If I was forced to shoot an elk sized animal with my daughter's .243, there is no doubt in this world, I would take the 80 gr ttsx she currently shoots.
That bullet has a low S.D. For a big animal like an elk, I'd go heavier.
I know, monos perform better fast and going light helps with velocity. For elk, I'd go as heavy as my .243 twist would allow. I'd be concerned about penetration. Low S.D. bullets may lose their mojo before penetrating deep enough.
WT's and hogs, the 80 should do OK at .243 speeds. For me, that bullet sorta wimped out at .240 speeds on a WT doe. In that case, low S.D. and hypervelocity didn't mix very well. Seems to me terminal performance can be a balancing act.
