Sir Charles is right. On page 130 of Packing Iron is the Mexican embroidered gun rig. The two buckles are for adjustment on either side of a large, oval or circular stamped/carved leather medallion. I have not noticed feature before in that photo. The leather medallion, with chapes on either side, with buckles attached, fasten to two billets on either side of the cartridge belt. The leather medallion, with billets on either side of it, fasten to two buckles on either end of the cartridge belt. Interesting!