I saw the video in rookie school, a man with a knife can get you from 15-20' away before you can draw and fire. I'm not giving any warning to a knife wielding attacker. He better drop it before I clear my holster, because I'm gonna shoot.
Springfield Armory XD-9 Service Model/Winchester Ranger SXT 127gr +P+ JHP
Beretta 21A .22LR/ CCI Quik-Shoks
Norinco SKS/ Wolf 7.62x39 FMJ