Originally Posted By: ZeeOSix
Originally Posted By: hatt
Originally Posted By: Shannow
My CZ527 being made in the same factory as the mil stuff has the NATO chambering...well at least I can seat a 63 gr military projectile completely out of a properly trimmed case and still not touch the rifling (boat-tail is still in, but not gripped).
Can't shoot mil stuff with the 1:12, but it will still do MOA with 60gr VMax punted as fast as I can with AR2206 (close to 3031).
1:12 is perfect for M193.
M193 is 55 grains
From AR15.com:
About Barrel Twist
By Corey Sattler (
[email protected])
Here is the info I have collected for .223 twist ratios from various sources (including in-house testing & ammo manf. contacts).
1x7 - technically too tight of a twist for any .224 bullet widely available, including the 80 gr. Manufactured originally to stabilize SS109 and/or tracer ammo, but further military testing has shown other twists to be superior. Some of the very heavy custom stuff (87 gr?) may work well, but why????
1x8 - great twist for 69-80 gr bullets. Sierra once informed me that the perfect twist for their 80gr was 1x8.2xxxxx (blah blah blah big long engineers explanation followed).
1x9 - good all around twist ratio. Best suited for 52-69 gr, but either end of the envelope will be questionable.
1x10 - practically the same as 1x9, but favors the lighter side a little more.
1x12 - great for the 40-52 gr bullets. Most often found on bolt action rifles as their primary use is varminting. All right for the 55 gr, but not the best.
1x14 - if you want to under stabilize the .224 bullet, use this twist. Useless except for tumbling effect it causes upon bullet impact. IMHO, better to shoot straight with a good HP bullet as your chances to hit are better and damage will most likely be greater also.
And also:
Barrel Twist
The barrel’s twist rate refers to the distance a bullet travels in the barrel to complete a full revolution. For instance, a 1/9" twist means that the bullet will make a complete revolution for each 9 inches traveled in the barrel. Heavier bullets require a faster twist rate to stabilize them correctly, but too fast of a twist rate will potentially cause a bullet to spin apart. For this reason it is important to match a barrel to the bullets being fired. In selecting a single twist rate for the survival AR, either a 1/7" or a 1/9" will serve the purpose best. These barrels are designed for bullets from 55 to 62 grains, and these are the weights that will most likely be used in survival. The 1/9 is the better of the two, but the majority of Colts/military barrels are 1/7.
The right twist and barrel length is the name of the game. I have a few custom rifles ranging from 6.5x284, up to 30x338 Lapua. I had them built around the bullet I planned on using. There are a lot of people out there getting into reloading, learning about BC, heavier bullets etc. and wondering why bullets key-holing, etc. when they hit.