What does everyone recommend for competition ar barrel length? I know 18" was the go to length but latetly I see more and more people using shorter barrels. Im heavily considering buying an Armalite 3gun model and can't decide between the 13.5 barrel with pinned comp or the 18" barrel. Both have adjustable gas blocks and tunable comps. The 18" has a rifle gas system and the 13.5 has a carbine gas system. I've heard great things about both, and from what I read both can be tuned to shoot very flat. I don't plan to compete a lot at this time, but would like a good ar if I decide to in the future. Reliability is a must. I currently have a 16" mid length, I could easily use for 3 gun too. It doesn't have a lot of lightened parts, but it's a soft shooter that's reliable and accurate. Thanks in advance for all your suggestio