This is from Qui est Qui "Who is Who", a recent publication.
For CAP


This is a 1909 List of trade marks

CAP

Neumann Freres


So, the gun should not be older than 1900.  Each of these of old guns can be a like puzzle.  Some times you can be very sure, other times, well you may get close....
The lack of marks on the receiver was not surprising, a little disappointing.
There is a smokeless proof on the barrels.  If after 1903 it is a nitro proof.  I do not have the proof pressures for rifles during this period.  Perhaps some one else can help in that regard.
Pete