well if i could only have one gun it would be a 700 remington problem is what cal i have a sweet made back in 1962 700bdl 308 that is my go to gun for deer and alike but i picked up a 700 bdl in 7mm mag and like it also for different reasons and hunting situations and if i had to choose only one gun for all my rifle hunting needs i may just go order a 700 bdl in 7mm STW assuming i can still handload not many loads avil for 7mmstw over counter but very useable cartridge from a 100 yds to 400 yds on most if not all north american game ok that being said now if this is an end of the world question i would grab my bushmaster m4gery and 30 mags and hide the rest of my guns !!