British usage
In 1914 approximately 150,000
Arisaka Type 30 and Type 38 rifles and carbines were sold to
British forces (mainly to the
Royal Navy), where they were used for training. The 6.5×50mm round was subsequently produced in Britain by the
Kynoch company and was officially adopted for British service as the .256-inch (6.5 mm) caliber Mk II in 1917. The
Arab armies organized by British Captain
T. E. Lawrence to fight against the
Ottoman Empire during
World War I were armed with a portion of the 500,000 rifles purchased from Japan from 1914 to 1916, and many were the obsoleted Type 30 rifles which had seen heavy service during the Russo-Japanese War in 1904-1905.
[2][3] In all, the 6.5×50 mm Japanese semi-rimmed round has been used in either Japanese or domestically designed weapons by
Japan,
Russia, the
United Kingdom,
China,
North Korea,
South Korea,
Thailand,
Finland and
Indonesia. Many of the British Naval Arisakas were given to the
White Russians.
6.5 mm Arisaka rifles were used mainly by the British for training, homeland defense, and by naval units. In 1916, the rifles were shipped to Russia and none were left by the end of World War I.
https://en.wikipedia.org/wiki/6.5×50mmSR_Arisaka#British_usage