Chinese made Type38 75mm field gun case

This is a casing of Chinese made Type 38 field gun (75x294R).
I found this in Japan, but it seems to be rare in China.

It weighs 1239 grams and was manufactured in December 1924.

The headstamp has “民 13.12” and the symbol for "東 (East) " in graphic form.
The “民” stands for Republic of China calendar, which means it was made in 1924, the 13th year of the Republic of China.
The symbol for “東 (East)” means that it was manufactured at the Three Northeast Provinces Arsenal(東三省兵工廠) or Mukden Arsenal(奉天兵工廠).