question on FAL magazine

[Tom in N.J.]

RCS.. I have metric FN FAL mag that looks just like your blue one on the left in the first photo. My mag has a mark on the rear consisting of an oblong with a mark inside. My old eyes are unable to make it out. Metric mags have the small stamped out protrusion to engage the receiver on the front, inch mags have a wider heavy lip to retain the front of the mag. At least seven countries made FN-FAL mags.