Gun Control And Mass Shootings: Would Lives Be Saved?

An analysis of every US mass shooting over the past 30 years shows that two small policy changes, restricting high-capacity magazines and introducing stringent background checks, might have saved over 500 injuries and deaths, reducing total casualties in mass shootings by 50%.

Various proposals have been set forth since 2012’s numerous mass shootings, ranging from much stricter gun regulations to arming more individuals in public spaces. Starting from Mother Jones’ list of US mass shootings over the past 30 years, I analyzed the potential impact of two proposals in particular: would a ban on high-capacity gun magazines have reduced casualties, and would stringent background checks of gun purchasers have reduced the number of shootings? I researched the incidents surrounding each shooting to determine whether each proposal would have had any impact. The data are summarized in the table below, with the full research spreadsheet available here.

Shooting Deaths Injuries Lives Saved Injuries Prevented Weapon Legally Acquired? Notes
Totals: 459 481 250 324 Legal in 58 of 63 cases 54% of deaths and 67% of injuries might have been prevented with the policies analyzed.
Newtown, CT Sandy Hook Elementary 27 2 17 0 Yes – legal weapons in same household The shooter’s rampage was stopped by a quick police response. If the shooter had to reload 3 times as often, he would hit many less victims, as he fired on each victim multiple times.
Minneapolis, MN Sign Company 6 2 1 0 Yes The shooter reloaded at least once during the shooting, and initially struggled with victims.
Oak Creek, WI Sikh Temple 6 4 3 2 Yes In a public setting with many adults, it’s possible shooter would have been stopped while attempting to reload, or would have retreated outside more quickly if he had less capacity.
Aurora, CO Theater 12 59 12 59 Yes A lucky form of weapon capacity control prevented a larger disaster, as the shooter’s weapon jammed and he was only able to fire roughly 1/3 of the 100 round magazine. A properly integrated background check system might have stopped the incident entirely.
Seattle, WA Cafe 5 1 0 0 Yes It’s not clear that the gunman ever needed to reload, and though he had a history of mental health problems, he was never treated and never convicted of a felony.
Oakland, CA – Oikos University 7 3 7 3 Yes HCM limit would have no impact here, but the shooter was expelled from school for behavioral issues, which might have been caught if this data were submitted to a comprehensive background check system.
Atlanta, GA – Health Spa 4 0 4 0 Yes HCM limit and background check would have no impact here
Seal Beach, CA – Salon 8 1 3 0 Yes The shooter reloaded during the shooting per police reports, so lowering weapon capacity would likely have lowered casualties.
Carson City, NV – IHOP 4 7 2 3 Yes The shooter fired over 30 rounds per eyewitness accounts – lower capacity would have constrained him.
Tucson, AZ – Giffords shooting 6 13 4 9 Yes Shooter was tackled and stopped while he tried to reload – direct evidence that lower capacity would have decreased the toll.
Manchester, CT – Beer Company 8 2 4 1 Yes Shooter used two weapons and fired multiple rounds at many victims – had he been limited, he would have run out of ammunition earlier
Lakewood, WA – police officer shooting 4 0 0 0 No Capacity limits might not have helped, as the shooter fired on four victims seated at one table, and hit all of them with his initial salvo.
Ford Hood, TX – army base 13 29 9 19 Yes Shooter reloaded many times, and 30 round magazines enabled him to fire roughly 170 rounds before being shot himself by military police. Multiple soldiers attempted to charge the shooter – if he had only a 10 round magazine, it’s entirely possible that he would have been tackled and stopped upon initial reload.
Binghamton, NY – civic association 13 4 9 3 Yes Shooter fired 99 rounds in total – this would likelybeen reduced if his weapon capacity were 1/3 as large
Carthage, NC – nursing home 8 3 0 0 Yes Since shooter used multiple weapons and never reloaded, it’s unlikely capacity limits would have mattered.
