I still can't find any reference in the Firearms Act, the Criminal Code or any of the Special Bulletins that indicates that these mags need to be in 10 round bodies only. Again, they are not modified. They are factory mags made for the LAR-15. Also, they are not "dual caliber". They are designed to hold 10 rounds of 5.56x45 ammo only.
The reference to "GI style 10rd body" is questionable as well. To my knowledge the US Government has never issued a 10 round M16 magazine so if we are using the GI standard they would need to either 20 or 30 round bodies.