Pick a rifle that suits you, then worry about the cartridge. Never been to Texas (yet), but aside from nilgai, anything from .243 up ought to work. I picked a Fieldcraft 6 Creedmoor for my old man rifle, but it could easily have been a .243, 6.5, .270, or 7-08. The thirty cal rounds are on the edge of comfort and shootability in such a light rifle, I believe, and not really needed here.
