We know that in 1907, the Chinese started taking delivery of Mauser Oberndorf M1904/07 Rifles in 6,8mm calibre, and ammo to suit.
Ammunition of 6,8 was also made IN China from aboiut 1912-13, from samples seen in advanced collections.
In the meantime, Imperial China’s standard calibre was still the 7,9J cartridge for the various “Hanyang” Rifles.
So the question arises, in which calibre did General Liu make his 1914-15 prototype auto-rifles?(7,9mm or 6,8mm?).
The 6,8mm cartridge had been adopted for the NEW design Mauser rifle, and Rifles were delivered to China up till the beginning of WW I (August 1914)…remaining inventory in Germany was re-directed to several Wurttemburg regiments( Oberndorf’s Lande) and some rebarrelled to 7,9mm by Mauser, for general Issue.
IN 1916-17, the Republican Army decided that 7,9mm ammo was the way to go, and M1907 rifles commenced to be made in China in that calibre ( actually, sighted for the 7,9J cartridge at the time being made in China…supplies of 7,9S ammo was necessarily out of reach, as Germany was an Opponent…
It is assumed that existing 6,8 calibre rifles were bored out to 7,9mm and refurbed for issue in the beginnings of “The Warlord Period” 1917-1927.
After WW I ended, large quantities of 7,9mm calibre rifles were dumped on the World market, and eager merchants in China snapped them up for various Warlord factions squabbling amongst themselves and the central Kuomintang Government in Nanking (the “southern capital”). This cemented the position of 7,9 as the major Chinese calibre.
Other WW I surplus was also acquired, such as .303 (Ross Rifles), 8x50R Austrian (M95 Rifles), 7,62x54R (Mosin Nagants, out of Russia & Japan, and also Western Europe) and even 6,5 Italian ( over 80,000 M91 rifles in 1924-27 period, to a Warlord in Fujian province). And of course 6,5 Arisaka.
Chinese-made ammo of the 1920s for some of these calibres is Known and recorded ( 8x50R, 6,5mm Arisaka,) whilst others are rumoured but unsighted.
Liu did make another visit to the USA in the early 1920s, where his rifle was again placed in early tests for a US Auto rifle ( along with Garand’s primer actuated, Pederson’s Toggle lock, etc; these were the early “elimination” trials of 1923-25, before the real battle between Garand’s Turnbolt design (Gas trap) and Pedersons “T-1” rifle design both in cal. 276, came about.
Here again, the calibre of Liu’s offering was unknown, although an example is reputedly in the Springfield Armory collection. ( 6,8x57 or .276 Pedersen?
or even 7,9x57?).