Henderson, KY – Atlantis Plastics 5 1 0 0 Yes Shooter did not use a high capacity weapon
Dekalb, IL – Northern Illinois University 5 17 5 17 Yes This incident’s casualty count is quite low because the shooter first fired with a very low capacity weapon, his 6-round shotgun – enabling many students to escape the classroom. Shooter also had a long, documented mental health history.
Kirkwood, MO – City Council 6 1 0 0 Yes Shooter used low-capacity revolver initially, and took a higher capacity weapon from a victim (police officer).
Omaha, NE – Westroads Mall 8 4 5 3 No Shooter appears to have emptied one magazine and then taken his own life.
Crandon, WI – sheriff’s rampage 6 1 0 0 Yes Shooter used a service weapon, so proposed rules/limitations would have had no effect.
Blacksburg, VA – Va. Tech 32 23 32 23 Yes Shooter reloaded many times, and used multiple weapons. Mental health check would have prevented weapons acquisition.
Salt Lake City, UT – Trolley Square 5 4 5 4 Yes Shooter did not use high capacity weapons
Nickel Mines, PA – Amish School 5 5 2 2 Yes Once shooter started firing, sheriffs approached – he killed himself as they arrived, and likely would not have had a chance to reload.
Seattle, WA – Capitol Hill 6 2 6 2 Yes Shooter had a weapons-related felony charge, which was reduced to a misdemeanor.
Goleta, CA – postal shooting 6 0 6 0 Yes Shooter had a previous history of mental illness
Red Lake, MN – high school 9 5 3 2 Yes Shooter possessed a gun in his bedroom despite being treated with Prozac. Since he was an adolescent, and his parents/guardians chose to give him a gun, background checks would be ineffective. Shooter shot his grandfather who was a police officer, and took his weapons.
Brookfield, WIChurch group 7 4 2 1 Yes Shooter suffered depression, but had no mental health or criminal records.
Columbus, OH – concert 4 7 0 0 Yes No HCM used, and no medical or criminal record. Nearby police stormed the concert and shot suspect
Meridian, MS – Lockheed Martin 8 7 4 3 Yes Shooter used military-style weapon with high-capacity
Melrose Park, IL – Navistar 4 4 4 4 Yes Shooter used military-style weapon with high-capacity, and was also a convicted felon
Wakefield, MA 7 0 5 0 Yes Shooter used high-capacity weapon and also had a history of mental illness, but with the mental illness far in his past and no criminal record, even stringent checks might not have denied him weapons. Shooter stopped firing at an arbitrary point and sat calmly til arrested. If he had lower capacity weapons, stopping to reload multiple times might have caused him to sit and wait for arrest earlier.
Tampa, FL – hotel 5 3 5 3 Yes Shooter was arrested for assault only a few months earlier, and bought weapon at a gun dealer
Honululu, HI – Xerox 7 0 3 0 Yes Shooter acquired a large number of weapons long before mental issues began.
Fort Worth, TX – Wedgwood Baptist Church 7 7 2 2 Yes Shooter committed suicide after emptying three magazines – but he had six more loaded. Has the magazines been 1/3 smaller, that would have lowered the toll proportionally.
Atlanta, GA – Day trading 9 13 0 0 Yes The shootings happened in multiple separate incidents, making it less likely that HCM limits would have had an impact. Barton was suspected but never charged in earlier murders, so background checks would have had no impact.
Littleton, CO – Columbine High 13 21 6 10 No Shooters used a high capacity Tec-9 and standard capacity 9mm, so avg capacity is used here. Details of the shooting indicate that in many cases shooters fired at the same victim multiple times – if limited in capacity, this would have reduced their ability to fire on additional victims.
Springfield, OR – Thurston High 2 24 1 19 Yes Shooter was tackled and stopped when he first tried to reload – a clear indication that lower capacity would have further limited casualties.
Jonesboro, AR – Westside Middle School 5 10 2 3 Yes Shooters ran away after firing 30 rounds – lower capacity might have reduced total rounds fired.
Newington, CT – Lottery worker 4 0 0 0 Yes Shooter chose specific victims and fired relatively few rounds, so capacity limits make no difference here.
