@ Point Blank

and

@ k/t

Found an article which clarified the historical issue for me:

At the beginning of the 16th century, the arquebus was considered a general-purpose firearm. It generally weighed ten pounds or less--no heavier than a modern assault rifle ... on the other hand, the musket was a much heavier weapon devised by Spanish gunsmiths to achieve greater penetration against both steel armor and the wooden planks of naval vessels ... "musket" was at first reserved specifically for a specialized type of heavy infantry firearm but eventually grew to encompass the general-purpose firearms as well
http://l-clausewitz.livejournal.com/221137.html