Just saw a movie. Pierce Brosnan was ambushed while trapping in the high mountains with snow everywhere. Ended up rolling down the mountain loosing his rifle.

A little later he desperately needed to start a fire. Part of the lost gear was his flint and steel. He had just started a fire before the ambush. Explaining the loss.

He still had his cartridge belt and some ammo. Being set shortly after the civil war they were obiviously black powder.

Using his bowie he pried out the the bullet. Then somehow wedged the casing facing his tinder. I didn't really catch how. Then with his bowie and smacking the handle. He used the point as a firing pin to set off the cartridge.

Thus igniting the tinder.

Yes I know most of it was movie magic. Setting off the primer this way would be a real pita. But it might be another way to get a fire going. If you are desprate and have noting else available.