I have taken a back up gun several times on hunting trips. My reasoning was also to have a spare in case of Mechaniacl trouble with the main gun or scope. I never have had to use the spare gun as my rifle or optica have never failed me. It is a good plan though if you are traveling a goodly distance. As far as spreading out the calibers, If it is a backup gun I would want one that performs in a very simular way ballistically.