Well done Raimey.
Here it is in ah-mer-kan wink
http://www.littlegun.be/arme%20belge/artisans%20identifies%20m/a%20magi%20sprl%20gb.htm

S.P.R.L. is likely something like Syndicat Pour (la Fabrication?) Liégeois

As Mike discerned, and with Bro. Bob's help, the gun is c. 1900 (maybe with help from Dumoulin Lambert) then re-barreled by MAGI and proved in 1963.

Neat how we're smarter together, which should be the point of this Forum.