If you have firearms that work with detachable box magazines, you darn sure want more than one.
The magazine is one of the major causes of malfunctions. If you only have one and it goes belly up, your gun just became a single shot.
Going to a shooting match? You probably want to bring a minimum of two for a bullseye match, four or six for anything where the shooting is much faster than that.
Do you ever have to rent a range to shoot on? You’re paying for the time. I’d rather go there with a bunch of full magazines and spend that expensive time shooting instead of refilling cartridges.
Ever notice most uniformed police carry two extra magazines in addition to the one in their service pistol? And some carry more? When violent crime strikes and you are Society’s designated gunfighter, it is worse than unseemly to run out of ammunition.
Private citizen carrying a pistol? At least one spare magazine ain’t a bad idea. It’s not just for firepower. Remember, if the gun malfunctions due to a defective mag or a mis-shapen cartridge therein, ripping the compromised mag out and shoving a fresh one in is the quickest fix. Finally, you know how anti-gunners are always claiming the bad guy will just get your gun away from you and shoot you with it? A struggle for the gun can cause the mag release to be activated, and when you regain control of the pistol you don’t want to have to look in the snow, the mud or the darkness to get your pistol loaded again.
A side note on magazines: Having recently gotten great deals on 2 Beretta 9mm pistols (APX/92) I found it extremely difficult to load the last few rounds into the new magazines. I broke down and bought an Uplula magazine loader and now wish I’d gotten it years ago. Game changer for sure.
I used to carry an Officer’s-size Springfield Micro-Compact and found that the tiny little 3″ barrel and slide required Wilson Combat Officer’s 7-round magazines to work properly. It cycled so fast that you need REALLY strong mag springs to reliably feed. I ended up with 2 dozen of them.
When I switched over to a Sig C3 (Officer’s-size grip frame with Commander-length 4.25″ barrel and slide) I found that with the longer slide (and slower cycle time) it could use regular 8-round (McCormick PowerMags) but still carry with the 7-round mags. When I was testing it for carry reliability I fired 700 rounds of every kind of .45 ammo I had (3 different bullet types, a bunch of different manufacturers) and had exactly three (3) failures running through all 24 mags. All three of those were with a single magazine.
Sadly that magazine didn’t make it home. Somehow it got flattened under my boot heel at the range.
I go to the range every couple of months and shoot off my three magazines of carry ammo. Then I typically switch over to a .22 (Ruger 22/45) to save money. I always bring three magazines with me that are already loaded with good 230-grain HP’s; I cycle through all of the magazines doing this eventually. I’ve found that putting a number on the basepad with a silver-colored “Sharpie” permanent marker helps me keep track of them…it also helped me remember which one didn’t work well.
Mr. Ayoob, I also want to mention that I put at least a half-dozen loads of a couple of different brands of carry ammo through any NEW magazine that I get, just to make sure that the pistol/ammo/magazine combination works reliably.