Oh, wise uncle PeaShooter, could you tell us about the development of the shotgun, specifically in context of the rounds fired and, even more specifically, around the time cartridges were being produced for other firearms? I'm mainly curious as to whether or not it took shotguns longer to get cartridges, and what the early ones looked like.
The oldest ancestor of the shotgun was the blunderbuss, which was popular in the 17th to early 18th century.
While the blunderbuss was awesome for combat, its had a very large chamber, which created a shot pattern that wasn’t tight enough for hunting fowl (ducks, geese, flying game). So people started taking regular military muskets, such as the Brown Bess or Charleville and loading them with birdshot.
This made sense as the calibers of muskets of the time, were large bore, .69 or .70 caliber. This equates to 16 gauge and 10-12 gauge respectively.
To load any kind of muzzleloader with birdshot, first the user inserts a charge of powder, then a wad, then the shot, and then caps it off with a piece of card.
As fowling became more popular, gunsmiths produced special sporting muskets called fowlers. Fowlers were lighter, had longer barrels, and easier to use against aerial targets.
Eventually they started making double barrel fowlers to give hunters an extra shot.
By the mid 19th century the caliber of muskets dropper from larger bores to smaller bores, usually around .50 to .58 caliber. In addition muskets were rifled with the advent of the minie ball. Despite the drop in caliber, people still demanded larger bore muzzleloaders to use as fowlers. It was at this point that the fowler became the shotgun, as gunsmiths produced firearms specifically to fire shot. Of course by them most shotguns were percussion.
The first shells adopted for the shotgun were pinfire and needlefire, around the 1840’s and 1850s. Of course, after the American Civil War, centerfire shotgun shells became popular. Most were made from thick paper of cardboard.
Around the late 19th and early 20th century brass shotgun shells would come into production. Plastic shells didn’t come about until the 1940’s or 1950’s