Bronze, iron, steel: When you think of firearm manufacturing, chances are you're thinking of those metals and alloys. It's true that, since people have been manufacturing guns, the vast majority of them have been made from bronze, iron or steel. (These days, of course, the vast majority are manufactured with high-grade steel.) However, there are some strange metals used in gun manufacturing from time to time ... and it's entirely possible that you may not even know a couple of them exist! Get out your periodic table and get ready to learn about some very rare earth, indeed.
1) Cr: Chromium
Yes, that name is where the word "chrome" comes from, and it's definitely every bit as shiny as you'd hope. Additionally, Chromium is very resistant to corrosion, wear and heat. It has three common uses in gun production: First, as an alloying agent of steel and stainless steel; second, as an anti-corrosion plating on firearms; and third, as a wear-resistant plating in bores. Chromium is terrific for these uses because it's a very hard metal. It also has a very high melting point, and, interestingly, increases lubricity.
2) Nb: Niobium, also known as Columbium
This rare metal has all of the characteristics for making the perfect rifle barrel. It's easily machined, for starters. It is substantially more resistant to heat and corrosion than any type of stainless steel. It has terrific yield strength and modulus of elasticity. Like we said, perfect ... except for its scarcity, and, therefore, its very high cost. Because of those factors, Niobium/Columbium is usually only used for Gatling-type guns, where the price make sense in order to keep a full-auto firearm of that type safe from heat and corrosion.
3) Pt: Platinum
No doubt you'll recognize the name of this element, one of the most expensive metals used in jewelry. Due to that expense, it's primarily used today in the gun industry for decorative inlays and overlays—much as gold is used for many fine shotguns. But it wasn't always that way.
Back in the era of flintlocks, gun manufacturing was entirely done by hand. Some gunmakers noticed platinum's extreme resistance to corrosion and heat and used it in touch-holes of flintlock muzzleloaders. It was also used as an overlay in the flash pan. Today, platinum is still used ... although mostly in optics. Its extreme ductility makes it useful for optical sight reticles.
4: Sc: Scandium
Scandium is what's called a rare-earth metal. How rare? Well, it wasn't even discovered until 1879. In its pure form, it is relatively soft with a high melting point. When alloyed with aluminum, Scandium renders it considerably stronger than other aluminum alloys, more fatigue-resistant, virtually corrosion-proof, lighter and less expensive than titanium alloys. The resulting alloy is aerospace-quality. Lovers of small, lightweight CCW revolvers are most likely to encounter Scandium alloys in their firearms.
What other "weird" elements have been used in guns? Copper, gold, silver and nickel have all been part of gun manufacture for centuries as well!