In the wake of the Sandy Hook school shooting, the National Rifle Association proposed putting more guns in schools. After a racist shot up a Charleston prayer group, an NRA board member argued for more guns in church. And now predictably, politicians and gun rights advocates are calling for guns in movie theaters after a loner killed two people at a Louisiana theater.

But research shows that more guns lead to more gun homicides – not fewer. And that guns are rarely used in self-defense.

Researchers at Mount St. Mary’s University shed light on why people don’t often use guns in self-defense. Knowing when and how to apply lethal force in a potentially life-or-death situation is difficult.

The study was commissioned by the National Gun Victims Action Council, an advocacy group devoted to enacting “sensible gun laws.” The study found that proper training and education are key to successfully using a firearm in self-defense: “carrying a gun in public does not provide self-defense unless the carrier is properly trained and maintains their skill level,” the authors wrote in a statement.

They recruited 77 volunteers with varying levels of firearm experience and training, and had each of them participate in simulations of three different scenarios using the firearms training simulator at the Prince George’s County Police Department in Maryland. The first scenario involved a carjacking, the second an armed robbery in a convenience store, and the third a case of suspected larceny.

They found that, perhaps unsurprisingly, people without firearms training performed poorly in the scenarios. They didn’t take cover. They didn’t attempt to issue commands to their assailants. Their trigger fingers were either too itchy – they shot innocent bystanders or unarmed people, or not itchy enough – they didn’t shoot armed assailants until they were already being shot at.