This term was brought into circulation by Massad Ayoob many years ago after learning that officers of the NYPD Stakeout Unit of the time, who were armed primarily with double-action revolvers, often moved to a second (or third) wheelgun when the ammunition was exhausted in their primary firearm.
Some self-defense enthusiasts have opined in the blogosphere that modern semi-automatic pistols, with magazine capacities of 15 rounds or more, have done away with the need to carry spare magazines filled with extra ammunition, let alone packing or staging a back-up gun of one type or another.
I, on the other hand, still side with “Uncle Mas” who also taught that if someone needs one gun, they probably need two guns. Here are just a few of the arguments in favor of back-up guns for home defense and concealed carry:
1. The first gun goes click instead of bang.
Despite our best efforts to purchase firearms from reputable manufacturers, load them with quality ammunition, and keep them in proper working order, firearms can still fail to operate properly at the most inconvenient times.
Some ammunition malfunctions, like a faulty pistol primer, can be dealt with quickly. Semi-automatic pistols can be cleared of a dud round using a tap-and-rack drill while double-action revolvers allow the user to cycle past a dead cartridge by simply pulling the trigger.
When an ammunition malfunction damages the gun (hot load) or leaves a bullet lodged in the barrel (squib load), there's no way to solve the problem on the spot. It's not uncommon for guns to be damaged in the course of a gun fight. Component failures, such as broken firing pins or damaged magazines, are not always easy to spot or prevent.
Not too long ago, I was testing a factory fresh semi-auto pistol which had, unbeknownst to me, a faulty takedown pin. The pin dropped out of the frame and then quietly rolled away while the pistol was resting on the shooting bench.
When the slide was pulled back and released to chamber a fresh round, the entire slide assembly (including the first cartridge from the magazine) launched off of the frame to land a few feet away. This was the first time (and hopefully the last) I've ever seen a pistol do this. But when something goes this wrong with a gun, moving over to a second gun is the only option to keep you in the fight.
2. A primary defensive gun is not accessible.
This is especially true in concealed-carry situations. By the time a defensive situation calls for a handgun to be drawn, the dominant shooting hand might be injured or occupied holding an attacker at bay. It's also possible for a primary gun to be dropped, knocked away, or you may be in a wrestling match with an assailant to maintain control of your gun.
Having a second gun somewhere else on your body provides a practical solution to these issues. Some self defenders carry a matched pair of handguns in the same caliber on both hips. Others carry a medium- or big-bore primary gun strong side with a small bore back-up tucked away in a pocket.
For someone who spends their days driving, a second gun in an ankle holster can be quickly accessed while a hip-holstered gun is blocked by the seatbelt. Regardless of the combination or placement of primary and back-up guns you choose, remember to carry extra ammo for both.
3. Additional guns can be used to arm other responsible adults.
I can't help but roll my eyes when watching some silly movie in which a man pulls out a handgun as he goes to investigate a noise in the night leaving his poor, helpless wife all alone with nothing but a good set of vocal chords to defend herself. Those Hollywood writers obviously haven't met the women I know.
I'll jump up and cheer right there in the movie theater when I see the scene where a bad guy rounds the corner to find himself facing a determined woman hunkered down on the far side of the bed with a tactical rifle leveled at the doorway barking out the command to "Show me your hands!"
If it's worth the time and money to stage one firearm for home defense, then make the effort to stage two. If the situation demands that you and your significant other split up, then both of you have the tools you need to protect yourselves.
If you do not agree on platform type, then by all means go ahead and get the guns you each like best. But make sure you both have a clear understanding of how to run the other's set up, just in case you need to. And again, make sure to have additional ammunition to keep both guns running.