Depending on what you call guns and why you want to know. If you make a modern revolver out of gunmetal you will die when you pull the trigger - those guns were black powder cannons, not rifles. As the others have said, all the important parts, including barrels, are made of steel.
Red brass which is a type of bronze, an alloy of copper (88%), tin (10%), and zinc (2%) called GunMetal.
This is basically used to make guns worldwide.
Different types include steel, stainless steel, titanium, aluminum
All of the pressure-holding parts of a gun, from the bolt, breach, barrel, etc are made of steel. Many of the other parts can be made of different materials. Grips on revolvers are wood or ceramic or ABS plastic. Many contemporary semi-auto pistols have a polymer frame, with steel barrel, slide, etc.
Stainless steel is typically used.
The frame may be done from various types of steel, aluminium (7xxx or 8xxx series), plastic or carbon fiber.
The barell is usually made from stainless steel (AISI 416) or carbon steel (AISI 4140)
You can google for specific ingredients now.
Alloy mrtal with indegrients that a gun is made of
