Preferred twist rate in AR15

Preferred Twist

  • 1 in 7"

    Votes: 52 69.3%

  • 1 in 9"

    Votes: 23 30.7%
  • Total voters
    75
who would want 1:9 over 1:7? I dont get why RRA and other manufacturers make this twist when 1:7 seems to stabilize all the good rounds out there
 
Bullet weight determines twist rate. i was fond of the old 1 in 14 for its unstable flight. It would decapitate golphers.(in the old days):dancingbanana:
 
The Stag 2T I bought is listed as 1:9 but as posted by dangertree it's closer to 1:8.5. So it should shoot the 70 grain Berger VLD bullets I bought. If not I have 64 grain as well. So 1:8.5 is my real answer :D
 
I bought a 1:9 barrel some 24 years ago, and the only bullet weight it will shoot worth a hoot is 52's. Since then, I've shot 1:8 and 1:7, and both have handled 52's, 69's and 80's fine. I still am not having any luck with Hornady 75's.

CDD
 
if you've seen all the data i have over the years you'd go 1/7- there's reams of the stuff esp transitioning twixt the 55 and the 62/70 grain weights- helmets, wet phone books what have you- and the r&d boys monkeyed with everything from the flashider to the buttstock to come up with the ar15a2/m16a2 series-you'd be foolish not to take advantage of all that research
 
t-star said:
if you've seen all the data i have over the years you'd go 1/7- there's reams of the stuff esp transitioning twixt the 55 and the 62/70 grain weights- helmets, wet phone books what have you- and the r&d boys monkeyed with everything from the flashider to the buttstock to come up with the ar15a2/m16a2 series-you'd be foolish not to take advantage of all that research
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The military adopted 1/7 to stabilize tracer rounds, not 62 gr. ball ammo. If they were only concerned with the ball ammo than their final choice may have been different.

Of course 1/7 does take care of all the heavy stuff that is becoming more popular, but then again so does 1/8.

I'm not sure that I could make a decision either way. Too many variables. I have AR's in 1/12, 1/9 and 1/7, they all have their uses for different applications.
 
Leg said:
The military adopted 1/7 to stabilize tracer rounds, not 62 gr. ball ammo. If they were only concerned with the ball ammo than their final choice may have been different.

Of course 1/7 does take care of all the heavy stuff that is becoming more popular, but then again so does 1/8.

I'm not sure that I could make a decision either way. Too many variables. I have AR's in 1/12, 1/9 and 1/7, they all have their uses for different applications.
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Agreed, this is another one of those arguments where the more you shoot the less interesting it becomes...I say either one is fine for 99.9% of us...the 1/9s are a bit more accurate(in my experience) with commercial loads. I currently have 1/9" 1/8" and 1/7" ...
 
sparrow said:
Agreed, this is another one of those arguments where the more you shoot the less interesting it becomes...I say either one is fine for 99.9% of us...the 1/9s are a bit more accurate(in my experience) with commercial loads. I currently have 1/9" 1/8" and 1/7" ...
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I agree with your agreement. My most accurate barrels are 1/9, with my 20" shooting from 52 to 75gn (Hornady) very nicely. I just picked up a box of 77gn SMKs which I'm going to try next in it and will report the results.

Going back to back, my 20" 1/7 won't shoot most cheaper 55gn loads as well as my 1/9 does. More fliers to be specific, otherwise pretty similar. For 80gn+ match ammo, the 1/7 is obviously a good choice, but I've never even held a 80+gn 224 bullet and I don't see me needing them anytime soon (longest range I can shoot at is 600m).

Looking at manufacturers offerings, how many offer their 'accurized' AR15 rifles with a 1/7 twist? Colt does a 1/9 on theirs, most others 1/8, I don't know of any major manufacturer who uses a 1/7 in an "accurized' model. The Swiss went with a 1/10 for their 63gn ammo, and I trust the Swiss to care about these things. YMMV, of course, but, the manufacturers seem to agree that 1/9 is the most accurate with most ammo. There is no difference in manufacturing costs between the two rates of twist.

If I was only shooting 55gn I'd probably go with a 1/12, but I do shoot a fair bit of 62gn ammo and the 1/9 handles both great.

"who would want 1:9 over 1:7? I dont get why RRA and other manufacturers make this twist when 1:7 seems to stabilize all the good rounds out there"
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-I think they would tell you that most ammo being shot isn't the 'good stuff'. Most of it is cheap 55gn FMJ and 62gn surplus, the ammo where I personally find more fliers with my 1/7, and I presume, so do the manufacturers. I can speak for Stag Arms take on this, because I asked the CEO exactly this question, and his response was "Because I don't want to have to spend my days on the phone explaining to shop owners why their customers rifles won't group well with the most common ammunition they sell." This is also when I was told that their 1/9 is closer to 1/8.5 and should stabilize most any mag loadable ammo.

The vast vast vast majority of 223 ammo commercially sold in the USA is <62gns, and the 1/9 is superior there, that's why almost everyone offers the bulk of their lineup in 1/9.

As Leg said, the US Military went with 1/7 due to the length of the tracer round, not due to better accuracy with 62gn M855 ball ammo. I know we have a few customers who put 20" 1/9 uppers on their C7 lowers for matches, as they find they shoot C77 ball more consistently.

There is no conspiracy here, and it's not a lack of knowledge on the manufacturers part.

But, back to Sparrows comment on twist, "the more you shoot the less interesting it becomes". I've heard this now from more than one active shooter actually, and the more I shoot the more I agree. Truth. :sniper:
 
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Forgot to say, I think that when it comes to accuracy, the quality of the manufacturing process is likely more important than the difference between a 7" or a 9" twist.

The better made barrel with either twist will shoot more accurately than the inferior barrel with either twist. I'm not talking type of steel, I'm talking concentricity of bore, quality of rifling, crown, etc, etc.

And Edit to Add: I forgot about my 10.3" 1/7, which if I recall correctly is more accurate at 100m than my 1/9 20" with just about any ammo. So who the F*** knows!? :)
 
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