Yeah, after digging a bit, I stand by the 6.5-300 Wby and the 30-378 Wby for flattest-shooting to 500 in factory cartridges. I don't know why one would want either for Texas deer, but it's not my money.
A super-fast 22 cal twisted at 7 to 8 and shooting 68-75gr would not be amiss for said use either. A 22-250 Ackley or 22-308 (Cheetah?) or Swift would be pretty flat, with low recoil.
A wildcat 6 on a magnum case would shoot damn flat, and spun for 105's, it would be quite effective. A twist to stabilize the 115's would give you a LR sweetie.
