We (ST2) were given Steyer AUGs to shoot about 1981 by the reps, and took them to the ranges at A.P. Hill. (If anybody shot a Steyr AUG before 1982, please tell me!) Anyway, at that time the factory tech reps told us that the gun was meant to be fired by conscripts with minimal training. That's why the 1.5 optical scope with the circle reticle. ("If a man fits like this" etc) Anyway, at that time the rep said they were planning to use throw away magazines, loaded at the factory. They were honey-colored translucent plastic even way back then, but not throw away. I don't know if anybody is issuing throwaway preloaded mags yet, but it makes sense to me.
I would like to see the magazine concept approached in a different way. The FP-90 mags are possible by top loading, and ammo carried sideways as in the 5n7 rounds they use. A bull pup design with the ammo mag on top acting as a cheek weld versus the mag in the bottom might also be looked at.
Bull pups have their place IMHO. They deserve a better arraingment/design but the concept is valid I believe.
Stay Safe !