There are rules to a gun fight - 5 of them in fact:
1) Gun beats no gun
If you dont carry for reason X - you have no gun
If you can’t clear a jam - you have no gun
If you run out of ammo - you have no gun
2) Fast beats slow
He who gets his gun into the fight first, usually forces the other guy to take cover.
3) A hit beats a miss
A .22 that hits does a whole lot more damage than the .44 mag that misses
{subject to the above rules}
4) big holes beat little holes
Carry the biggest hole maker that you can that meets the above rules
5) Two holes beat one hole
If it is worth shooting once, shoot it again. Remember rule #1 with regards to ammo
#6: Bring friends with guns. :-)