After shooting mule deer, pronghorn, and elk with a few different calibers I would go with a bolt action rifle with a 3-9 X scope . The cartridge would be a Rem 7 MM Mag. A person who reloads ammo can get 100, 120,139, 154, 162, and 175 grain bullets. I may have missed a few bullet grains. -- My first rifle was a Winchester Mdl 70 270 Win purchased in 1952. Since back then , I have also used a 243 Win, 257 Roberts, 25-06 Rem, 264 Win Mag, 30-30, 308 Wim, 30-06 Springfeild, 308 Norma Mag, and 340 Weatherby Mag. My second choice would be a 300 Win Mag. Any one of the cartridges I have used will do with a bullet that matches the game and one stalks the game within range for the rifle.