M-14 (and M1) bandoliers have six pockets each, and will hold 2x5-rd stripper clips/pocket.  Be sure to get the cardboard "silencers", and slip a mag loading "spoon" into the same pocket in each bandolier. IIRC, you can store 4 loaded bandoliers in a .30 cal. ammo can, with a little room left over for some silica dessicant and a couple of loose stripper clips of ammo.
Don't know of any issued mag bandoliers.
Typical combat ammo load for a GI M-14 rifleman would have been 2 M-1956 O.D. cotton canvas pouches with 2 mags each, 1 mag in rifle, and a couple of bandoliers.  Lots of guys carried more.
Marines, at least for a while had a unique pistol belt with female snaps every few inches.  To these were snapped the single M-14 mag pouches seen every now and then.  At some point, they also switched to M-1956 web gear, although the changeover may well have coincided with the switch to the M-16.
HTH.