cartriges for mgc/rmi Saa

Hello,

I've 4 Mgc SAA cot, some have the marks 'Sigle actoin army model 1874' and the other ones the marks 'cal 44-40'.

I'v only 6 cartridges (first model of MGC cartridges in one piece and a single cap in 7 mm) that goes in all models I've, and four guns to load.

Any idea of compatible cartridges I could use in these guns and possiblity with more modern cartridges who would accepts more than one caps ?

Best regards,