Small sample size for polar bears in this study but it has been found to be effective. https://www.bearwise.org/wp-content/uploads/2017/07/efficacy-of-bear-spr

Small sample size for polar bears in this study but it has been found to be effective. https://www.bearwise.org/wp-content/uploads/2017/07/efficacy-of-bear-spray-smith-et-al.-2010.pdf https://www.bearwise.org/wp-content/uploads/2017/07/efficacy... With a guns you might need one or more well placed shots, and if you're not trained and proficient, that will be almost impossible if you find yourself in a situation where a bear is charging at you. Pepper spray can be a lot easier to spray in a bear's face in such a situation. Might be best to have both spray and a gun handy, though.