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Posted: 1/12/2006 4:21:20 PM EDT
I have a 24" barrel that was given to me. I used it to my my AR. It has SS 5.56 on the barrel. My buddy told me it was a bushmaster. Can anyone tell me what they think the twist would be? I want to get the barrel cut down to 20". But I won't do it if the twist doesn't allow me to shoot more normal rounds.
Link Posted: 1/12/2006 4:50:06 PM EDT
It's most likely has a 1/9 twist. You can always put a brush on a cleaning rod, pull the brush through the barrel and watch how many times the rod spins. Take the number of spins and divide by 24 to get the twist rate. The odds are that even if the bbl isn't 1/9, it's possibly 1/8 or there is the remote chance it's 1/7 but that's highly unlikely.

BTW, what do you mean by "normal" rounds?
Link Posted: 1/12/2006 6:04:20 PM EDT

Originally Posted By eddienyr:
I have a 24" barrel that was given to me. I used it to my my AR. It has SS 5.56 on the barrel. My buddy told me it was a bushmaster. Can anyone tell me what they think the twist would be?



if it truly is a BM barrel it will be stamped what the twist is. look about 3-4" back from the muzzle.

ar-jedi

Link Posted: 1/12/2006 6:42:25 PM EDT
Bushmaster offers a 24" 5.56 caliber SS barrel... All of their advertised barrels come with 1:9" twist, except for the DCM barrels which are 1:8"...
Link Posted: 1/12/2006 9:02:51 PM EDT
Mat B

I read a post somewhere explaining bullet weights & barrel twists. By normal I mean what the recommended round weight vs the barrel twist.


So if in fact it is 1/9 it still would be a decent barrel at 20" ?
Link Posted: 1/13/2006 5:20:54 AM EDT

Originally Posted By eddienyr:
So if in fact it is 1/9 it still would be a decent barrel at 20" ?

Yes. A 1/9 can shoot 45gr to 69gr and some 1/9 bbls can shoot 75gr but you'll have to try yours to find out.
Link Posted: 1/13/2006 6:05:00 AM EDT
[Last Edit: 1/13/2006 6:12:39 AM EDT by theshootersden]

Originally Posted By eddienyr:
Mat B

I read a post somewhere explaining bullet weights & barrel twists. By normal I mean what the recommended round weight vs the barrel twist.


So if in fact it is 1/9 it still would be a decent barrel at 20" ?



ar15.com/forums/topic.html?b=3&f=12&t=264355

Bushmaster 16" barrels will stabilize 40-75 grain ammo... RRA's will too... And so will any other well made 1:9 twist 16" barrel...

www.bushmaster.com/le/tests/hornady_tactical_ammunition.htm

Link Posted: 1/21/2006 6:24:51 AM EDT
[Last Edit: 1/21/2006 6:25:17 AM EDT by SOSNBA]
1:9 is marginal for 75gr. 1:7 is a much better choice for 75gr +.
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