Shot placement is everything. Hits not delivered directly to the ‘fatal t’ may be lethal but not immediately so. This was the case in the FBI Miami shootout, where IIRC all of the law enforcement casualties came after the perp had sustained a “non-survivable” wound.
Falconer showed a warrior heart, well trained and disciplined. I doubt many people could deliver the shots he did with greater precision. The fine marksmanship skills that one may display on the range that allow you to hit the head of a stationary paper target at 25 yards go right out the window in a real CQB.
Practice shooting on the move. Practice moving to and shooting from cover. Practice tactical reloading and jam clearing. Carry the largest caliber weapon that you can shoot rapidly and effectively. All else being equal, the bigger the permanent wound channel, the more rapidly incapacitation will set in. It isn’t instantaneous. Stay behind cover and keep your weapon trained until the target is good and ‘incapacitated’.
The only thing I would add to your comment, when it comes to knock down power, bigger is better, as long as the shooter can recover swiftly for follow up shots.