Are (US) military drill instructors particularly skilled in unarmed combat?

[Marvin_the_Martian]

@Zakalwe

I was flight deck crew on an aircraft carrier, if we need handguns, we’re fucked already.

Maybe one of these would be more useful in that case:

Would an updated boarding ax/gun work properly?

So in the midst of looking up weird weapons for a story I may or may not write, I came across information about this combination boarding ax/rifle. It’s apparently workable (though you obviously couldn’t run around with it ready to fire whilst fighting). My question is, could you remake it with a more modern shotgun/rifle inside the handle? Or would something like the kick make it unwieldy? I don’t know anything about guns.