IF op can legally use a .223 for deer... still hasn’t said what state.
My current state only allow hunting deer with a shotgun.
In that case, and since deer hunting was only a possibility, not a requirement, I'd recommend a fast-twist .223 all day. Love 6mms, but barrel life is a fraction of the .223s (factory 6s, anyway), and ammo and components pricier. Oodles of rifles to choose from too, including some that are scaled nicely to fit the little cartridge.
FWIW, if I were limited to one rifle, it would be an FN Mauser of some sort, probably a .270, no doubt about it. That's for me, not anyone else.
