ACE3/addons/compat_rhs_gref3/CfgMagazines.hpp

class CfgMagazines {
    class CA_Magazine;
    class rhsgref_50Rnd_792x57_SmE_drum: CA_Magazine { // drum, but still just a belt
        ACE_isBelt = 1;
    };
    class rhsgref_296Rnd_792x57_SmE_belt: CA_Magazine {
        ACE_isBelt = 1;
    };
};