Polymer, indistructable, flawless reliabil
Was totally serious. Unaware of issues with something as seemingly ubiquitous as a mag for a rifle or pistol. My "disposability" question remains. I expect the VN landscape is littered with literally hundreds of thousands of empty M-14/16 mags, maybe now being turned into belt buckles. Do/can you shitcan an empty mag on the battlefield these days, or do you have to recycle/account for them? That's a serious question as well. I don't expect these new things are stamped out by the thousands at a penny apiece.
There was a time when M-16 aluminum magazines were packaged pre-charged and in cloth bandoliers. Currently, magazines are no longer disposable items - individuals are equipped with "dump pouches" to carry empty mags. GI aluminum mags are quite durable - and some NATO countries use steel mags - all intended for reuse.
Feed lip damage seems to be the limiting factor whether a magazine gets diposed of or not. Armorers replace followers and springs with ease.
The Magpul PMAG is a result of focused product improvement - it is a wonderment of assembly and durability. I believe GI aluminum mags are procured for around $8 each, PMAGS for slightly more.
10, 20, 30, 40 and 60 round capacity models are all available and are rock solid in reliability.