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Posted: 1/9/2005 8:37:34 PM EDT
Exactly what the title states, What is 1:9 twist?

I was just a little fuzzy on what that means exactly.

Could someone enlighten me please?

Thanks.
Link Posted: 1/9/2005 8:39:35 PM EDT
[Last Edit: 1/9/2005 8:47:44 PM EDT by JohnTheTexican]
It means the rifling is cut so it takes 9 inches for the bullet to make one complete revolution.  The bullet will come out of a 1 in 9 twist barrel faster than a 1 in 12, and slowwer than a 1 in 7.  The heavier the bullet, the slower it moves, so heavier bullets need a faster twist rate.  But if you use lighter bullets, a too fast twist rate can also degrade accuracy and cause the bullets to disintegrate.  1 in 9 is fine unless you're going to be shooting unusually heavy bullets.  
Link Posted: 1/9/2005 8:45:20 PM EDT
Ah, why thank you.  I was kinda thinking that, but wasnt quite sure.  I couldnt find anything on this on the internet, so I thought I would try here.  Thanks again.
Link Posted: 1/9/2005 8:45:55 PM EDT
faster than a 1:12, slower than a 1:7. Glad I could help.
Link Posted: 1/9/2005 8:54:30 PM EDT
[Last Edit: 1/9/2005 8:55:01 PM EDT by HoustonHusker]
John,

Is there any problems using 55 to 77 grain bullets in a 16" barrel with a 1:9 twist?  Will the heavier-grained bullets be less stable out of the shorter barrel?

Thanks,

HH
Link Posted: 1/9/2005 8:57:11 PM EDT
1:9 will shoot just about anything.
Link Posted: 1/9/2005 9:02:28 PM EDT
Thanks, LW!

HH
Link Posted: 1/9/2005 9:02:57 PM EDT
[Last Edit: 1/9/2005 9:03:41 PM EDT by JohnTheTexican]

Originally Posted By HoustonHusker:
John,

Is there any problems using 55 to 77 grain bullets in a 16" barrel with a 1:9 twist?  Will the heavier-grained bullets be less stable out of the shorter barrel?

Thanks,

HH



Sorry, my knowledge is a bit more general than that.  I know you won't have any trouble with 55 or 62 grain bullets with a 16 inch 1-in-9 twist barrel, and I think you should be okay with the 77 grain bullets, but I'd ask someone with greater expertise.
Link Posted: 1/9/2005 9:07:36 PM EDT
Thanks, John...appreciate your help!

HH
Link Posted: 1/9/2005 9:15:58 PM EDT
[Last Edit: 1/9/2005 9:16:21 PM EDT by niceguymr]

Originally Posted By HoustonHusker:
John,

Is there any problems using 55 to 77 grain bullets in a 16" barrel with a 1:9 twist?  Will the heavier-grained bullets be less stable out of the shorter barrel?

Thanks,

HH



I'm a newbie so I don't know shiat... just to get that out of the way.

My understanding is that for anyting OVER 55gr, a 1 in 7 twist is better (meaning more accurate and stable in flight).  In fact a 1/7 twist is better for grains up to 77, according to the US Special Forces in Iraq.  1/9 is best for 55gr and under.
Link Posted: 1/9/2005 9:34:58 PM EDT
[Last Edit: 1/9/2005 9:37:30 PM EDT by I_H_R]

Originally Posted By HoustonHusker:
John,

Is there any problems using 55 to 77 grain bullets in a 16" barrel with a 1:9 twist?  Will the heavier-grained bullets be less stable out of the shorter barrel?

Thanks,

HH



If you are mainly shooting 69-77 grainers I would highly recommend a 1 in 7 but if you stay with the 55-69 grainers keep the 1 in 9.  That's my .02 anyway.

ETA:  The barrel length won't effect stability as much as twist rate with heavier bullets.  Lots of 14.5" M4's shooting the heavier bullets.
Link Posted: 1/9/2005 9:59:53 PM EDT
Thanks, niceguy and I_H_R,

I'm sure now I'll stick to the smaller stuff.  I appreciate you guys sharing your knowledge!

HH
Link Posted: 1/10/2005 6:30:54 AM EDT
Wayne1411 and HoustonHusker, if you haven't read the Ammo Oracle, you should.  It contains a lot of useful information regarding .223/5.56 ammunition, including several sections on twist rates and their effects.
Link Posted: 1/10/2005 5:43:03 PM EDT
The 62 grain SS109 bullet was origianl meant to be used in a 1/9 twist barrel.  Bullets longer than this have poor accuracy in many 1/9 twist barrels... especially in cold weather and short barrels.
Link Posted: 1/10/2005 6:10:14 PM EDT
why thank you sir.
Link Posted: 1/10/2005 6:29:24 PM EDT
Thanks, 77 and DevL!

HH
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