Well the majority just sees it as another M16; an M16 we have over 10 different models of.
the NV service rifle if anything is modeled after a 1970's AR-15, not an M16
That. Also, I see nothing wrong with making something like this from scratch. I had 2 people via PM and The Corporation offer to help and a friend from school is making a Fallout 9mm Pistol, Combat knife, and frag grenade to go along with this.
Sure there are add-ons out there that could be substituted for them but re-skinning is sometimes worse off than building something from scratch. It's almost like a house of cards: It takes time to make but if you want to go rearrange the middle of it, that could prove difficult.
EDIT: Highlighted some differences on OP