I would say anything that the police/nato carry. 9MM,40S&W,.223 and 5.56. Any AR-15 platform, and Glocks. Ammo will be readily available in a SHTF situation.
silverblazer50, I am not disagreeing or trying to say you're wrong, but I would like to understand your thought process better.
I would that think in most any SHTF situation the first thing to be cleaned out through purchase or theft would be guns & ammo... plus whomever was holding stores of ammo would be defending it to the death or joining up with like minded friends, family, neighbors, etc. to better protect against the loss of any life sustaining survival items.
Not to mention possible gov't intervention/ martial law at local, state, or federal level regardless of Constitution.
I would like to hear your thoughts cause you might be looking at things from an angle I haven't thought of.