Buck and ball was probably standard by the late 18th century. Prior to that, there were examples of multiple loads (I think often two balls). Shot was probably used more for hunting -- especially in a time when your opponent had a good chance of being armored.
Historically buckshot was used by guards, but I'm not sure how far back that goes.
There really wasn't the need for a dedicated "shot weapon" and I'm not aware of any until the late 17th century. As most weapons were smoothbore just pick one that gives you the right spread and go with it. A blunderbuss was a kind of coach-gun. The bell end to the barrel doesn't do anything for the spread of the shot, instead it facilitates loading on the back of a moving carriage. :-) They don't show up until the 18th century (maybe very late 17th).