For self defense any DA like the M9, CZ75, Sig etc. should be carried with round chambered and hammer down and safety off. Like a revolver, pull, aim and squeeze the trigger and the gun shoots. Cocked and Locked, condition 1 is for SA guns only like 1911's and Browning HP's. Glocks, S&W MP autos, XD's and other similar actions carry round in the chamber.
Combat situations put the pistol away and get a rifle, shotgun or SMG.