Orange, CA – Caltrans 4 2 3 1 Yes Shooter entered shootout with police shortly after initial incident, lower capacity might have shortened his attack
Aiken, SC – RE Phelon Co 4 3 0 0 No Standard capacity weapon (illegally acquired) used
Fort Lauderdale, FL – city employee 5 1 0 0 Yes Standard capacity weapon used
Corpus Christi, TX – Walter Rossler Co 5 0 0 0 Yes Standard capacity weapon used
Fairchild AFB, WA – hospital 5 22 5 22 Yes Shooter possessed only one 75 round drum magazine – so he would never have to reload. Military police arrived quickly and killed perpetrator.
Aurora, CO – Chuck E Cheese 5 0 0 0 No Shooter fired less than 10 times, executing each victim, usually with a single shot
Garden City, NY – LIRR 6 19 2 6 Yes Shooter emptied two 15 round magazines and was tackled while reloading with a third magazine. Total rounds fired would have been decreased by 1/3 were magazine capacity limits in place.
Fayetteville, NC – Luigi’s Restaurant 4 6 2 3 Yes Shooter used a high capacity rifle, shooting was stopped by nearby police
San Francisco, CA – 101 California St office building 8 6 4 3 Yes Shooter used a 32 round Tec-9 in the shooting, and fired hundreds of rounds
Watkins Glen, NY – office 4 0 0 0 Yes Shooter killed four intentional targets with relatively few shots, and then waited for police to arrive – perhaps less than 10 shots total fired.
Olivehurst, CA – Lindhurst High School 4 10 0 0 Yes Shooter used two weapons and fired relatively few shots, so high capacity weapon limits would have no effect here. Shooter also had no prior criminal or mental history.
Royal Oak, MI – postal 4 6 4 6 Yes Shooter had his concealed weapons permit revoked on concern of mental illness. Shooter also used high-capacity magazines with his rifle and fired scores of rounds according to police.
Iowa City, IA – Univ of Iowa 5 1 0 0 Yes Did not use a high-capacity weapon, and did not display sufficient signs of mental illness prior to shooting to warrant attention
Killeen, TX – Luby’s Cafeteria 20 24 8 10 Yes Used high capacity pistols and reloaded multiple times – capacity limits would have enabled more victims to escape, as many escaped by exiting the restaurant.
Jacksonville, FL – GMAC plant 9 4 9 4 Yes Shooter had a history of violence and convictions, and yet legally purchased multiple weapons. Used a high capacity weapon in shooting
Louisville, KY – Standard Gravure Co 8 12 8 12 Yes Shooter used high capacity weapon, emptying its magazine and committing suicide with his second weapon. Shooter also had a lengthy psychiatric history including hospitalization
Stockton, CA – schoolyard 5 29 5 29 Yes Shooter had a lengthy arrest history and had served time in jail as an accomplice to armed robbery, and yet was allowed to buy weapons.
Sunnyvale, CA – ESL Co shooting 7 4 7 4 Yes Shooter was able to purchase guns while under a court restraining order
Palm Bay, FL – shopping center 6 14 6 14 Yes Shooter used a high capacity .223 caliber rifle, and killed two police officers during the shooting – one of them as the officer was trying to reload. Perhaps if the shooter’s capacity were lower, the officer might have himself fared better. Gunman also had prior assault conviction.
Edmond, OK – USPS 14 6 0 0 Yes Shooter was in National Guard and would have had access to weapons. Though he was referred to as “Crazy Pat”, he had no history of crime or treated mental illness
San Ysidro, CA – McDonalds 21 19 14 13 Yes Shooter used a high capacity weapon, Uzi, pinning down a quick-responding officer with 30 rounds of fire before re-entering restaurant
Dallas, TX – nightclub 6 1 0 0 Yes Shooter used an unknown handgun, emptying it into crowd and then rushing out – unclear that capacity limit would have any impact here.
Miami, FL – welding shop 8 3 8 3 Yes Shooter did not use a high capacity weapon, but purchased his weapons one day after failing a psychiatric exam ordered by his employer, the school district, and after incidents in which he appeared to be a threat to students
Birchwood, WI – hunting altercation 6 2 3 1 Yes Shooter fired 20 rounds at other hunters – if he had a lower capacity, it’s likely that another hunter would have been able to respond with fire

