As p loader suggests, the 6920 has 1:7 rifling.
When I was shopping for an AR, I had to familiarize myself with the various features, and which the cognoscenti considered good or not-so-good. The Colt rifles fared very well in that comparison.
I finally purchased a Colt, my single regret being that I bought it at close to peak price a few years back. The price was a steal at the time (from our very own WildAlaska), but since then some of the madness has abated, and prices have receded accordingly.
As an additional resource, you may want to go to ar15.com and click on the button for "AR15" to reach their forums. They have some very helpful information.
"...A humble and contrite heart, O God, thou wilt not despise." Ps. li
"When law and morality contradict each other, the citizen has the cruel alternative of either losing his moral sense or losing his respect for the law." —Frederic Bastiat