<P> The British system is based on the amount of shot per ounce . The sizes are LG (Large Grape - from grape shot derived from musket shooting), MG (Medium Grape), and SG (Small Grape). For smaller game SSG shot is half the weight of SG, SSSG shot is half the weight of SSG, SSSSG shot is half the weight of SSSG, and so on . The Australian system is similar except they have 00 - SG, a Small Game shell filled with #00 Buck . </P> <P> The most commonly produced buckshot shell is a 12 gauge, 00 buck shell that holds 8 pellets . Buckshot is generally used for two purposes: self - defense and hunting medium to large game . Loads can be tailored through altering the size of the shot, pellet count, length of the shell, powder charge, and in other ways to fit individual weapons and purposes . For instance, loads of 12 gauge 00 buck are commonly available in 8 to 18 pellets in vendor - stated lengths from 2 3 / 4" to 3 1 / 2 ". On packaging, vendors state the length of the cartridge as expanded after firing . Before firing, the crimped cartridge starts off approximately one half inch shorter . Also, precise length varies depending on manufacturer and model . Reduced - recoil shells are becoming increasingly available . Low - recoil 00 buckshot allows the shooter to make fast follow - up shots, which may be needed in a combat situation . They are also useful for training shooters who are not yet used to the recoil of full - power shells . </P> <Table> <Tr> <Th> US Size </Th> <Th> UK Size </Th> <Th> AU Size </Th> <Th> Nominal diameter </Th> <Th_colspan="2"> Pellets / oz (28 g) </Th> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Th> Lead </Th> <Th> Steel </Th> </Tr> <Tr> <Td> Tri-Ball 12 (12 Gauge) </Td> <Td> </Td> <Td> </Td> <Td> 0.60" (15.2 mm) </Td> <Td> 1.4 </Td> <Td> </Td> </Tr> <Tr> <Td> Tri-Ball 20 (20 Gauge) </Td> <Td> </Td> <Td> </Td> <Td> 0.52" (13.2 mm) </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> #0000 Buck <P> ("four - aught" or "quadruple - aught") </P> </Td> <Td> </Td> <Td> </Td> <Td>. 375" (9.525 mm) </Td> <Td> ~ 5.6 </Td> <Td> </Td> </Tr> <Tr> <Td> #000 Buck ("triple - aught") </Td> <Td> LG </Td> <Td> </Td> <Td>. 36" (9.1 mm) </Td> <Td> 6.2 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> MG </Td> <Td> </Td> <Td>. 346" (8.79 mm) </Td> <Td> 7 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> SG </Td> <Td> </Td> <Td>. 332" (8.44 mm) </Td> <Td> 8 </Td> <Td> </Td> </Tr> <Tr> <Td> #00 Buck ("double - aught") </Td> <Td> </Td> <Td> 00 - SG </Td> <Td>. 330" (8.38 mm) </Td> <Td> 8 </Td> <Td> </Td> </Tr> <Tr> <Td> #0 Buck ("single - aught") </Td> <Td> </Td> <Td> </Td> <Td>. 32" (8.1 mm) </Td> <Td> 9 </Td> <Td> </Td> </Tr> <Tr> <Td> #1 Buck </Td> <Td> </Td> <Td> </Td> <Td>. 30" (7.6 mm) </Td> <Td> 11 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> Special SG </Td> <Td> </Td> <Td>. 298" (7.57 mm) </Td> <Td> 11 </Td> <Td> </Td> </Tr> <Tr> <Td> #2 Buck </Td> <Td> </Td> <Td> SSG </Td> <Td>. 27" (6.9 mm) </Td> <Td> 14 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> SSG </Td> <Td> </Td> <Td>. 269" (6.83 mm) </Td> <Td> 15 </Td> <Td> </Td> </Tr> <Tr> <Td> #3 Buck </Td> <Td> </Td> <Td> </Td> <Td>. 25" (6.4 mm) </Td> <Td> 18 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> SSSG </Td> <Td> </Td> <Td>. 244" (6.3 mm) </Td> <Td> 20 </Td> <Td> </Td> </Tr> <Tr> <Td> #4 Buck </Td> <Td> </Td> <Td> </Td> <Td>. 240" (6.10 mm) </Td> <Td> 21 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> SSSSG </Td> <Td> </Td> <Td>. 227 (5.77 mm) </Td> <Td> 25 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 22" (5.59 mm) </Td> <Td> 27 </Td> <Td> 39 </Td> </Tr> <Tr> <Td> </Td> <Td> SSSSS or AAAA </Td> <Td> </Td> <Td>. 213 (5.41 mm) </Td> <Td> 30 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> AAA </Td> <Td> </Td> <Td>. 203" (5.16 mm) </Td> <Td> 35 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td>. 200" (5.08 mm) </Td> <Td> 36 </Td> <Td> 53 </Td> </Tr> </Table> <Tr> <Th> US Size </Th> <Th> UK Size </Th> <Th> AU Size </Th> <Th> Nominal diameter </Th> <Th_colspan="2"> Pellets / oz (28 g) </Th> </Tr>

What does 6 shot mean in shotgun shells