Just got my xmas present for the year. Armalite AR-10T chambered in 260 rem. This rifle was built for 1000 yrd competition. Pretty stoked as this is going to be a new challenge in loading a semi auto match rifle. I'm looking at 129 ablr. It has a shillen barrel with 1:8 twist. I have RL 19 and RL 17. As well as many slower powders but it seems the mid range burn rate is the place to be.