<P> For American shot, a useful method for remembering the diameter of numbered shot in inches is simply to subtract the shot size from 17 . The resulting answer is the diameter of the shot in hundredths of an inch . For example, #2 shot gives 17 - 2 = 15, meaning that the diameter of #2 shot is 15 / 100 or 0.15 ". B shot is . 170 inches, and sizes go up in . 01 increments for BB and BBB sizes . </P> <P> In metric measurement, it is easy to remember that #5 shot is 3 mm; each number up or down represents a 0.25 mm change in diameter, so e.g. #7 shot is 2.5 mm . </P> <Table> <Tr> <Th> US Size </Th> <Th> EU Size </Th> <Th> SW Size </Th> <Th> UK Size </Th> <Th> AU Size </Th> <Th> Nominal diameter </Th> <Th_colspan="2"> Pellets per oz (28 g) </Th> <Th> Quantity per lb . </Th> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Th> Lead </Th> <Th> Steel </Th> <Td> </Td> </Tr> <Tr> <Td> FF </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 230" (5.84 mm) </Td> <Td> </Td> <Td> 35 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 220" (5.59 mm) </Td> <Td> 27 </Td> <Td> 39 </Td> <Td> </Td> </Tr> <Tr> <Td> TT </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 210" (5.33 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> AAA </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 205" (5.20 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> AAA </Td> <Td> </Td> <Td>. 203" (5.16 mm) </Td> <Td> 35 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> AAA </Td> <Td>. 200" (5.08 mm) </Td> <Td> 36 </Td> <Td> 53 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> AA </Td> <Td> </Td> <Td>. 191" (4.93 mm) </Td> <Td> 40 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> BBB </Td> <Td> AA </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 190" (4.83 mm) </Td> <Td> 44 </Td> <Td> 62 </Td> <Td> 550 </Td> </Tr> <Tr> <Td> BB </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 180" (4.57 mm) </Td> <Td> 50 </Td> <Td> 72 </Td> <Td> 650 </Td> </Tr> <Tr> <Td> Air Rifle </Td> <Td> BBBB or 2 / 0 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 177" (4.50 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 170" (4.32 mm) </Td> <Td> </Td> <Td> 86 </Td> <Td> </Td> </Tr> <Tr> <Td> No. 1 </Td> <Td> </Td> <Td> </Td> <Td> BB </Td> <Td> BB </Td> <Td>. 160" (4.06 mm) </Td> <Td> 72 </Td> <Td> 103 </Td> <Td> 925 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 1 </Td> <Td> 7 </Td> <Td> </Td> <Td> </Td> <Td>. 158" (4.00 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 2 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 150" (3.81 mm) </Td> <Td> 87 </Td> <Td> 125 </Td> <Td> 1120 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 2 </Td> <Td> 6 </Td> <Td> </Td> <Td> </Td> <Td>. 148" (3.75 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 3 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 140" (3.56 mm) </Td> <Td> 108 </Td> <Td> 158 </Td> <Td> 1370 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 3 </Td> <Td> 5 </Td> <Td> </Td> <Td> </Td> <Td>. 138" (3.50 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 2 </Td> <Td> No. 2 </Td> <Td>. 134" (3.40 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 4 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 130" (3.30 mm) </Td> <Td> 135 </Td> <Td> 192 </Td> <Td> 1720 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 4 </Td> <Td> </Td> <Td> No. 3 </Td> <Td> No. 3 </Td> <Td>. 128" (3.25 mm) </Td> <Td> 140 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 5 </Td> <Td> </Td> <Td> </Td> <Td> No. 4 </Td> <Td> No. 4 </Td> <Td>. 120" (3.05 mm) </Td> <Td> 170 </Td> <Td> 243 </Td> <Td> 2180 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 5 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 118" (3.00 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 6 </Td> <Td> </Td> <Td> </Td> <Td> No. 5 </Td> <Td> No. 5 </Td> <Td>. 110" (2.79 mm) </Td> <Td> 225 </Td> <Td> 315 </Td> <Td> 2850 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 6 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 108" (2.75 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 51⁄2 </Td> <Td> No. 51⁄2 </Td> <Td>. 107" (2.72 mm) </Td> <Td> 240 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 6 </Td> <Td> No. 6 </Td> <Td>. 102" (2.59 mm) </Td> <Td> 270 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 7 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 100" (2.54 mm) </Td> <Td> 291 </Td> <Td> 423 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> No. 7 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 098" (2.50 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> No. 71⁄2 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 094" (2.40 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 71⁄2 </Td> <Td> </Td> <Td> </Td> <Td> No. 7 </Td> <Td> No. 7 </Td> <Td>. 095" (2.41 mm) </Td> <Td> 350 </Td> <Td> 490 </Td> <Td> 3775 </Td> </Tr> <Tr> <Td> No. 8 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 71⁄2 </Td> <Td>. 090" (2.29 mm) </Td> <Td> 410 </Td> <Td> 686 </Td> <Td> 5150 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 8 </Td> <Td> 00 </Td> <Td> </Td> <Td> </Td> <Td>. 089" (2.25 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 8 </Td> <Td> No. 8 </Td> <Td>. 087" (2.21 mm) </Td> <Td> 472 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 81⁄2 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 085" (2.15 mm) </Td> <Td> 497 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> No. 81⁄2 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 083" (2.10 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 9 </Td> <Td> </Td> <Td> </Td> <Td> No. 9 </Td> <Td> No. 9 </Td> <Td>. 080" (2.03 mm) </Td> <Td> 585 </Td> <Td> 892 </Td> <Td> 7400 </Td> </Tr> <Tr> <Td> </Td> <Td> No. 9 </Td> <Td> 000 </Td> <Td> </Td> <Td> </Td> <Td>. 079" (2.00 mm) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> No. 10 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 070" (1.78 mm) </Td> <Td> 848 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No. 10 </Td> <Td> No. 10 </Td> <Td>. 070" (1.78 mm) </Td> <Td> 850 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> No. 10 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 069" (1.75 mm) </Td> <Td> </Td> <Td> </Td> </Tr> </Table> <Tr> <Th> US Size </Th> <Th> EU Size </Th> <Th> SW Size </Th> <Th> UK Size </Th> <Th> AU Size </Th> <Th> Nominal diameter </Th> <Th_colspan="2"> Pellets per oz (28 g) </Th> <Th> Quantity per lb . </Th> </Tr>

When did they start making 3 inch shotgun shells