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Posted: 10/19/2004 5:59:18 AM EST
[Last Edit: 10/19/2004 7:05:33 AM EST by ASNixon]
I read the ammo-oracle and saw that 1:7 and 1:8 are mentioned as better twist rates for heavier ammo. My question is what are the performance differences between a 1:7 and 1:8 twist barrel with 75gr and 77gr rounds like the BH stuff? How much will it affect ballistics with these rounds?

Thanks.


Edited to add: I am asking this as it applies to 16" SS barrels.

Link Posted: 10/19/2004 12:47:21 PM EST
Both the 1 in 7 and the 1 in 8 will stabalize 75 gr and 77 gr bullets. NRA Highpower shooters have been using 1 in 8s to stabalize 80s for the 600 yard range for years now.

With a shorter 16" barrel, you would loose some velocity, so a slightly faster twist might be an advantage. However, I doubt you would notice the difference at 600 yards, and if you intend to keep your shooting within 300 yards I will pretty much guarentee it won't make a difference.

I got a 1 in 7 twist for my 16" M4gery. I wanted something faster than 1 in 9 twist, and I wanted chrome lining. I haven't seen any 1 in 8s with chrome lining.

My 20" DCM/NRA Highpower rifle has a stainless steel 1 in 8 twist barrel.
Link Posted: 10/19/2004 2:32:37 PM EST
Thanks DonS. I was referring to a 16" stainless barrel.



With a shorter 16" barrel, you would loose some velocity, so a slightly faster twist might be an advantage. However, I doubt you would notice the difference at 600 yards, and if you intend to keep your shooting within 300 yards I will pretty much guarentee it won't make a difference.



Sorry for the stupid question here since I am still learning this stuff, but you are saying the higher twist rate would possibly increase range? Or would change the trajectory? Or both? I am confused on this.

Link Posted: 10/19/2004 4:42:48 PM EST
also, if i might ask a question. What range of Gr bullets would you want to shoot through
1-8 Twist?
1-9 Twist?
Link Posted: 10/19/2004 6:05:46 PM EST
55-77
Link Posted: 10/19/2004 6:20:49 PM EST
Ok, we keep seeing this...

Basically THERE IS NO REASON TO HAVE A SLOWER TWIST THAN 1:7 UNLESS YOU SHOOT 50GR OR LIGHTER AMMO!
Link Posted: 10/20/2004 7:43:25 AM EST

Originally Posted By Dave_A:
Ok, we keep seeing this...

Basically THERE IS NO REASON TO HAVE A SLOWER TWIST THAN 1:7 UNLESS YOU SHOOT 50GR OR LIGHTER AMMO!


And there's no reason to have a faster twist rate than 1:8" if you are shooting anything magazine-length (ie, up to 77gr) and no tracers.

-z
Link Posted: 10/20/2004 7:57:40 AM EST
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