Physique Trouble on MC Model

[Jerrari]

I Made a biped and started to edit the physique on the head. The head looks normal in its standard position but when i rotate it it has a lot of distortion below the visor. Is there a way to lower the amount of distortion on the metal areas of the helm?

[ledhedgn]

its not that there is lots of distortion there, its just theres less, you can use weighted verticies to get what the envelopes dont get