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Posted: 10/8/2003 6:23:54 PM EDT
If I was looking for the best twist rate on a 14.5"inch M-4 barrel to destabilize a 55gr to 62gr bullet what would it be? The weapon would only be used for C/Q/C and SHTF (under 100 yard use)and accuracy is not a major concern.
Link Posted: 10/8/2003 6:41:11 PM EDT
[Last Edit: 10/8/2003 6:41:59 PM EDT by 5subslr5]
Originally Posted By Phila-PD: If I was looking for the best twist rate on a 14.5"inch M-4 barrel to destabilize a 55gr to 62gr bullet what would it be? The weapon would only be used for C/Q/C and SHTF (under 100 yard use)and accuracy is not a major concern.
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Phila-PD, I'm pretty sure you meant to state 'stabilize' and not "destabilize". A 1:9 twist will work and be very easy to find but a 1:12 would be best. With your qualifier ".....accuracy is not a major concern" I would get the 1:9. 5sub
Link Posted: 10/8/2003 7:40:15 PM EDT
[Last Edit: 10/8/2003 7:41:28 PM EDT by mach6]
Originally Posted By Phila-PD: If I was looking for the best twist rate on a 14.5"inch M-4 barrel to destabilize a 55gr to 62gr bullet what would it be? The weapon would only be used for C/Q/C and SHTF (under 100 yard use)and accuracy is not a major concern.
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-------------- To my mind, a 1:9 ROT is the way to go, given what you specified. In fact there is a certain variant of the M-16 (I say "M-16 variant" very loosely) to be procurred in limited numbers by an Army element that has that ROT specifically for that reason. That ROT offers an excellent compromise for long barrel life -- in auto fire, naturally and the ability to digest and stabilize rounds between 52 and 69 grains.
Link Posted: 10/8/2003 8:25:20 PM EDT
Go 1/7 or at least 1/9. 1/7 offers you wider selection of ammunition in terms of using very effective OTMs. (75/77gr) 1/7 will also shoot 55gr and 62gr just fine. (maybe a little bit less accurate than 1/9 but this isn't a competition rifle)
Link Posted: 10/8/2003 8:57:49 PM EDT
[Last Edit: 10/8/2003 9:00:31 PM EDT by Prosise]
www.ammo-oracle.com read this carefully... Prosise
Link Posted: 10/8/2003 9:20:42 PM EDT
1:9 twist
Link Posted: 10/8/2003 9:53:41 PM EDT
1:9 unless you want to use tracers (then use a 1:7). Tracers are a CQB no-no IMO.
Link Posted: 10/8/2003 10:09:16 PM EDT
I second the Ammo-oracle.com link. DEFINATLEY read that, it addresses this very issue.
Link Posted: 10/8/2003 10:20:47 PM EDT
I think this guy is thinkig twist affects bullet yaw/tumble and terminal effectiveness. It does not. 1/12 is perfect for 55 grain and it wont stabilize 62 grain. 1/9 is perfect for 62 grain. 1/7 would be ideal as it will stabilize everything from 77 to 55 grains.
Link Posted: 10/8/2003 10:22:55 PM EDT
Originally Posted By mach6:
Originally Posted By Phila-PD: If I was looking for the best twist rate on a 14.5"inch M-4 barrel to destabilize a 55gr to 62gr bullet what would it be? The weapon would only be used for C/Q/C and SHTF (under 100 yard use)and accuracy is not a major concern.
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-------------- To my mind, a 1:9 ROT is the way to go, given what you specified. In fact there is a certain variant of the M-16 (I say "M-16 variant" very loosely) to be procurred in limited numbers by an Army element that has that ROT specifically for that reason. That ROT offers an excellent compromise for long barrel life -- in auto fire, naturally and the ability to digest and stabilize rounds between 52 and 69 grains.
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I say your completely full of shit. Please prove me wrong. It would be cool if I am wrong here but I doubt it. I cant think of a single reason 1/9 would be used by the military. Not one.
Link Posted: 10/8/2003 10:23:45 PM EDT
Originally Posted By pulpsmack: 1:9 unless you want to use tracers (then use a 1:7). Tracers are a CQB no-no IMO.
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What if he wants to use 75 or 77 grain ammo?
Link Posted: 10/9/2003 6:00:27 PM EDT
Does twist rate affect bullet yaw/tumble and terminal effectiveness. This is the question I was requesting information on, Im sorry, I should have made that clearer.
Link Posted: 10/9/2003 6:21:17 PM EDT
[Last Edit: 10/9/2003 6:23:33 PM EDT by 5subslr5]
Originally Posted By Phila-PD: Does twist rate affect bullet yaw/tumble and terminal effectiveness. This is the question I was requesting information on, Im sorry, I should have made that clearer.
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PD, I 'think' what you're really after is "terminal effectiveness". If you're determined to use a 14.5" barrel, and that's what you're asking about, go to a 1:7 twist barrel and move up to 75-77grn bullets. The heavier bullets will give you the knock-down power and penetration that I believe you're after - within about 100 yards. The military had to make the move to heavier bullets based on their experience in the Afghan. Please remember that the AR-15 is an SCHV weapon. Without velocity (or heavy bullets) you've just got a .22. If I were going to spec a weapon for what I think you're after, I would use an 18" barrel with A 1:9 twist and 69grn bullets. But that's just my opinion. (I'm too tired to get in a long pissing contest tonight.) 5SUB
Link Posted: 10/9/2003 6:31:23 PM EDT
Originally Posted By Phila-PD: If I was looking for the best twist rate on a 14.5"inch M-4 barrel to destabilize a 55gr to 62gr bullet what would it be? The weapon would only be used for C/Q/C and SHTF (under 100 yard use)and accuracy is not a major concern.
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PD, I've again read both your posts and since you use words such as "destabilize, yaw and tumble" I'm wondering if you're remembering an old fable about the 5.56mm/.223 round tumbling and, therefore, making large holes in the victim ??? If so, with proper 'velocity' we now know the bullet fragments. Barrel length, far more than twist, determines velocity.
Link Posted: 10/9/2003 7:16:52 PM EDT
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