As long as you do not break the 180 or sweep yourself or anyone else, I don't really care what you use aas long as it is at least 9x19. Will only need to have the pistol for the three stages it is used on. If you don't have a holster, that is okay too.
If folks don't have a pistol, bring $10 for a box of factory ammo and shoot one of the loaner PCCs.