I enjoy your little games, mine wasn't a guess either, I thought pretty long and hard and something about the "pinkish" color and ratio of copper to nickel on the edge seemed to be different. I might have missed that silver personally also, but my ears are trained to hear silver. I can't tell you how many countless times I've missed a silver dime and caught it sound checking after I glanced over the roll. out of 1000 boxes maybe I missed 25 and picked them up that way. of course there is no way of telling how many I might have missed. LOL
and of course, no silver half dollar is getting by me :P
Have a good one!
Buff