WIP: Double Bullpup concept

This is a concept of a Double bullpup style weapon that combines a DMR, SMG and has an optional underbarrel mount that could be a shotgun or grenade launcher.  The top one has an integrated shotgun that has a Kel Tec KSG style magazine system that can hold either two different types of shotgun munitions or alot of the same kind for double the amount one would normally have with an ammo tube of that size.  like the respective shotgun its styled after it can either fire either tube with a switch near the trigger or set with the same switch to alternated between both chambers (I may be thinking of the UTS-15 by UTAS.  I may style it after that since it would make a little more mechanical sense.  To those who don't know the UTS-15 has a similarly functioning dual magazine tube shotgun but the ammo tubes are over the barrel.  I might also not be using the correct terminology, so I apologize to those that are sticklers for that sort of thing).

The one on the bottom was what I initially drew but has under-mounted rail that allows for more things to mount under it or leave it bare to lighten the weight for those not wanting the encumbrance of weapon part they may not have the need of.  its depicted with a bullpup revolver shotgun styled after the Crye Precision SIX12 in its under-barrel form.  So its a bullpup attached to a double bullpup, which could be called a bullpup with in a bullpup; its Bullpup-ception