Not that it means much.. But the only big, over 50 rounders I remember that were fairly common in the prehistoric pre an era, were AK drums and maybe the extremely expensive Beta C.
Bill Ruger said that no civilian needs a mag bigger than 10 rounds. So getting real AC556 Ruger mags was always difficult and way more expensive than it ever needed to be. I remember them being around the same price as Aug mags around the ban era.