Saw some of the same thing happening, I was told nothing else was rig proper for this weapon.
Best I can figure is the dummy is not in a good place for all uses, and the difference might be the shader properties. there is a skinned bone weapons shader, and also a non bone driven shader for Melee weapons.
So that might be something to do with it.
Also in the start marker after you attached the third view character, is the offset for the dot in the properties settings.
Maybe when Errant AI, gets online he can shed some light into the weapons shader a bit on this. I will point this thread at him in PM so he knows.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit