First rule of a gun fight: Bring a gun.
After that there are a myriad of variables that will affect the outcome. But it does (how do I say this nicely) make some of the overly zealous promoters of high capacity, big bore, expensive weeks of training, seem as though they reside in the village of tin foil hats.
I've often wondered why (other than personal enjoyment) some folk would pay many hundreds or thousands of dollars to train to be some kind of civilian black-ops type.
Don't misunderstand, some training (even if from a competent friend) and range practice is very important. If for no other reason to become familiar with the rules of gun safety, how to properly operate your weapon, and how to hit a target with some reasonable accuracy.