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Undergraduates' Invention Makes Handguns "Childproof"

May 15, 2000
Johns Hopkins University
A device that keeps young children from firing a handgun, without relying on electronic components, keys or combination locks, has been invented by undergraduate engineering students at Johns Hopkins In t tests, children up to age 7 could not defeat the child-proofing device. Adults, however, were able to move the weapon into firing mode within three seconds.

Inexpensive Device Could Prevent Accidental Shootings by Youngsters

A device that keeps young children from firing a handgun, without relying on electronic components, keys or combination locks, has been invented by undergraduate engineering students at The Johns Hopkins University. In pilot tests conducted by the students, children up to age 7 could not defeat the child-proofing device. Adults, however, were able to move the weapon into a firing mode within three seconds.

In an important added precaution, the device automatically switches the gun back to "safe" mode as soon as the weapon leaves the adult's hand. Unlike trigger guards, which usually require a key or combination and can be awkward to remove, the Johns Hopkins students' device works by covering and manipulating a pistol's existing safety lever. The students describe the mechanism as durable yet inexpensive. If gun manufacturers incorporated this childproofing device into their products, the inventors estimate it would increase a handgun's retail price by no more than $35.

Seniormechanical engineering majors Richard Glorioso, 21, of Baltimore, and Bryan Rydingsward, 22, of Canton, Conn., designed and built the safety device during a two-semester course in which students tackle real-world engineering assignments, working within maximum budgets of $6,000 to $8,000. (The students came in well below their budget, spending about $4,500.) Curt Ewing, a laboratory administrator for the university's Department of Mechanical Engineering, devised a crucial component to help return the gun to its "safe" mode when it leaves an adult's hand. The students and Ewing jointly have applied for a patent on the device and will seek to interest gun manufacturers in the invention.

The class project was launched last fall with funding and a challenge from the Center for Injury Research and Policy at The Johns Hopkins School of Hygiene and Public Health. "What they wanted was an inexpensive device that would childproof a handgun for children 6 years old and younger," Rydingsward said. "At that age, kids don't understand the magnitude of what handguns can do."

Seven years ago, students in this same Johns Hopkins class devised a crude electronic "smart gun" that could only be fired by its owner. University researchers challenged the industry to refine this idea, setting off an intense, continuing debate over the cost and reliability of high-tech handguns. For their childproofing device, however, Glorioso and Rydingsward took a "low-tech" approach, sticking with the simple springs and other mechanical parts that are already used in conventional handguns.

The student engineers designed a metal cover that could be fastened atop the barrel of a 9-mm semiautomatic pistol, covering the safety lever and forcing it into the position that prevents the gun from firing. When two buttons are depressed, the cover slides open, exposing the safety switch and allowing the user to put the gun into its "fire" mode. Small children lack the dexterity, finger strength and mental agility to open the sliding door, the students discovered during tests with young children. Yet these children's mothers had no trouble opening the cover, the inventors said. That was important, the students said, because adult gun owners want to be able to arm themselves quickly if they hear a home intruder at night. With minimal practice, Glorioso said, "you could open the cover and flip the safety lever with your eyes closed."

But what if the "intruder" turned out to be merely a noisy family pet, prompting the sleepy gun owner to set the weapon down on a night stand, where a child might later pick it up? As a secondary precaution, the engineering students, with help from Ewing, added another mechanism to the handle of the gun. As a result, when the grip is released, the cover automatically springs shut and returns the safety lever to its "safe" position.

"This device does the two main things we hoped it would do," said project sponsor Andrew E. Lincoln, assistant scientist at the Center for Injury Research and Policy. "First, it provides a means of protecting young children without inconveniencing the gun owner in terms of time or excessive cost. And second, it provides passive protection, meaning it doesn't require the adult to do anything other than put the gun down to re-activate the safety."

Lincoln added, "There is overwhelming public support for making guns more childproof. Despite that kind of support, the manufacturers haven't responded. So this project had a limited scope and a specific purpose: We wanted to show that a device like this could be designed and built over an eight-month period. The students proved it could be done."

The childproof gun was one of 11 Johns Hopkins projects completed this year by undergraduates in the Whiting School of Engineering's Design Project course taught by Andrew F. Conn, a Johns Hopkins graduate with more than 25 years of experience in public and private research and development. Each team of two or three students, working within budgets of up to $8,000, had to design a device, purchase or fabricate the parts, and assemble the final product. Corporations, government agencies and nonprofit groups provided the assignments and funding.

Reporters, editors: Color slides of students and their childproof gun device available; see images and contact Phil Sneiderman


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Materials provided by Johns Hopkins University. Note: Content may be edited for style and length.

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Johns Hopkins University. "Undergraduates' Invention Makes Handguns "Childproof"." ScienceDaily. ScienceDaily, 15 May 2000. <>.
Johns Hopkins University. (2000, May 15). Undergraduates' Invention Makes Handguns "Childproof". ScienceDaily. Retrieved June 14, 2024 from
Johns Hopkins University. "Undergraduates' Invention Makes Handguns "Childproof"." ScienceDaily. (accessed June 14, 2024).

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