An extra mag is not necessary.
I carry a spare ALWAYS as I may indeed deplete the magazine in my single stack CCW pistols (Kahr PM9 and Seecamp .32). In addition I may experience a stoppage that leads me to performing the immediate actions to clear a doublefeed.
I believe an extra magazine IS necessary, even when I CCW a Glock 19. I’m going to do everything possible to ensure my success in winning a deadly confrontation - and it may require a spare magazine.
Yes, "all the pros" recommend it. SO it must be so. I did back it up. Recognizing a failure, diagnosing it, digging out the mag and changing it is all going to take 8 seconds. Minimum.
And your other choice is to have an empty gun and be powerless? That's fatalistic thinking, IMO.
Diagnostic techniques are slow because the shooter must transition through the OODA Loop in sequential order. The shooter first Observes the pistol didn’t fire when he pressed the trigger. Then he has to Orient to the situation – inspect the pistol to determine the type of failure and Decide what action to perform to clear the stoppage, and then Act to implement the decision.
(In addition you may mis-diagnose an in-line stovepipe, a doublefeed stoppage or a failure to feed because they may have the same appearance as a pistol that's been fired to slide lock, especially in low light. This corrupts the "Orientation" phase of the OODA Loop and leads to an incorrect Decision, which increases the time to adapt to the situation.)
I use a non-diagnostic technique which short circuits the OODA Loop to “Observe-Act”
When the pistol fails to fire then Tap, Roll & Rack is my immediate action. It takes about a second to perform.
If Tap, Roll and Rack fails to get the pistol running then I have a decision to make: react or reload? Depending on the situation it may be more important to react to the danger to keep from being shot, stabbed, bludgeoned, stomped, etc., before I have the opportunity to perform a Combat Reload.
Performing Tap, Roll and Rack doesn’t divert my attention from the external problem (the bad guy who’s trying to harm me) to deal with an internal problem (my gun stopped firing). Tap, Roll & Rack is performed automatically. If it doesn’t get the gun running then my mind is free to decide what to do next – react or reload. Reacting to danger may be more important than getting my gun running. (The first rule of a gunfight is - Don’t get shot. The second rule of a gunfight is - If you do get shot, drive-on and don’t give up.)
If Tap, Roll & Rack failed to get the gun running, then when time and conditions permit, I attempt to perform a Combat Reload (because I’m more likely to have emptied the magazine than to have encountered a doublefeed). If I can’t insert the fresh magazine into the pistol because the “depleted” magazine failed to jettison when I operated the magazine release then I immediately put the fresh magazine between the ring and pinky fingers of my firing hand, Roll, Rack & Lock the slide open, rip the “depleted” magazine from the pistol, Roll & Rack three times to clear the action, Retrieve the fresh magazine and finish the Combat Reload (Seat, Roll & rack). Progressing sequentially from Tap, Roll & Rack; attempting to perform a Combat Reload; and performing the actions to clear a doublefeed takes me about 8 seconds. It will take longer if I have to react to the danger. In addition I can perform it while on the move and in total darkness.
If the depleted magazine jettisoned when I worked the magazine release when I first attempted to perform a Combat Reload then I can have the gun back up and running in about 3-4 seconds if the situation allows me to immediately perform a Combat Reload when Tap, Roll & Rack failed to get the gun running.
I don’t care what caused the gun to stop firing. I just progress sequentially through a series of immediate actions until I get the gun running. If “A” doesn’t work then I perform “B”. If “B” doesn’t work then I perform “C”. There’s no diagnosing or thinking required. My mind is free to deal with the external tactical problem while I’m working the get the gun back up and running.
A = Tap, Roll & Rack
B = React/Reload
C = Clear the doublefeed and complete the Combat Reload
