Don't remember seeing one for M4 - although I think Sanctum Arts did one but that was long ago and is no longer available.

Only Hazmats I can think of are

the Hazardous Materials Clothing Set at content paradise for the generation 2 poser figures - http://www.contentparadise.com/productdetails.aspx?id=89

the LoREZ 14 MU Worker which is a stand alone figure at daz - http://www.daz3d.com/lorez-14-mu-worker

or for a more sci-fi hazard look the HYPER SUIT or A.T.A.C. Suit both for M4 by Xurge -

(LInk removed for TOS violation) Please do google search for Xurge3d and sorry for the inconvenience.