Home Forums Hunting & Shooting AR and Tactical Rifles twist rate question

Will a 1&7 twist work with 55-62 grainers in my ar 556? I know its not the right rate for the lighter stuff but will it work OK? Thanks.

So far, using a variety of factory 55 FMJ as well as "bulk" handloads (bulk = minimal case prep) with 23.5 and 24.0gr of AA2230 and 55gr Hornady FMJ, I'm not seeing very nice groups in my 16" 1-7 CL bbl (4+ MOA). This is the only AR15 I've messed with, though.

I have some 55gr Hornady SPs to load and try and really want to get some 60gr Hornady SPs to try out.

To answer your question, you're supposed to be fine with 55 and above in the 1-7. The 62s should be fine, if they're decent bullets, according to all I've read.

7.5 twist stabilizes 75 gr. VLD's in my .22-204 bolt gun. I think your twist isn't the problem.

With quality, light bullets, over spin doesn't seem to be a problem.

DF

Its a 14.5" barrel. Just want to make sure it will stabilize 55 and up ammo without causing bullet destuction. Thanks.

The US military uses 1 in 7 barrels and M855 62gr bullets.

1 in 8 will stabilize 77gr. Sierras IME, others say they've had 1 in 9 barrels that would stabilize 77's but I had one that wouldn't.

Yes. I have 18" WOA 1-7 I have shot 53 to 77gr with no issues.

I've run 52s in my 6.5 twists...

as long as the bullets are not super thin varmint jackets all was fine.

Ive run 60 grainers in my vietnam clone with 1/12 twist.
(Just barely )
But my A4 1/7 seems to shoot everything i feed it just fine.
im particularly fond of the 1/12 twist for surplus 55gr.
Outstanding accuracy.
peabody

(Love them slicksides!)

62gr M855 (green tip) will go through a target at 25m sideways out of a 1 in 12 twist.

Yes they will. Did find some winchester white box 50 grainers on sale at
cabelas a few years back.
dang things shoot great in all my AR's
been shooting some 70 grainers in my 1/7 twist A4.
txs? Barnes.
Will turn a ground hog inside out at 150 yards. (Grin)
Great for deer too.
peabody

Them m855's too long for 1/12
I believe thats why the military went to 1/7 twist.
Original Vietnam rifles where 1/14 twist i thinks.
Spectacular kill wounds. They would barely stabilize the 55 fmj bullet.
Thats why i tried a 60 grainer im my 1/12
About the same. Principal.
Peabody

The old A1's maybe 1 in 14, I dunno. The Army went with 1 in 7 not to stabilize the 62gr ball but to stabilize the tracer, which (I forget the weight) is considerably longer than the standard bullet.

Self destruction of the bullets is caused more by a rough barrel and thin jackets than by too fast a twist. If a 52gr MK leaves a blue trail to the target, try Ballistic Tips.

Ya the 1/14 stabilized the 55's just fine until they were tested in artic conditions. I'm not sure if any 1/14's were issued in VN, the 1/12 twist was brought about pretty quickly.

Even a 1/9 twist will stabilize the M855 ball, like TAK said the 1/7 was for the tracers.

I've run 50 gr Federal HP's in a 1/7 with no issues and well under MOA.

The M856, the tracer round, is extremely long, which is why the 1:7 twist was needed. I believe it's 63.7gr in weight and it does not have the 10g steel penetrator, but it's very long with a hollow base to hold the pyrotechnic compound.