First off. The problem with the spas 12 was that it was a little too close to the reality of a shotgun and broke pretty much every other weapon in the game. The problems with the design of these guns is that they take so many cues from real guns, like detachable box magazines, red dot sights, exposed hammers so on and so forth. If they had just designed the guns to be futuristic, then these things wouldn't be necessary because they could put any interesting scifi mechanic they wanted into the guns. Instead they just made guns that were modern and some that were older, and made them operate basically the same, while making them simultaneously completely illogical.