Haven't tried a .40, but have tried a 9mm Colt 635 and the muzzle flip from 9mm seemed worse than 5.56 out of a 14.5"+phantom pencil barrel so .40 should jack that up even more.

Unless you are shooting on a range that doesn't allow rifle ammo, I really do not see many perks with a 16" pistol round carbine.

"My message to my troops is if you see anybody carrying a gun on the streets of Milwaukee, we'll put them on the ground, take the gun away and then decide whether you have a right to carry it." - Milwaukee Police Chief Ed Flynn