Judging by the following code from MagazineWell.c, it seems like there is supposed to be inheritance with MagazineWell types:

// NATO
// Stanag - 5.56x45mm
class MagazineWellStanag556Class {}
MagazineWellStanag556Class MagazineWellStanag556Source;

class MagazineWellStanag556 : BaseMagazineWell
{
};

// Stanag - 5.56x45mm Small (for weapons which don't support large magazines like drum ones)
class MagazineWellStanag556SmallClass {}
MagazineWellStanag556SmallClass MagazineWellStanag556SmallSource;

class MagazineWellStanag556Small : MagazineWellStanag556
{
};

However, when testing this out myself, it does not work. There seems to be no way for two guns to share a limited set of magazines, like the comment in the code would lead me to believe. For example, gun 1 takes mags A & B, but gun 2 only takes mag B.

Not sure if this is a bug, or if it just hasn't actually been implemented. Would be nice to have some flexibility with magazine wells. As of now, I am forced to make duplicate mags that are only compatible with a single gun, rather than having them share compatibility.