During the interwars period, the need for automatic weapons in China was massive, and many factories were looking for designs to copy or build. The Tsing Tao hand held MG was one such copy, of the Bergmann submachine gun. It was identical to the original, safe for the magazine being placed directly under the receiver instead of on the side.
It was functionally the same gun, and used a variety of magazines, here it is portrayed with the 50 rounds "standard" .30 mauser one.
The Tsing Tao SMGs were produced in large quantities, and saw use in the Civil War and in WW2.