The capacity of a firearm magazine should not make anyone high. But given the hyperbole over “high capacity” magazines, I fear some politicians are positively stoned.
Whenever there is a mad rush to legislation, accompanied by exaggerated sound bites, we at the Gun Facts project just have to take a closer look. Research is our drug of choice.
- Magazine capacity is only applicable to mass shootings
- Mass shootings are rare events
- Magazine capacity is not the underlying factor in high death rates
- The number of people killed at mass shootings is a tiny fraction of homicides
Exactly what is a “high” capacity magazine? It depends on who you ask. Ardent firearm enthusiasts consider a 30 round magazine commonplace and can cite meaningful usefulness for 100 round mags. Some gun control supporters believe anything over six is excessive.
As with “assault weapons”, “high” capacity is in the rheumy eyes of the politician. For sake of convenience, we will follow the two arbitrary legislative definitions of “high” capacity, namely 10+ or 15+ rounds. We do this so we can measure any alleged efficacy of such laws, but also because one of the common publicly available databases covering mass public shootings 1 lists in which events these types of magazines were used. This makes the math both reasonable and easy.
A note about other events
There is no reliable and comprehensive database concerning the magazine capacity of guns used in crimes outside of mass public shootings (MPSs). Even if there were, there are gun crimes where guns are not fired (e.g. ATM muggings). If anyone knows of a solid database that denotes magazine capacity for guns fired in the commission of a crime, and what the crime was, we would love to get our mitts on the numbers.
That being said, what we do know from sundry criminology reports is that for garden variety crime, magazine capacity isn’t an issue. The average number of rounds unleashed by criminals during a crime is between 2.04 for revolvers and 2.53 for automatics. 2 Hence, MPSs may be the only crime in which the capacity of the magazine matters.
Though for 27% of MPS, it may not matter at all. This is the percentage of cases in the Gun Facts Mass Public Shooting Database where the killer brought multiple guns. If 15+ round magazines are banned and the killer comes with three guns with 10 round magazines, he still has 30+ rounds to spend (assume one in the chamber) before the first reload.
This is an important point. In 2016, there were 11,788 arrests for murder and nonnegligent manslaughter 3. On average there are fewer than three MPSs in any given year in the United States, and some years there are none. From a purely death rate perspective, magazine capacity is simply a dumb policy point. To wit:
- Magazine capacity only matters in mass shootings, and even then not much (see more below)
- Mass shootings are rare
- The total fatalities from mass shootings, even including exceptional events (e.g. the Las Vegas country music massacre) are less than 0.2% of homicides
Given this alone, attempts to ban magazines of 10+ or 15+ rounds is an exercise in futility. Statistically speaking, such bans are meaningless.
On a purely raw number basis, larger capacity magazines look terrible in terms of MPS deaths. The misleading table at the right summarizes the number of MPSs and the number of people killed with various magazine capacities. But as the Gun Facts project likes to remind people, the Devil loathes details.
As other Gun Facts research (not yet published) has discovered, MPSs are increasing in frequency globally. The rate of increase of MPSs in the United States is actually slower than the rest of the world. But with the increase in the number of such events, we wondered if lunatics bent on mass murder were augmenting their armament. The event in Las Vegas was a vivid example of extreme lunacy and firepower (the shooter possessed 12 100-round magazines).
What we discovered though is that 15+ round magazines in MPSs have been the norm since at least the late 20th century. Any increase in their rate of use appears to be strictly a byproduct of the slow rate of increase in MPSs in general.
But does this mean more people are dying due to 15+ round magazines. The answer is “yes, but …”
Excuse the Skew
Since the number of incidents of MPSs using “high” capacity magazines is relatively static over time, we had to discover if they are inherently more lethal. As the argument for banning these magazines goes, “the less often you have to reload, the more people you can kill”. But as the Gun Facts project noted with our groundbreaking perspective on “cattle pen shootings”, the magazine capacity is secondary to the venue. Stated differently, fire from a 15+ round magazine into an empty room and the only thing you will kill is the furniture and your ammo budget.