The analysis above attempts to answer the question – what would have happened in these incidents had the proposed laws been in place? Of 459 deaths and 481 injuries in 63 shootings, I estimate that 250 deaths and 324 injuries (54% of deaths and 67% of injuries) might have been prevented with the analyzed proposals. Each proposal, its method of action, and the analysis approach is described further below.

High-Capacity Magazine Ban:

Definition: Sales of high-capacity magazines to and between private citizens would be completely banned, and imports of high-capacity magazines for private use would be banned as well. While many magazines would exist in private hands, a magazine buyback could then be used effectively, as magazines are relatively inexpensive.

Method of Action:

  1. In some instances, the shooter was disarmed by potential victims while trying to reload – smaller magazine size clearly would have limited total impact in these shootings.
  2. In some instances, potential victims fled during breaks in the shooting enabled by reloading – if a shooter has to reload 2 or 3 times as often, this effect is multiplied.
  3. In some instances, law enforcement arrived relatively quickly, and most damage in the shooting was done via the initial magazine – a smaller magazine would have limited impact in the shooting in these instances.
  4. In a few instances, victims attempted to rush the shooter immediately. If a shooter could only fire 10 shots instead of 20-50, it’s possible that he might be tackled quickly rather than be able to continue shooting.
  5. In most instances, the shooter committed suicide after doing a certain amount of shooting, but always before exhausting ammunition. Since each reloading represents a break in the act, some shooters would commit suicide after having fired fewer total rounds if they were capacity constrained.
  6. In a few instances, the shooter appeared to choose a specific weapon because of its high capacity. If high capacity magazines were not available, would the shooter still go forward with the attack?
  7. In 18 of 63 shootings, shooters fired relatively few rounds, chose a small number of specific victims, or used standard capacity weapons. In these instances the high-capacity magazine ban has no impact. 29% of actual mass shootings fell into this category.

Analysis Method: If the shooting fell into the last category above, then zero impact is noted in the analysis. Otherwise, the casualty count is reduced by the ratio of the shooter’s magazine size to standard magazine size – if the shooter used a 30 round magazine, then the casualty count is estimated at 2/3ds lower (rounded up) with a standard capacity magazine. This approach will tend to underestimate the effect of a ban in instances like 1,4, and 6 above, while providing an accurate estimate or an overestimate in instances like 2, 3, and 5 above. In aggregate, I think this approach is unbiased.

Stringent Background Checks:

Definition: Create a mandatory national database of all felons, mentally ill, and others posing threats (anti-terror lists, those who have made threats against schools or other institutions). Mandate that all firearms transactions for new and used weapons, in public and private transactions, be checked against this database, with instant results. This stands in contrast to the current background check system, which is done on paper and via telephone call, not electronically.

Method of Action:

  1. Out of 63 mass shootings over the past 30 years, only 5 have involved illegally purchased weapons. Some of the shooters had a history of mental illness or a criminal record – preventing a sale of firearms to these individuals would reduce the frequency of shootings.
  2. Many of the shooters with a history of mental illness had no criminal record – it’s unlikely that they would know how to obtain an illegal firearm.
  3. Some of the shooters purchased weapons in the days after making threats against a school or other institution – in these cases, a properly implemented stringent background check system would have prevented the weapon sales.

