This magazine features FN's signature translucent smoke finish. This is the 50 round mag. The pin is on the top, not in the circle you mention; that was the older mags.What color are these?
Where is the pin inserted?
The picture looks like a "smoke" 30 rounder, just trying to figure out if these might be "amber" 50 rounders with the pin in the little circle by 5.7x28 stamp.