When we mapped MPS incidents and fatalities, we saw a distinct pattern. For <10 round and 10-14 round magazines, the average number of people killed was 8.0 and 7.1 respectively (yes, fewer people are killed using the larger 10-14 round magazines).
The first interesting comparison point is that even including exceptional events (e.g. Las Vegas), the body count from shooters using 15+ round magazines was 11.9. Granted, this is 50% higher than the average for <10 round magazines, but numerically not a huge bump and is less than the magazine’s capacity. And given the relative infrequency of MPSs, the death rate is still a fraction of a fraction of a fraction of all gun homicides.
The next interesting bit was how well the number of incidents involving 15+ round magazines fit with MPSs employing smaller capacities. In other words, in most cases, the shooter stopped murdering people long before he ran out of ammo in his first magazine. This leads rational people (a.k.a. ‘not your congressman’) to conclude that deaths from MPSs are more a factor of location and people density than the weapon type of the magazine capacity, which is where the Gun Facts cattle pen scenario research is leading.
The third observation is that only eleven MPSs since 1998 in which 15+ round magazines were used – those with twelve or more people killed – accounted for just under 70% of the deaths in events using said magazines. If we look at just the events above where the next category of magazine shows on the chart – events with 26+ people killed – they account for half of all deaths. The point of these observations is that a small number of extreme events skews the death rate from 15+ round magazines. Without these over-the-top homicidal rages, you might not see a dime’s worth of difference between smaller capacity magazines and larger ones in terms of the number of people killed.
But let us not speculate. Let’s look at these exceptional events and see what commonalities we can glean from them:
|Killed||Cattle Pen||Mental Health Indicators||Gun Free Zone||Notes|
|58||Yes||Yes||Yes||Multiple 100 round magazines|
|49||Yes||Yes||Yes||“Jungle” taped magazines|
|32||Yes||Yes||Yes||15 round stock handgun magazines|
Here is the point of this exploration. As the charts above show, magazine capacity is not a reliable variable in term of the number of people killed in MPSs. That 20 MPSs where 15+ round magazines were used resulted in fewer than 10 people being killed – within two standard deviations of the mean for lower capacity magazines – means other variables are likely more important.
From the exceptional events – ones where many people died – all but one of the shooters had prior mental health issues, and all but one of the events occurred in a gun free zone.
BUT, ALL OF THESE EVENTS WERE CATTLE PEN SCENARIOS.
What to do, or not to do
Will bans on “high” capacity magazines make any difference at all? Not really.
Now, will a politician listen to numbers? I fear the current crop of legislators suffers from either mass delusions or mass innumeracy.
Update #1: How Many Lives Savable?
It occurred to us that it would be interesting to know how many MPS lives could be saved even if all 15+ round magazines were confiscated.
Excluding the Las Vegas Country Music massacre, in which 100 round magazines were used and thus is a very unusual case, we can derive this number. First we exclude incidents where the death rate was within the two standard deviation range of smaller capacity magazines. The logic here is that the shooter stopped long before they reached the end of even a first magazine of ammo, and thus not having a larger capacity magazine made no difference.
A maximum of 211 lives were at play. But as we see, the average body count using magazines <15 rounds was eight. We have to assume the shooter would have still gone on a rampage and used smaller capacity magazines.
When you do the subtractions, 123 lives over 20 years were in play, or about 12 lives per year. And even this is purely theoretical and optimistic.
Update #2: The Planning and Cattle Pen effect
A reader asked a great question, namely “If we remove the well planned events, how does magazine capacity figure into MPSs?”
The answer is quite profound. Below is a table where we we removed those events that (a) the Gun Facts MPS database classified as a “cattle pen scenario” and that (b) the Violence Project MPS database said were well-planned (we’ll note that both “cattle pen” and “well-planned” had 32 instances each, though it was not a 100% match between those factors).
As you can see there is no material difference in the number of people killed in MPSs based on magazine capacity. Aside from an inexplicable dip in the number wounded for mid-range magazine capacites, there is no material difference in the number of people wounded either.
|>= 15 rounds||6.8||5.2|