Analysis Method: Shootings were identified in which a shooter had a documented history of mental illness, a criminal record, or had made threats against an institution prior to buying a weapon. In these cases (17 instances total) it’s assumed that the casualty count is reduced to 0, as the shooter would have been unable to obtain a weapon. In reality a certain number of shooters would then try to acquire weapons illegally, and some might succeed. But a certain number of mentally-ill or former felons might never try to obtain a weapon if they knew they had no easy or legal means to do so, providing an offset.

Analysis of Assault Weapons Ban and Armed Civilian Presence

Two other proposals have been mentioned in the last several months – a ban on assault weapons and the placement of more armed guards or civilians in public places. On the question of assault weapons, the data from mass shootings shows that shooters preferred a range of semi-automatic weapons with high-capacity magazines. Weapon capacity makes a difference, but the type of weapon (handgun vs rifle) does not.

With regard to armed bystanders, in 9 of 63 shootings armed individuals (often police officers) were present. In several cases armed individuals became victims in the shooting, and the presence of armed individuals did not prevent the shooting from taking place. However, this analysis is by definition incomplete – this is an analysis of shootings that actually did take place, and doesn’t include data on shootings that were stopped by armed individuals. The evidence here suggests that the element of surprise may render concealed weapons somewhat ineffective, but this is not a conclusive finding.

The Simple Arithmetic of High Capacity Gun Magazines

In the wake of yet another mass shooting tragedy today, let’s examine the costs and benefits of high capacity gun magazines. I previously examined the cost-benefit of private gun ownership in the US, and noted at that time that the extraordinarily negative cost-benefit ratio might eventually become an issue for the pro-gun lobby (the industry generates economy-wide economic losses of over $15B/year) [1].

High capacity magazines [2] seem to have become a feature of virtually every recent mass-shooting in the US [3]. How many lives might have been saved by eliminating high-capacity magazines? Let us conservatively assume 10 deaths per year might be reduced through this policy (a rounding error compared to the roughly 10,000 annual gun homicides in the US). The economic value of 10 lives can be estimated at $80 million, while the annual sales revenue of high-capacity magazines might be less than $20 million (since gun magazine sales are a tiny fraction of gun sales, and magazines can be had for as little as $15) [4].

Measuring tragedy on an economic basis might seem crass, but it helps establish a key point: not only are high capacity magazines empowering individuals in mass shootings – but they are also provably hurting America as a whole, as they subtract value from our nation! An outright ban on possession of high capacity magazines is thus a reasonable step to limit further damage to America’s citizens and economy.

Let me address a number of potential criticisms here:

  • Would-be mass shooters will acquire weapons and high-capacity magazines illegally, so you are only affecting law abiding citizens. Actually, 75% of weapons used in mass shootings were acquired legally, and recent shooters acquired their weapons legally. Most of these shooters had no previous criminal record, so in the event high-capacity magazines were illegal, it’s unlikely that they would even know how to find them illegally.
  • Banning high-capacity magazines would have no effect on death rates, as shooters would simply reload. In the Gabrielle Giffords shooting, the gunman was stopped in his rampage once he stopped to reload. Reducing magazine capacity to 10 rounds reduces total firing capacity – this is simple arithmetic. In both of these shootings and many other incidents, lives would have been saved. For that matter, lives might be saved in incidents like drive-by shootings where the rapid fire of multiple rounds makes victims of innocent bystanders.
  • High capacity magazines are needed for self-defense. Even the police rarely find need to fire large numbers of rounds. Is there even one documented case of self defense where the potential victim needed more than 10 rounds to deter his attackers? There are outliers in everything, but I’d be surprised to hear of such a case.
  • I have a 2nd-Amendment right to whatever capacity magazine I like. The recent Supreme Court case upholding an individual right to a firearm also upheld the right to ban American citizens’ access to fully automatic weapons, grenades, tanks, and all other manner of military weapons. Even Justice Scalia admits that there are restrictions on the 2nd Amendment. Your right to purchase whatever weapon you like has long since been curtailed, and the government retains the right to enact reasonable restrictions on access to arms.


