I use the 80 grain TTSX in my .243.
Superformance powder doing 3,300 fps, 1 in 10 twist, 22" barrel.
Shot quite an number of fallow with them, including a handful of sizeable bucks during the rut with no problem. Culled a good few red hinds and followers as well, had good exits on every animal taken, from 30 to 200+ yards... nothing went further than usual either, most down within 10 strides or less.