The first pic looks like a French soldier (but isn't) with a Chauchat but then the others look like Serbs with their weapons, footwear and hats. The rifles look like Lebels.
When I see the separate Strelets sets (in the attack, on the march) for the ACW and Napoleonic Wars I wish that "tradition" could be extended to the 1st World War infantry. The "in attack" seems to be de rigeur for most 20th c sets.
These look better than anything else on the same subject.