6.5x50mm is pronounced ''six point five by fifty millimeters''. SR stands for ''Semi-Rimmed''. Arisaka ('''有坂''') is a Japanese surname, and is pronounced ''Ah-REE-sah-kah''. In real life, the cartridge was named after one of its original designers, Nariakira Arisaka. In the Mazes, ''Arisaka'' is a typical youkai surname as well, and it is often believed that a youkai individual also named Arisaka has invented or introduced the cartridge to the Mazes, though it has not been proven one way or another.
This caliber may also be known as '''6.5x50mm''', '''6.5mm Arisaka''', colloquially '''6.5 Ari'''. There are also '''6.5mm Japanese''' or '''6.5 Jap''' (as this cartridge is of Japanese origin in real life), although those last two designations are not used in the Mazes and are only provided here for reference.
= Compatibility =