Becoming a target yourself
Why expose yourself?
Great thinking! We can just arm our soldiers with concealed pistols!
Why expose yourself?
Well, first, that's their job. And second, because they're exposed anyway.
Rifles are offensive weapons. Pistols are defensive weapons.
Only someone who knows absolutely nothing about firearms suggests taking on a rifle with a pistol. That's the equivalent of "shoot the gun out of their hand" fantasies.