Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
User Panel

Page AR-15 » AR Discussions
AR Sponsor: bravocompany
Site Notices
Posted: 10/24/2003 6:58:43 PM EDT
I thought there was a post describing the different twist ratios and which is the optimum rate.

I primarily will shoot 100 yards (maybe 200 & 300), but would like to extend out further at one point and would like to know the recommended twist.
Link Posted: 10/24/2003 7:19:04 PM EDT
[#1]
Quoted:
I thought there was a post describing the different twist ratios and which is the optimum rate.

I primarily will shoot 100 yards (maybe 200 & 300), but would like to extend out further at one point and would like to know the recommended twist.
View Quote


JT, the twist rate is matched to bullet weight.  (Some will say bullet length but that's not pertinent to most civilian shooting.)  For example, a 1:9 twist barrel should be most accurate (optimum) with a 69grn bullet, a 1:12 with a 55grn bullet, etc.  

Other factors, such as barrel length, are more likely to affect distance.

5sub
Link Posted: 10/24/2003 7:23:32 PM EDT
[#2]
It appears many of the Match and Varmint rifles have a 1:8 twist. What bullet weight would be optimum for this?
Link Posted: 10/24/2003 7:35:55 PM EDT
[#3]
Quoted:
It appears many of the Match and Varmint rifles have a 1:8 twist. What bullet weight would be optimum for this?
View Quote


75grn
Link Posted: 10/24/2003 9:31:38 PM EDT
[#4]
the thing about twist rates as explained to me by DevL is that if you have a twist rate that is too slow, you will have really bad accuracy.  you will have the greatest accuracy if your twist rate is just barely fast enough to keep your bullet stabilized.  however, it is best not to be TOO close, because changes in temperature etc could cause you to cross that line.  by using bullets of lower grain, you will sacrifice a very small amount of accuracy.  a 1/8 twist is relatively fast and therefore will allow you to shoot a wide variety...so you can still shoot standard 55gr with accuracy, but you can also use the heavier 75gr if you want for some specific purposes, like slightly longer range shooting or something.
Link Posted: 10/24/2003 9:37:46 PM EDT
[#5]
...Or causing massive tissue damage in people sized creatures.  The 75 OTM is great at that too.

Technically the bullet length is matched to the twist not weight, but length often goes hand in hand with weight.
Link Posted: 10/24/2003 9:39:30 PM EDT
[#6]
heh good u didnt correct me on anything :)
Link Posted: 10/25/2003 6:38:00 AM EDT
[#7]
Quoted:


........ a 1/8 twist is relatively fast and therefore will allow you to shoot a wide variety...so you can still shoot standard 55gr with accuracy, but you can also use the heavier 75gr if you want for some specific purposes, like slightly longer range shooting or something.
View Quote


Actually the bullet weight range for a 1:8 twist barrel is 60-80grns.  (Agree on the heavier bullets for longer ranges.)
Link Posted: 10/27/2003 3:11:44 PM EDT
[#8]
Barrel twist rate and bullet weight are NOT matched for each other. The military uses a 1\7 because of the length of the tracer round. Most target shooters use a 1\8, but some are using a 1\6.5. Most commercial barrels are 1\9. For the most up to date information on this, check:

www.ammo-oracle.com
Link Posted: 10/27/2003 4:27:01 PM EDT
[#9]
Page AR-15 » AR Discussions
AR Sponsor: bravocompany
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.
Top Top