How do you know it wasn't German supplied or left by the Germans in 1918, (Germany supplied arms and soldiers to the Whites in Finland), the marking on top of the barrel? French were big cheaters on the terms that ended the war and the stated causes and intent of England and US.... France was suppose to restrict arms proliferation after the war though Poland was a case study in how serious France took any such silliness.
WW- is highest block known, three examples known up to the 6500 ww range; so this is VERY late production and easily could have stayed in Finland when the Germans left, not sure when they departed but Jager were involved.