This is probably not actually a "complete" list as there have been so many variations produced all over the world. Please leave a comment if we are missing something. This list includes shotgun rounds only.
Please see our other lists for handgun, rifle, and rimfire ammo.
.410 Brass Obsolete Shell
1 to 3 Gauge Obsolete Cartridge
10 Gauge Shell
10 Gauge Brass Obsolete Cartridge
10 Gauge Pinfire Obsolete Cartridge
11 Gauge Obsolete Cartridge
11.15x52mm (Brass) Obsolete Cartridge
12 Gauge Current Cartridge
12 Gauge Brass Cartridge
12 Gauge Pinfire Obsolete Cartridge
14 Gauge Obsolete Cartridge
14 Gauge Pinfire Obsolete Cartridge
14mm Pinfire, Calibre 32 Lefaucheux / Cal. 32 de espiga / 32 cal. a broche / 32 gauge pinfire / 14 mm de espiga / ECRA-ECDV 14 063 CBP 850 Obsolete Cartridge
15 Gauge Obsolete Cartridge
16 Gauge Shell
16 Gauge Brass Obsolete Cartridge
16 Gauge Pinfire Obsolete Cartridge
18 Gauge Obsolete Cartridge
18 Gauge Pinfire Obsolete Cartridge
20 Caliber Wingo (0.200 Bore, 582 gauge) Obsolete Cartridge
20 Gauge Brass Obsolete Cartridge
20 Gauge Pinfire Obsolete Cartridge
20 Gauge slug Shell
24 Gauge Obsolete Cartridge
24 Gauge Brass Obsolete Cartridge
24 Gauge Pinfire Obsolete Cartridge
28 Gauge Shell
28 Gauge Brass Obsolete Shell
28 Gauge Pinfire Obsolete Cartridge
310 Remington (Brass Obsolete Cartridge
32 Gauge Obsolete Cartridge
32 Rimfire (0.320, 142 Gauge Obsolete Cartridge
360 Centerfire (99 Gauge) Obsolete Cartridge
4 Gauge Obsolete Cartridge
4 Gauge Brass or Pinfire Obsolete Cartridge
410 Bore (68 Gauge) Cartridge
410 Paper Cartridge
44 Mag shot Obsolete Cartridge
44 XL (1 9/16 inch) Obsolete Cartridge
55 Maynard 1865 (Brass) Obsolete Cartridge
64 Maynard (Brass) Obsolete Cartridge
6mm, (0.236 Bore, 353 gauge) Obsolete Cartridge
7mm, (0.276 Bore, 223 gauge) Obsolete Cartridge
8 Gauge Obsolete Cartridge
9.1x40mm (0.358 Bore, 101 Gauge) Obsolete Cartridge
9mm Centerfire Obsolete Cartridge
9mm Rimfire Shell
9mm Rimfire Brass Obsolete Cartridge
Collath Gauges (various gauges) Obsolete Cartridge
Greener 12-14 Police Gun Mk III/ 18.8x72.5 R / ECRA-ECDV 19 072 BBC 850 Obsolete Cartridge