If it is built from an L1A1 then it is an inch FAL, so therefore it could even be Pakistani or Indian L1A1 kits. I am thinking it is not Australian or British. If it is an inch kit then it should use inch mags, but since it uses metric mags the receiver was probably modified to take metric mags. My guess the reason for this is there are a lot of inch kits out there so they built the Receiver to work with L1A1 inch kits, but yet still be compatible with metric mags because metric mags out number inch mags like 100-1.
American Barrels in general are not as nice as the barrels from say Steyr or Imbel. Steyr barrels are considered tops, very accurate and chrome lined. American FAL barrels are usually not chrome lined.
By law since 1989, the Receivers (which is considered he gun) of semi auto guns have to be made in the USA. American FAL receivers are either Century, Hesse, Enterprise or DSA. DSA is considered to be tops. Enterprises are considered almost garbage, and Century and Hesse are considered complete garbage.