How could one distinguish between the copper-nickel clad copper and .400 silver Half Dollar coins 1976S ?
Mine looks silver in color, does not have copper showing on rim.
Should there be any differences in weight and diameter?

You already mentioned the copperring at the edge, that can be used to distinguish them.

The diameters should be exactly the same

There is a weight difference, but it's small:
11.50 gram for the silver clad
11.34 gram for the copper-nickel clad


They sound different if you "drop" them on e.g. a table. Silver has a much nicer ring.

Thanks for the information. It might be difficult to distigwish this slight weight difference. My balance allows for 0,1 gram error.
I noticed that Krause SCWC lists the copper-nickel clad 1976S Half as issued only in Proof. If this is the case, then mine is silver, since it is not Proof.

You can get rolls of the 76-P/D at the bank even today around here, but the S, was proof only I thought...silver and clad.

'76S Clad were proof only. The Silver was both Unc. and proof.

Thanks for your answers. Now I'm sure that the 1976S UNC Half Dollar I was asking about is silver.
Next comes the interesting part: Krause SCWC says that it should weight 11.5 g, the same as e.g. 1968S Half Dollar. My balance says that my UNC 1968S Half weights 11.5 g as in the book, but four silver UNC 1976S Halves (KM#205a) in my posession weight 11.4 g, 11.5 g, 11.6 g and 11.9 g
I would say right away that all four coins are struck and have nice "silver" sound. They don't look fake to me and I'm not new to numismatics. I also don't expect such a common and cheap coin to be counterfeighted. My request to those who has 1976S silver Half Dollars is to weight their coins and see if they can confirm such a significant weight fluctuation. Do you know of any restrike of this coin?

Andrey