[1] Using more recent numbers on the economic value of human life at $8M per life, the gun industry may actually cause annual economic losses in the US of $200B per year (8M * 30k lives lost – economic value of gun trade). I republished the more conservative estimate above to remain consistent with the original analysis that I referenced.

[2] I am defining high-capacity magazines as those holding more than 10 rounds, as defined in the original assault weapons ban.

[3] Limiting gun capacity would have reduced casualties in a number of recent tragedies:

[4] Gun sales are estimated to have reached an annual rate around 12 million this year. If separate high-capacity magazine sales are in the neighborhood of 10% of all gun sales, and magazines cost around $15, then total annual revenue from this business might be 1.2M * 15 = $18M. This is an imprecise estimate, since gun sales are not tracked, but conveys the order of magnitude, and illustrates the tiny economic benefit supplied by this particular product relative to its cost in human life.

The True Cost of Gun Ownership

The gun industry generates a total economic loss of $15B per year in the United States.

Guns are a part of American culture, and guns are also a part of the economy in the US. While not a large industry, the small arms and hunting industries contribute roughly $29B annually to the US economy [1]. While many industries have externalities (think pollution), the gun industry’s externalities are particularly damaging: 31,000 deaths and 70,000 injuries per year [2].  From an economic standpoint, the cost-benefit of US gun ownership and the gun industry can be measured by weighing the economic benefit of the gun industry against the economic loss caused by premature deaths and injuries.

What is the annual economic loss associated with 31,000 deaths and 70,000 injuries? By looking at loss of income alone, each gun death can be valued at roughly $1.4M, or $43 Billion in total lost income [3]. A 1994 study published in JAMA concluded that medical costs from gun injuries cost another $2.3B, or $4B today including inflation [4]. The total economic costs of $47 Billion per year from gun industry externalities thus greatly exceed the economic benefit of the industry!

Perhaps this is not surprising. Guns were invented as military weapons, and while hunting and recreation are part of today’s industry, guns’ primary use remains human combat. In the 20th century, the arms industry split into two industries: a hugely profitable defense industry which sells only to the government, and a tiny small arms industry accessible to ordinary American citizens. Despite causing a $15B loss every year to the American economy, the American small arms industry exists because it is protected from its liabilities by the Second Amendment and its political allies.

Can this situation can be improved? The gun industry has thus far successfully resisted efforts at further regulation, and the NRA and other organizations have created a potent political alliance to prevent a change in the status quo. Eventually, an industry with huge negative externalities has to improve its behavior as attitudes shift, or public sentiment and politicians will force the issue (the oil and tobacco industries come to mind). The gun industry would do well to cooperate with reasonable regulations that decrease its negative side effects, or it risks harsher regulations down the road.

[1] The gun industry’s estimated total value in 1999 was $24B, or $29B today when adjusted for inflation.

[2] According to the CDC, there were roughly 31,000 deaths involving firearms (including homicides, suicides, and accidents), and  70,000 non-fatal injuries related to guns annually.

[3] Gun death rates peek in the 18-24 age range, and fall sharply after 30, according to the CDC (select Age under Output Group). Assume that the average person killed by a gun loses 35 years of productive life (from 35-70) . 35 years * US per capita income of roughly $40,000 equals $1.4 Million per person. No NPV adjustment is needed, because gun deaths are cumulative over time – last year’s gun deaths contribute to this year’s losses as well.

[4] This study concludes that the medical costs associated with firearms injuries were roughly $2.3B per year in 1994. Assuming a health care rate of inflation of 4% over the last 15 years (lower than the real rate!), this $2.3B equals $4B in 2009 dollars.