Vintage ACH Helmet, Military or Law Enforcement Issue

Looks like this was an all green helmet and someone added the tan but not sure. Open face helmet c1980s. Good condition with new looking straps. 

I am not a helmet expert so info provided is based on my best research. Please look at all photos and make your own determinations. 

In good shape with a good amount of scratches and chips but no cracks. 

11" long 9.5" wide and about 7" tall