I have been coin roll hunting for a few months now. Last night as I opened a roll I saw a really white edge on a coin similar to a 90% half. No trace of copper in the edge. Has anyone ever seen a 40 or 90% D mint 1976 half dollar.
As I said in PM to UNC, planchets rejected by San Fran would be shipped to Denver to strike circulation issue halves. On rare occasions, someone would accidentally toss a silver (40% in '75-'76) planchet in there and it would find its way to Denver and into circulation from there. The odds of this being the case are extremely slim, and I'd lean towards a plated coin.
Weight may not tell you much. The tolerance range for half dollars is wide enough that there is a significant overlap in weights between the coppernickel clad and the 40% silver halves. If it is questionable and the weight says that there is a chance then the only true test is specific gravity.
