Algodoo

It's a musket, first shot is already loaded.
Pull the trigger to fire, then pull the hammer back (red lever) and remove the left over "gunpowder".
Put new gunpowder in, put a bullet in and ram it down all the way back with the ramrod.
Push the hammer back in and pull the trigger.

Hope you enjoy it, please rate or give a comment.

Edit: Made the hammer easier to move, made the bullet faster.