TAC really does work better with heavier bullets in the .223. I shoot a lot of 69 grain SMK's in 16 and 20" barreled AR15 pattern rifles. In the 20" guns I'm in the 2840 FPS range (although I have not chrono'd this load recently or extensively.) A buddy of mine is using it in his "High Power" setup this year, he did a lot of chronographing with various powders and 77 and 80 something grain match bullets this winter. He said TAC was the winner each time by 50-100 FPS. I don't know what kind of speeds he obtained, but I believe him. Now if a ball powder can make it 88 rounds without powder fouling causing a drop off in 10 ring accuracy is another issue...
