In the card showing pigs, "FM" in the stamp area stands for "Franchise Militaire" which usually is an overprint on the stamp. Maybe SP77 was in a colony which had run out of stamps.
The card A.C.F 4 has "Abeille - Cartes - Paris on the address side, most likely as a publisher rather than a printer. I don't know whether A.C. F is one of their marques or just refers to a series.