The basic unit of ammo for both the shotgun and the super shotgun is 4 shotgun shells (or eight at the I'm Too Young To Die and Nightmare! skill levels). They are scattered around the levels in all classic Doom games.
For gameplay considerations, the two shotguns use shells to unequal effect, and the shotgun operates differently for the player and the shotgun guy. When wielded by the monster, the shotgun produces only three pellets when fired, while in the hands of the player the weapon fires seven pellets per shell. Furthermore, the super shotgun fires a hefty twenty pellets, potentially causing nearly three times the damage the shotgun inflicts, while using only twice the ammunition.
The IWADs contain the following numbers of sets of 4 shotgun shells:
|Game||ITYTD and HNTR||HMP||UV and NM|
|The Ultimate Doom||288||294||290|
The shotgun shell pickup appears in Doom RPG. It gives the player either 4 or 10 shells.