My post was just random thoughts, sorry that it made little sense.
in short: Stg44 amunition comes to my knowledge in 240 round battle packs (8 x magazine of 30 rounds) In those battle packs, depending on who made them, where boxes of 14, 15 or 20 bullets. Sometimes on stripper clips, sometimes not.
now, the question was, why was it done in these weird number (to me)
Remember, you only loaded 28 rounds to keep from harming the spring.
Then you must cary 16 loose rounds in your pocket, well, 36, with 1 magazine in the weapon, 6 in the pouches.
You would assume some thinking went into the chosen quantities for the boxes.