I have spent a long time debating the same question you're now asking. For SHTF you can't go wrong with a 9mm. Personally I'm going with 40s&w because I own a glock23 BUT you should honestly invest in a Glock 17... They withstand more torture tests than any other firearm...and they always shoot afterward...sounds like a gun you can depend on now doesn't it
this weapon will hold 17,19 and even 33 rounds!!! Don't settle for anything else, when SHTF you'll be wishing you had a glock trust me.