Ok I need this splaind to me.  

The older Ar's had a 1 in 7 twist barrel. The were using the 55 grain bullet.  

The newer barrels are 1 in 9 twist. And are using the "green" 62 grain round.  

WHY did they do this.  If I was to use the 62 grain in a 1/7 barrel that should give me a heaver round spinning faster with better long range placement with hopfully slightly better hitting power.

Just a thought.

If I am wrong I better stop sniffing my rifle bore cleaner (mil spec).  WHHHEeeeeeee.

Buzz.

Actually the older barrels were 1 in 12 and still is excellent for 55 grain bullets, but nothing heavier.  The 1 in 7,8,9, are good for 55 grain, but excellent for 62 grain and above weighted bullets.  My favorite bullet for my Colt 1 in 8 barrel is 69 grain Sierra Match King VLD.

So if you were to use the 62 grainer with a 1/12 twist you can "burn out" the barrel in these things. Right?

So what would be the best barrle twist for non-cqb.  

Can you even find barrels in 1/9 twist?

Most of your barrels produced now are 1 in 9,  kinda one twist for all, so to speak.  Do a search at RRA, Colt, Bushmaster, Armalite and you'll see.  Oh, and 55 grain is maximun for stabilization in a 1 in 12 twist.  Can you shoot a 62 grain bullet in a 1 in 12 barrel, heck yeah, accurate...not really, but I did stay in a Holiday Inn Express last night.

As usual, P806 is right on the money.  Most new barrels are 1:9 twist.  If you just want to shoot 55-grain and 62-grain ammo, the 1:9 is just fine.

P806...where did you find a Colt 1:8?

Quoted: P806...where did you find a Colt 1:8?

ooops, it's 1:7, just opened the safe and checked.  OK, I take back the hair comment, ole buddy ole pal.