Interesting - the Lion over PV is a Belgian commercial nitro proof, used after 1924, but the SN you give is not among known commercial SN's, which are 20000 to 215000; and suffixed SN's 1 to 100000 with suffix "a", "b", or "c".
AFAIK, military guns had a couple of military acceptance stamps, like "WaA613", "WaA103", & "WaA140", and 5-digit SN's, some with letter suffix.
There were also some high-polish WaA613's in the 288000-289000 SN range - higher than the SN you gave.
What is the finish on your M1922, high-polish, military, or rough military ?
Is the mag phosphated ? (The mag might have clearer stamps, if it's original to the gun.)
What kinda grip panels ?