Loaded Flintlock - problem or not?

[CutlassCollector]

I recently purchased a flintlock sea service pistol which I found is still loaded. I usually stick to edged weapons so I am unsure about this.
I doubt that it is still possible to discharge after all this time but I'd rather be safe than sorry.
So how frequent does this happen and what is the normal procedure? How do you remove the charge, the top wad came out easy but the ball seems firmly stuck. What is the best way to unload?
Any advice appreciated. Thanks.
CC