A needle gun commonly refers to a compressed air or gas-operated tool that is used to shoot nails, pins or staples through a surface. It is a powerful tool but has several synonyms in addition to nail gun, such as brad gun, finish nailer, stapler and pin gun. A brad gun is a common term used for small nails, while a finish nailer is used for larger nails primarily. On the other hand, a stapler is used for fastening objects like paper, and a pin gun is used for materials like fabric. All these synonyms are used for tools that employ similar compressed air or gas pressure to power them.