About ear piercing guns :
In concept, a piercing gun is similar to a staple or nail gun. It uses force to push an object (the earring stud) into a surface (the ear). Most ear piercing guns are made from plastic and metals, and can be purchased without any special license or required training from beauty supply stores and manufacturers. Their use is widespread, and almost every mainstream ear piercing facility (Claire's, Merle Norman, Wal-Mart and beauty salon type places) uses them.
The way they work seems fairly simple: with an earring stud in place in the adapter, and a backing in the cradle, the tension regulator is pulled back or "cocked", the point of the stud is used as a guide for aim and the trigger is pulled, forcing the stud through the flesh. As of yet there are no widespread certifications or government regulated training requirements associated with the use of piercing guns. Doing this procedure is about as complicated as stapling a few sheets of paper together.