I don't think that's the case. Maneuverability matters in close quarters, and a spear doesn't work if the adversary is too close. If the adversary is far enou

I don't think that's the case. Maneuverability matters in close quarters, and a spear doesn't work if the adversary is too close. If the adversary is far enough for a rifle-length spear to work, shooting them with the rifle also works. Closer than that and you're better off with the knife or your bare hands. (Also, you might be better off using the rifle as a club.)