that imparts all energy in the body and doesn't exit. However if you're just target shooting, or using it for say 400-500m go with something like a 1:7. Also (I know I'm being completely obvious here) but if you put a heavy say 65gr roung through a faster twist rate you'll literally be stripping out the rifling with each shot killing your barrel making you to go to a less aggressive twist rate. On the other hand a light round going out of a low twist rate barrel won't be as stable as a heavier round out of the same barrel, it also won't damage the barrel, but longer ranges could prove difficult.

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Old 12-27-2011, 02:49 PM   #15
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Don't know about early prototypes but by the time the AR15 went to Vietnam its twist rate was 1:14" and as you said it did have a reputation for tumbling and fragmenting in the enemy.

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Old 12-27-2011, 04:13 PM   #16
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55,

The 1:9 will handle up to 69 grain bullets very well. What you need to also consider the 55 gr. bullets which the 1:9 will shoot very well also are less expensive normally than the other weights and are in more supply regarding availability! Still I think the 1:9 is the way to fly all around vs. the 1:7! Not that the 1:7 is a bad twist rate.

03

+1

I would like to add that with today's ammo selections, I'm really surprised that more builders/manufactureres aren't going with the 1x8, like the S&W. 1x8 really seems to be where's its at, unless your shooting lw varmint rounds or super long or tracer ammo.
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Old 12-27-2011, 04:18 PM   #17
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Don't know about early prototypes but by the time the AR15 went to Vietnam its twist rate was 1:14" and as you said it did have a reputation for tumbling and fragmenting in the enemy.
Man Quentin you really had me stumped there for a minute and I had to go do some research. Only the very earliest M16's (Models 601 & 602) in the early 1960's, that were bought mostly by the Air Force, had the 1/14 twist barrels. I never knew this, but I'm never too old to learn something.

When the M16A1 upgrade arrived with things like the bolt forward assist, the twist rate had been increased to 1/12 and stayed that way until the M16A2 was adopted with the current 1/7 twist.
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Old 12-27-2011, 06:06 PM   #18
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... I had to go do some research. Only the very earliest M16's (Models 601 & 602) in the early 1960's that were bought mostly by the Air Force had the 1/14 twist barrels. I never knew this, but I'm never too old to learn something.

When the M16A1 upgrade arrived with things like the bolt forward assist, the twist rate had been increased to 1/12 and stayed that way until the M16A2 was adopted with the current 1/7 twist.
Same here, Snake, there's a lot that happened early on in AR/M16 development and we all learn something new here and there.
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Old 12-27-2011, 10:42 PM   #19
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Default AR 15 Twist & Ammo

I am a Gunsmith. Now retired. I own a Wilson AR made some time ago. Wilson guarantees 1/2 MOA(?) with Factory 69Grain Ammo I believe. My version is 1:9 if I remember correctly.

I believe the Spec Op types may be shooting 69G or I've read 77Grain. That is just what I've read and I don't remember any discusion of twist. I've recently read that some special HP ammo has been Ordered & Authorized for use by Spec Ops. Possibly to become universal to the Army in the future.

I believe the Globe & Anchor boys have an entirely different take on ammo.

Since I am Ex Army, I follow them mostly.

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Old 12-28-2011, 02:17 AM   #20
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The SF guys used match grade stuff when I was in. They gave us a small lot of it as we began to run low. It was heavier than our green tip but I don't remember what grain.

If NATO would get w/ the times and remove ammo restraints it would sure level the playing field.

We all used 1:7



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"The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together."

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