Is it an FM-FSL (FM- Fabrique Militar)?
Argentine variation (F.M.A.P./Fabrique Militar Argentina Producion? receiver) of the FN FAL 50.00 and 50.64 (imported by Springfield Armory- green box?).
If pre-89, good finish and quality and about $1000.00-$1500.00 less than a comparable FN FAL.
Hope this helps.
thanks on the info tony. im pretty sure it is not an all original fn rifle, since all i can find on it is that the argentine semi auto service rifle is the only one with any markings with fsl. thanks a bunch!