One of the common complaints when it comes to shotguns and home defense is capacity. A shotgun might hold as few as 5 or 6 shells, while other long guns, like an AR-15, normally have at least 28 rounds on board. That is over 4 times the capacity of a shotgun. So surely, this argument isn’t wrong. Or is it?
The Fallacy
Often we look at capacity comparisons as a one-for-one deal. Usually, it is one deal. The shotgun, though, is different than most other guns. Usually, one press of the trigger equals one projectile downrange to hit the intended target (hopefully). One trigger press sends 8 or 9 projectiles downrange on a shotgun, though (assuming a 00 buck load). It is both the greatest strength of the shotgun and can sometimes also be one of its most significant weaknesses. That is a lot of lead on target all at once. It has a tendency to overwhelm the body and just shut it down. Many moons ago, a long-time SWAT operator that I know was talking about shotguns. He said the fastest he ever saw anyone die was a guy they had to shoot with a shotgun. Trigger press for trigger press, the shotgun is putting more lead in the target if the person behind the gun is doing their part.
The Serving Size
If we change the way we look at capacity and look past direct comparisons and think of it in serving size, we get a more accurate picture. A “serving” is defined as a payload sufficient to have the desired effect on the target—enough horsepower to stop the other person from continuing the fight whether they want to or not. With shotguns, that is typically one solid hit. We can see that in this video. (Editor Note: The video is age-restricted so I am unable to embed it within the post.)
With rifles, we typically are not taught to only fire single rounds. It is usually at least 2, and most of the time, somewhere around 3-5 rounds to give ourselves the best chance to incapacitate a threat as quickly as possible. Suppose each target requires 4 rounds (we will split the difference, plus easier math), then that 28 round magazine only has 7 servings. Now the capacity difference between AR-15 with a 28 round magazine and shotgun with 5 rounds in the magazine tube isn’t quite significant. In some cases where the shotgun has a magazine tube extension, even equal.
Those 4 rounds out of the AR-15 will probably take at least twice as long to deliver on target. With a 12ga shotgun, assuming proper load selection, each trigger press is a serving size. With a carbine, we are looking at 3-5 trigger presses. The amount of time it takes to press the trigger 3-5 times vs. 1 time is not insignificant.
Apples & Oranges
So when we think about capacity with long guns, it isn’t always an apples-to-apples comparison. Sometimes it is an apples to oranges comparison, and we have to do a little extra analysis to arrive at a correct comparison. Hat tip to Tom Givens for being the guy who I first heard make this type of comparison. He does the same thing with handguns, but that article is for a different day.
Don’t know where you buy your AR15 mags that they “normally” hold 28 rounds. Every one I own holds 30 and I’m pretty sure that’s the “normal” capacity. So, 30 in the mag and 1 in the chamber = 31 … not 28.
It is fairly common practice to download AR magazines by two. This makes it easier to insert a magazine on a closed bolt and/or cycle the bolt on a loaded magazine. Assuming the long gun is stored magazine loaded and chamber empty, as is also common practice, that makes it a 28 round gun. Either way though, it doesn’t change the calculus enough to really matter.