The Future of Children, Princeton - Brookings: Providing research and analysis to promote effective policies and programs for children.

Safety Devices Currently in Use

In comparison to many other products, guns have changed relatively little in their design over the past century. Major design changes have included a move from revolvers to pistols, an increase in caliber, and an increase in ammunition capacity.¹³ (See the article by Wintemute in this journal issue.) Most of these changes have resulted in the increased lethality of guns. With more bullets able to be discharged in a given period of time, and with higher-caliber bullets transferring greater amounts of kinetic energy to what they strike, the amount of human damage resulting from a shooting has increased. Studies of shooting victims seen in emergency departments, for example, demonstrate that the number of bullet wounds per person is increasing.¹⁴

Devices can be placed on guns to decrease the chances of unintended firings, however, thereby making the gun a safer consumer product. Although patents for these devices were granted in the early twentieth century, the devices are found on only a small percentage of guns in the marketplace today.¹⁵ Two of these devices are loaded chamber indicators and magazine disconnect safeties.

Loaded Chamber Indicators

Much like a camera informs its user that there is film in the camera, a gun can inform the user that there is a bullet in the gun. Principally for use in pistols (as opposed to in revolvers), a loaded chamber indicator alerts the possessor of the gun that the gun is loaded and can be discharged. The device is most often a small, cylindrical piece of metal that protrudes from the body of the gun if a round is in the chamber.

It is not intuitive to the person holding a gun, however, that the protrusion of the loaded chamber indicator indicates the loaded status of the gun. Nor is the position, size, coloring, or any other aspect of the loaded chamber indicator standard across makes and models of pistols.

The low prevalence of loaded chamber indicators on pistols, their lack of imparting a clear message to the person holding the gun, and their lack of uniformity all likely contribute to deaths that occur when the person later claims, "I didn't know the gun was loaded."¹⁵ More meaningful loaded chamber indicators could be designed and their inclusion on guns mandated through regulation.

Magazine Disconnect Devices

Another safety device that could reduce the likelihood of unintentional firearm deaths, the magazine disconnect device, is also used in pistols. These guns contain their ammunition in a magazine, or a clip, that fits into the pistol's handle. Even if the magazine or clip containing the ammunition is removed from the gun, however, the pistol may still have a "round in the chamber," or a bullet that remains in the gun ready to be fired. This danger is not well understood by the public. In a poll conducted for The Johns Hopkins Center for Gun Policy and Research, a representative sample of the U.S. population was asked if a pistol could be fired when the magazine was removed; 35% either didn't know that the gun could be fired or thought that it could not be fired.¹⁵ A magazine disconnect device physically prevents a gun from being discharged if the magazine has been taken out, even if the chamber still has a round in it.

Because the round in the chamber was recognized early on as an inherent safety problem, this device has existed on a small number of guns for many years. In 1911, a patent was issued for a magazine disconnect device.¹⁶ More recently, a patent application by an inventor named Frank S. Thomas stated,

It is well known to those familiar with conventional semi-automatic firearms that a live round left in the chamber after the magazine has been removed from its receiver poses a great danger to those who may handle or be exposed to the seemingly unloaded weapon. In the hands of the young, the inexperienced, the careless, a pull of the trigger may fire the "unhappy bullet" in whatever direction the weapon happens to be pointing.¹⁷

Notwithstanding the recognized need for this safety device and its clear technological feasibility, magazine disconnect devices are present on only about 14% of pistol models.¹⁵