Sounds like you may have found a vintage cap pistol. Many were made of cast iron.
The most collectible ones had anti-Chinese or anti-Black phrases cast into the metal. Rather than search under regular firearms, try searching the net under vintage cap pistols.
And yes, pictures would be a great help. You may have found a real firearm, or it may be a cap pistol. Show us some photos, next to a ruler for scale, and get closeups of any markings and features.
If it's a cap pistol, it could be worth more than a cheap handgun of the same era.
"Therein do I see an ugly cat. Smoke. Fire. Brimstone. A vast desert. Holes in parchment. The ugly cat is much amused." --- The quantrains of Gatodamus (1503-1566)