That's not an M16
It looks like a modified shotgun, and you won't be able to get away from the gun-look if you need a long tube and a handle. "Shotgun mics" are called that for a reason. :)

That's not an M16
it's indeed anything but an M16.
The scope looks like a cheap model typically sold with air rifles for target shooting at short distances.
The barrel looks like it's got a cylindrical cover around it, highly unusual and impractical for use in a weapon.
Stock looks exceedingly flimsy for a large bore shotgun.

Looks to me like someone slapped together some pieces of PVC tubing and added a few parts from an old sports rifle to make it look "kewl".

I've lived with M-16's . . .
. . . and that doesn't even look like a toy M-16. I could see how the author could use the "it looks kind of like a rifle and an M-16 is a rifle" argument that big media uses.