Looks like somebody was so thrilled at the idea of designing a bullpup weapon that they forgot that you still need to put a firing mechanism in it. This thing isn’t compact, it’s tiny! If you think about it as a P90, you’d barely have space to put your magazine above the barrel, and I’d discard the idea of putting it in the stock as it doesn’t really have one worth mentioning.
Number 2 “machinegun” also looks rifle sized by the way.
Last (minor) point about the stun batons, I’m not overly fan of the sweeping guard that’s only really useful if you engage in serious melee against a similarly armed opponent. Number 5 (with finger slots) is my least favorite as this could lead to its fair share of broken fingers!