Well, something better than "Take a two round plastic container as you move past the pallet"
Mystery Ranch had a 84mm round carrier for their packs- perhaps a skinny 2-3 round version for 60mm?
Single/double round MOLLE pouch a'la 40x46mm rounds?
Specialised RAID style bag with configurable internals (maint kit/optics/CES/limited rounds for gunner & plain rounds for the mules?)
Metal/synthetic 'ready' box for vehicles or positions? Take an existing box/can & configure as required with padding & liners.
Specialised carry bag based on the 7.62x51mm link bags available but with dividers for individual rounds & additional padding? Those sound like you put together your self configured to your own purposes.