MuzzleSafe™ (PATENT PENDING) is a proximity gun safety system that makes it very difficult to shoot oneself, and greatly reduces the likelihood of accidentally shooting someone else. It is intended for training and target shooting applications; not for self-defense.
The concept is simple. Using a proximity sensor (a.k.a. rangefinder), the device measures the distance between the firearm's muzzle, and the object likely to be struck by the bullet if the firearm is discharged. This information is fed to a microcontroller, which makes a decision to either allow or disallow fire.
In the proof-of-concept prototype, the proximity sensor is an ultrasonic sonar rangefinder, and the "firearm" (airgun) is enabled and disabled using an electromechanical relay switched by a transistor. The response time is somewhere in the neighborhood of 50 milliseconds (1/20th of a second). This is much faster than any human reflex arc, and makes it nearly impossible for a person to shoot themselves; even deliberately.
MuzzleSafe™ allows for several modes of operation: The first and foremost is disabling fire when an object is considered to be too close to the muzzle. This is useful for several reasons, from nearly eliminating the risk of shooting oneself, to greatly reducing the risk of accidentally shooting someone else. Through mathematical models and CAD simulations, it was discovered that the chances of a stray bullet hitting a person increase dramatically with that person's proximity to the muzzle of the gun at the moment it fires. By disabling fire in the "point blank" regime, MuzzleSafe™ protects innocent bystanders while still facilitating normal target practice.
The CAD files, spreadsheet, OpenSCAD script, etc. involved in creating the above are all available on Thingiverse!
Other programmable modes include the ability to prevent firing on targets that are too far away (this includes shooting up in the air, which can be dangerous), and only firing on targets that lie within (or outside of) specified range intervals.
Again, MuzzleSafe™ is intended for target shooting, competition, hunting, and training new shooters; not for self-defense applications! Voluntary adoption of MuzzleSafe™ firearms by law enforcement, military, and civilian firearms training facilities will drastically reduce accidents, suicides, and other undesired or negligent discharges. MuzzleSafe™ also provides a proverbial safety net for a child's first .22 rifle or airgun; severely reducing the risk of injury, while still allowing for supervised learning of proper firearm handling skills.
DISCLAIMER: All MuzzleSafe™ firearms and airguns should be treated as if they are ready to fire at all times. Like any safety device, MuzzleSafe™ should not be relied upon to prevent injury or death from accidental discharge. Proper muzzle control and trigger finger placement must be observed when handling any firearm. The creator of MuzzleSafe™ will not be held liable for injuries or deaths caused by negligence on the part of the end user. Use of any MuzzleSafe™ product shall signify acceptance of these terms, and of all liability stemming from the handling of any firearm or airgun. Demonstrations of the technology are conducted under controlled conditions and should not be attempted.