Before the cartridge era, circa 1870 or so, it was very common to discharge your muzzle loader in order to clean it. I even have comments that my great-grandfather wrote in his Civil War diary about firing his rifle so that it could be cleaned due to concerns of the powder getting damp in the barrel in humid conditions.
I have been shooting muzzle loaders for over 45 years, pistol, rifle, and shotgun, and firing my flintlock rifle into a dirt burm is the easiest, and safest, way to unload it.
You can leave a gun loaded with black powder for well over a 100 years and it will fire right off with no problem. Very stable powder.
Thanks Inyo-Mono. It was nice to hear of your great-grandfather, and your knowledge and history with these guns. Excellent. 100 years? That’s really something.
Take care bud.
A book on gun collecting that I picked up a few years back warns that any blackpowder arm newly found after many years (like in Grandpa’s attic) should always be regarded as loaded.