A Solder gun is also known frequently as a soldering iron, though in truth a solder gun is really a particular type of soldering iron. A solder gun is among the largest of the soldering iron types and has a pistol shape. It is used in electrical wiring work to join materials, usually wires, together using solder. Solder is a lead tin alloy that has a fairly low melting temperature and good corrosion resistance properties.
The solder gun has a trigger, which when activated allows the working end of the iron or gun to get hot. This hot tip is then placed in contact with the material to be joined together. The material is now allowed to get hot and then solder is added. The solder is a solid at room temperature but will flow like a liquid when the temperature is elevated by the solder gun. The solder will flow amongst the materials to be joined and coat it evenly if done properly. The solder gun is then removed and the solder is allowed to cool. Once cool, the joint should be mechanically and electrically sound and last for a very long time.
Solder guns come in different sizes and temperature ratings. Since even the smallest solder gun is still quite large, for very delicate work, a pencil shaped soldering iron is more appropriate. Use a solder gun for electrical work and a pencil shaped soldering iron for electronic work.
The temperature of the solder iron tip is also important. Solder comes in different compositions, and different compositions have different melting temperatures. The melting temperature of the solder should match the temperature rating of the soldering iron. With the recent push in many countries to remove lead from industrial materials, solder composition is changing so that less lead is used. As less lead is used the melting point of the solder increases. If you are thinking of purchasing a solder gun, you will want to be aware of this. You would not want to purchase a solder gun that will soon be obsolete.
Solder guns should not be used with copper plumbing. The solder used in copper plumbing is of a different composition than that used in electrical work. A suitable soldering iron or propane torch should be used when making soldered connections with copper plumbing.