I’ve killed a few elk with a few different rifles/cartridges, .270, 7x57, 7mm Mag, 30-06, 338-06 and .338 Win Mag. I’m no doubt “old school” but a Winchester M-70 Featherweight in 30-06 would be tough to beat. My favorite bullet is the discontinued Hornady 190 gr. BTSP, however about any 165-180 gr. bullet will do. Plenty of ammunition anywhere you go and plenty of rifle if you’re in bear country.