This is a Japanese made 47mm, 1.85” Hotchkiss (47x131R) as used by the Japanese Navy in their 5cm Boat Gun. The brass cartridge case was made in Japan and has various Japanese markings on it. The pointed steel projectile has a standard Hotchkiss brass driving band design of the period and is threaded in the base for a base fuse. Later driving bands were narrower and were made of copper. No licence is required to possess this round in the UK if retained as part of a collection or display.