The weird SMG from Ground Zeroes/TPP, the Sz.-336, it's DEFINITELY a PM-84 Glauberyt. Don't believe me? Look up an image of both the Sz.-336 and then in another tab the PM-84 Glauberyt; they're strikingly similar and share the same caliber. Also, it was in service in 1984, the year Phantom Pain takes place in. If you argue, how can XOF have it? Remember, in Peacewalker, the chronological game that takes place in 1974, before Ground Zeroes, you can have MSF develop a HK CAWS, a HK G11, a FIM-92 (stinger), and various other weapons ahead of schedule. And XOF is a unit of Cipher, so they should be as technologically advanced as MSF, if not a bit more thanks to their near endless amount of 'funding'.