the 360 BPE 2 1/4" is the original, coming from GB between 1865 and 1870, imho, the first CF cartridge with a caliber under 10 mm.

like the other early BPE cartridges it was used in germany but had a lot of competition with many cartridges using this for basic brass. the 9,3x73R was maybe developt before nitro powder was available but once loaded with nitro it made a good cartridge with low pressure what was top for the older break actions around 1900. then it became realy popular into the 1920s.