Re: 223 vs 308 to 600 yards..
Would you like a straight answer now?
in your scenario, give me an AR in .223 any day. Here's why:
1. Unless your Bill Gates, etc. you only have a limited budget to stock up on ammo. Compare prices on 100 each bullets; 75 or 77 grain bullets in .224's Verses 168 or 175 .308's. It's a no brainer. +1 for .223
2. According to my loads, my ballistic programs etc. .223 long range loads drop & drift the same as, or actually a little less than .308 long range loads. [EDIT: that is actually when running 80g VLD bullets, which will not mag feed]
<span style="text-decoration: line-through">+2 for the .223</span>
3. recoil: generally speaking, the lesser recoil, the more fluid the follow up shot or the engaging of the next target.
+3 for .223
4. as mentioned previously, you can carry a whole lot more .223 ammo over .308, ounce for ounce.
+4 for the .223
5. rate of fire coupled with economy:
A nice AR will shoot sub .5 moa. A really nice AR will shoot .3 moa. Sure the same can be said for .308 repeaters, but .308 repeaters are ridiculously more expensive.
+5 for the .223
As far as I'm concerned, the only thing the .308 has over the .223 is down range energy. In terms of on target energy, the little .223 runs out of gas before the heavier .308. But, in your 600 or less yard scenario, the .223 still has sufficient energy to get the job done.
somewhere (approximatly) around the 750 - 800 yard mark and beyond, a guy would be better off with the .308...
{according to current real world operators, as spoke of in the book "TriggerMen" -A lot of guys are carrying AR's for engagments inside 800 yds. now that they have the Black Hills 77grn loads and leaving their m24's behind.}
Understand my views/statments are with the (.223)Hornady 75bthp, or Sierra & Berger 77grn. bullets. Lesser/lighter .224's don't cut it.
FWIW.
T