As a caveat, treat ALL fixed ammunition, regardless of age or visual condition as if it had just been loaded.
Two anecdotes: A family owned a FLINTLOCK and someone decided to dribble a little powder in the pan and touch it off. They did, killing a family member with a ancient charge and ball that had lain quiet all those decades.
In a second less extreme, but satisfying case: A burglar found the WW2 1911 owned by a retired marine. He tried to shoot the owner, but the vintage hardball didn't fire. He was looking DOWN THE BAREEL when that 50 y/o primer said 'oh, is it time?'