Yes, I concur, few and far between with the French. I imagine the different ammo required on top of the other types, was a logistical step too far.
As CM says, dating photos is difficult, as the U.S. was supplying weapons to South Vietnam before the French actually officially left and even as late as the Early '60s, you will find occasional SVN regulars with French or Japanese helmets and MAT 49 SMGs, mixed in with the mass of U.S. equipped guys, let alone the civil guards and others still using older weapons. Certainly for much of the Early '60s the Viet Cong in the far South was far more uniformly equipped with U.S. weapons than the South Vietnamese Forces themselves; albeit that the same weapons had originally been issued to ARVN in the first place.