These short shoulder-stocked weapons with large bores and flared muzzels were mostly civilian arms. They found initial acceptance in the mid-1600's, and became more popular as growing overland travel increased highway banditry in the eighteenth century. Usually loaded with small shot, they were ideal for stopping a close group of men, or defending a door or stairway (although it has since been demonstrated that the size of the muzzle flare had little control of the shot pattern).
Their greatest military use was aboard ship, where the blunderbuss proved a handy weapon on crowded decks. The infantry, too, apparently employed limited numbers of them for such things as sentry duty, signaling, etc.
Many fortified locations of this period used a semi-shoulder firearm called the "wall" or "rampart" gun. It was usually a heavy-barreled, large-bore version (smooth or rifled) of a musket, which could carry across water or cleared land for considerable distances. Some were mounted on swivels, while others included metal studs underneath to hook over a parapet. Shorter types were also used, with many being mounted on ship decks or longboats.