The Penny Method of Removing Gun Rust.

Sometimes you come across a used gun with a shockingly low price tag and you just have to find out why. More often than not, it’s a light sheen and pockmarks of rust on the barrel that will be responsible for knocking some digits off the price, but that’s not necessarily a reason to put it back on the rack.

The video above shows you a time-honored method of removing rust that’s almost free and works very well. In fact, you might have seen an old-school gun guy do this at one time or another. The trick these days is finding a penny minted before 1982, which were 95 percent copper and 5 percent zinc.

To start, you need some light oil (good old 3-in-1 will do just fine), a medium brass-bristle cleaning brush, some paper towels, and your pre-1982 penny.

Pick a spot to start, put some oil on the metal, rub the penny over the area, and wipe clean with a paper towel. Repeat until the rust is gone. Use the brush to scour the rust out of areas with small crevices, like a shotgun rib.

The copper in the penny is softer than the steel, so light pressure will wear away the rust without scouring the steel or the remaining blueing. This is why choosing a penny made after 1982 will cause you some serious problems, as pennies then were made primarily of zinc, with only traces of copper.

You could use copper wool scouring pads as well, but keep in mind, they will break apart after some use. To get the $100 Rossi double-barrel looking good, the guy in the video spent about an hour working with the penny.

Of course there are other methods of varying effectiveness. If you have an extremely rusty gun, you could give this home electrolysis method a shot, provided you’re extra safe:

It’s definitely a DIY job, but the gun owner has some real success starting at the 7:00 mark. The method only requires some rebar, a car battery or jumper box, washing soda (which is sodium carbonate, not sodium bicarbonate, which is baking soda), and a container big enough to submerge everything in water.

Adding the electric current causes the molecules of the gun barrel that have turned from steel to iron oxide—rust—to flake off. The rust is then attracted to the less noble rebar with the current running through it, serving as the anode. It’s referred to as the sacrificial metal, since it sort of takes on the oxidation.

Here’s a good step-by-step electrolysis method to restore old tools that would work just fine on gun parts.

However, remember that any metal parts where the rust is removed will result in exposed bare steel, which can re-oxidize quickly. Be sure to oil everything down immediately. Electrolysis could also remove rust-bluing, so be aware of that too before starting a project.

Another method for mild rust is to simply soak the metal part in distilled white vinegar for a few days. As you can see in this video, it does a great job, but, again, plan on rebluing the barrels later, since vinegar will remove any old bluing that might be on there.