The stock looks very separable from the actual weapon, and therefore if the user were to adapt it for his/her ergonomic benefit and remove the stock, than they'd have no projectiles!
Especially on a double barrel weapon, there's got to be some mechanism to designate and chamber the rounds efficiently, automatically (being enclosed), and on a small scale judging by the structural implications.
So, yeah! Just my take on it. I'm studying electrical/mechanical engineering.