It looks pretty convincing. You did a great job on the digital camo. One small thing that I would point out is the sling looks like it is wrong. It looks like a cross between a 3 point sling and the standard 2 point sling. Also if the Marine was holding the weapon like that, they definitely wouldnt have the sling just hanging loose. If you were to take it and slide the back of the sling behind his rear arm then it could look like the "Hastey" sling we use in the field. Also if you wanted to add some weathering or other small details. You could put a rifle number on the right hand side of the buttstock of the M16. The placement would make it to where you could read the number when the rifle is barrel facing straight up in the air. That is how they are stored in the Armory. You could pick any number you wanted from probably 1 to 400. My rifle number is 114. BTW the numbers are in white.
Again I dont know if you are wanting to weather the weapon at all or not but if you did... The plastic buttstocks fade after time to be more greyish colored. The stencils that the numbers are painted on with often times are placed crooked and there is overspay sometimes. The black on the rifles also wears down fairly quickly. The flash suppressor at the end is worn to a metal color quickly. Also the ejection port cover. There is a little square on it that the corners get worn down on to metal colored. The bayonet holder at the bottom get worn fast too.
The magazines are almost never black either. They are more of a gunmetal grey color that quickly wears down to an almost brass color underneath in spots like the corners and where the magazine is inserted into the rifle.
I don't know if any of this info helps at all. Again I don't want to sound like I am critisizing your build at all because it looks fantastic. I am merely trying to assist you with some small details that you might be unaware of. It looks great as is and you might not want to muck up such a great paint job. But I thought my insights couldn't hurt at all.
Thanks
Ben