If considering a 6.5BR caliber AR that would push a 123gr bullet to around 2750-2800 from a 20" barrel, a 100gr TTSX to 2900-2950fps, which barrel length and profile would be the most chosen? I think most would use it for hunting or target shooting maybe a longer range comp gun. They only hold 10 rounds so it would not IMO be a good idea for making major in 3 gun. Since this is about accuracy with high BC bullets it seems most would want a mid to HBAR weight barrel 18-20" but that’s just my guess, what do you think?
You are mistaken about 6.5 magazines; they hold 25 rounds. I have a Sabre Defence SPR barrel that is 18 inches and fluted to reduce weight, though it’s expensive. Hope that helps.