TTSX or TAC-TX? TAC-TX is the .300 BLK barrier-blind round specifically designed for that gun.Yeah I saw an elk this year killed with a 120 gr Barnes TTSX out of a .300 blackout. Went through and lodged under the skin of the opposite shoulder at 100 yds. Bull ran 60 yds and died. Certainly not a caliber that I would ever choose, but the performance of the mono bullet was quite impressive.