'J.L.', 'J.F.', and 'J.F & C.' were marks used by Joseph Janssen, Janssen Frères & Janssen Fils & Cie
http://www.littlegun.be/arme%20belge/artisans%20identifies%20i%20j%20k/a%20janssen%20gb.htm

This Crown over JF is thought to be Jean Falla