It is the smallest cartridge in that pic. Do an image search on ‘rifle cartridges’ and you will find a lot of pics with the cartridges marked. Many with a lot more calibers in the pics.
38 posted on 02/22/2018 8:59:02 PM PST by TigersEye
(13 Russian Facebook trolls ... and a Siberian partridge in a Russian Olive tree.)