AR15 Rifle length gas system

You probably won't get a better barrel than this for the price.

http://ar15performance.com/inc/sdetail/11562/18272

^^^

I own the unfluted version of this barrel and it is absolutely awesome. Maybe because my imagination is limited, but I can't imagine a better barrel.

If you're looking for a factory built rifle, that certainly limits your options. If you're building yourself, there are countless directions you could choose. So which are you planning?

Check out BCM.

Check out modelonesales.com

I wouldn't go shorter than 18 inches with a rifle system. The distance from the gas port to the end of the barrel determines dwell time you want enough to assure pressure to work the action.

I went with the 18" 1:8 SSS410 from bcm. They make several different flavors of uppers and bare barrels in fluted and unfluted.

Well narrow down what you want to do with the rifle.

Do you need to shoot long, high-BC bullets and need maximum accuracy, do you want chrome lining, does weight factor in...

Generally, if DD is on your list, you won't go wrong. But if you know exactly what you want (twist, barrel steel, profile, lining, etc), then it helps narrow everything down.