the starter gun
The Arms Dealer stocks it as soon as he moves in, so for most runs it is the first gun you own without having to dig for one. It fires fast for something available that early and handles surface enemies and the first cave trips fine as long as you keep musket balls in the bank. It also falls off quickly. Anything from a shadow orb or crimson heart outclasses it, and the Minishark ends its career outright.
trivia
The sprite is a revolver in everything but name. It also fires far quicker than the musket it is supposedly the small sibling of, which is backwards from how the two compare in reality, where both are single shot and reload just as slowly.