Colored tips would be revealing. They seem not to be black (armor-piercing), certainly not red or orange (tracer). Frank
I collected them from the desert shooting range Ft Bliss when I was 8 and my father was on special assignment at the missile range. WW 2 50 cal machine gun practice bullets. I once had a 5 gal bucket of them. I was with the Commander's kids and all the armed guards that drove the perimeter in jeeps looked out for us. They called us the little desert rats.