AR-15 Barrel Length?? I?ve been lusting for an AR-15 for quite some time. I know exactly what I want in an AR with the exception of barrel length. The goal is an accurate/reliable 300 yard coyote/fox/bobcat killer in a compact package. Does anyone have any experience with an 18? barrel on an AR? I?d really like an 18? barrel but would go to 20? if necessary. I don?t want anything over 20?. I have other long guns for beyond 300 yards. .