Imagine the sensation of firing a truly rapid fire rifle. Since each turn of the crank handle fires the rifle four times, it is capable of pulling the trigger many times faster than you can. The ATF has ruled this device is not regulated by federal law. Generally, the only visible element of the laser beam is a spot on a solid object that reflects light back to the operator. The beam itself is invisible in clear air.
All devices are simple to make and very inexpensive.
Only common material and hand tools required. Type Firepower From a Semi Auto Rifle. And you're probably wondering about the girls.