AR-15 Headshot!!! One Round!

So, This was on the April Fools Range Trip. On that day we did some shooting with the Yugo SKS, and two loaner Guns. A Savage Model 10 in .308 Winchester, and a Custom AR-15 (DPMS Upper, Plum Crazy Lower). Both Rifles are hunting/Plinking rifles and that day was really just to get a feel for them, sight them in for Range days to come. Well On that Particular day I Forgot to buy some .223 for the AR and did not realize that Until we were out at the range. So I did some scrounging around and looked to see if I could find some rangetrash or soft primer hit rounds that may be sitting out. I happened to find one that was ejected on a double feed drill that was left behind so I Loaded it up in the AR and decided to see If I could score a headshot on my first try.....