I found this coin roll hunting. My first thought upon seeing it in the roll was "all right, got a silver". There are absolutely no visible signs of copper in the rim. It is a 1971 D. It weighs more than a clad half (11.36 grams) but not as much as a 40% silver half. I took it to my LCS and the main coin guy couldn't figure it out. I read online there were some 1971's made on 1970 planchets but the weight has me confused.
I just went thru about $300 in halves. 71D's have quite a few minor DDO's. The Pickup is in the I of IGWT. Anyways these were saved nearly as much as the 64 thru 70 but never caught on as a valuable variety. I would weigh the coin if you have any concerns. I think I see a copper core on your third side photo.
Here's a better pic. There is zero copper showing. Several people at the coin shop looked at it and no one saw any copper.
Interesting I will wait for more opinions. Try calibrating your scale. 40% weighs 11.5 Clad weighs 11.3
Maybe a clad that was nickel plated? It's a 71D so there shouldn't be any 40% silver ones, BUT You could scratch a few reeds and see if copper shows through? 1971-D Half Struck on a 40% Silver Planchet 1971-D 50C Half Dollar--Struck on 40% Silver Planchet--AU55 PCGS. Kennedy Half Dollars were 40% silver between 1965 and 1970, including the 1970-D which was struck only for mint sets. An unstruck planchet from that production was somehow mixed in with the usual copper-nickel clad planchets during the subsequent year. The peripheries of this example are softly struck, as are the centers of the devices, and there are a few faint handling marks from brief circulation. Lightly toned and with ample remaining luster. Maybe someone rolled the reeded edge in mercury. That would coat the copper on the edge.
