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stumbled across this in the reviews section of ARFCOM
By Corey Sattler (Webmanager@olyarms.com)
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 understabilize 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.
About the author: Mr. Sattler is the Law Enforcement Sales Manager and Archival Records Manager at Olympic Arms, Inc. in Olympia, WA and has been with the company since 1993. He is also a Reserve Deputy in a small Southwest Washington county Sheriff's Office.
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Twist rate doesent care how heavy the bullet is, just how long it is.
The longest bullet you will find is a 90gn. Not seen much at all outside of high power shooters. Made by Sierra, Berger and JLK. Needs a 6.5-7 twist. Needs to be loaded long eliminating mag use. The jury is still out on if a 223 can push them fast enough to be better downrange than the old standby, the 80 Matchking.
The next heaviest/longest is the 80. Same thing. Not seen outside the high power shooters and needs to be loaded long eliminating mag use. Again made by Sierra, Berger, JLK and sometimes Nosler. Needs a 7.7-8 twist.
After those, the 69-77 are common. They need an 8 twist.
A steel core 62 is as long or a touch longer than a lead core 69. So the military just overstabilizes them. The 77gn match ammo does just fine out of the 7 twist M-4s.
If you are trying to shoot benchrest with an AR, get a 12-14 twist and dont ever plan on shooting anything longer/heavier than a 52 gn bullet.
Me, get a 7 or 8 twist and dont worry about it. It leaves you with options. Anything else ties your hands somewhere.
Corey (above) isn’t with Oly anymore, and I am one of the blah blah blah engineers of which he speaks.
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SO, again, still trying to understand this... is that information not any good?
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Coreys info is fine. I just wanted to make sure you understand required twist is a function of length, not weight.
My money would buy a Rock River, Armalite/Eagle or JP upper.
