Some of the more common
"known" gauges are:
0 gauge 1 gauge 2 gauge 3 gauge (rarer) 4 gauge 8 gauge 10 gauge 11 gauge (rarer) 12 gauge
14 gauge 16 gauge 18 gauge (rarer) 20 gauge 24 gauge 28 gauge 32 gauge aka 14mm
410 gauge aka 36 gauge aka 12mm .310 Remington skeet .360 British 5mm Wingo 6mm (CF and Rimfire) 7mm (CF & RF) 9mm (CF&RF)