Wow. That is a little scary. I was a young E-3 back in the '80s when my Army unit got the then-new A2s. Almost exactly twenty years later (about five years ago) I had an argument with an Army civilian logistician about the weapons in the field and he insisted adamantly that there were no more A2s in theater (which I disproved that day with photographic proof). But an A1? We don't even buy the correct ammo for those anymore I don't think. They take the old--yes Vietnam era--M193 Ball. The 80s-era M855 has a higher chamber pressure, supposedly not safe for the A1s hence the green paint on the tip to distinguish, and require the A2's tighter rifling to get it's higher mass to be stable. The very latest M855A1 has more of both chamber pressure and mass. You REALLY shouldn't have an M16A1 on today's battlefield.I'm really not kidding....they issued me an A1...
I feel for you bro. Please stay safe