I too have been shooting guns since that age, and I too was trained by the US Army, I too earned my marksmanship badges on the M-16 ( and M-60, M2 and even the M10, as I was in ARMOR)
I too took that same oath.
Currently, I am a Range Safety Officer, Rifle, Pistol and Shotgun Instructor.
But I have no problem with having semi-automatic firearms in the hands of the American Public. That was one of the rights that I promised to defend when I took that Oath.
And because of that training, I know that an AR-15 and it’s clones are not a weapons of war, the M-16 and M-4 are. As you well know, no Infantryman would carry an AR into battle, they would carry an M4 instead. The AR and M4 are markedly different firearms with very important differences in capabilities.