Hi, Ben, I use the automotive de-greaser SuperClean to strip paint from metal figures. You can find it at WalMart for eight bucks and change for a gallon. It used to be made by Castrol, and you might also find it at automotive supply stores like AutoZone.
I like it because it can be used in batches, over and over again. I use glass jars of various sizes to soak the pieces. After about 5 minutes, the paint is often softened and dissolving into the solution. The longer the soak, the more the paint dissolves and softens. I use an old toothbrush then to scrub the softened paint away gently, rinsing under the tap.
Some people use oven cleaner. I used to use that, too, but it has drawbacks. One is that it's once-and-done, that is, you spray a figure with oven cleaner, let it work, then rinse it off and that batch is gone. Another is that it's very caustic-its active ingredient is lye. You need to work in a well-ventilated area, and gloves are also a good idea.
SuperClean also has lye in it, but it doesn't seem to be nearly as caustic. It's still a good idea to work with ventilation, and gloves, but I don't usually use them with SuperClean.
And it has household uses, too, for cleaning grease, etc. That appeals to my sense of frugality. And it can be used with metal, resin, or styrene.
Hope that helps!
Prost!
Brad