The Coinalyzer comes preset to pass copper pennies and reject all else. It can be reconfigured for halves. I just tuned and tested mine to see how well. With halves having 3 composition states to compare, discrimination must be set to high and VR tuning is critical.
Tuning for 90%er pass with a 90%er as a sample will result in all clads and 40%ers being rejected.
Tuning for 40%er pass with a 40%er as a sample will reject 90%ers but many clads will pass along with the 40%ers.
The option that seems to work best is to tune for clads pass with a clad as a sample. The result is clads pass and 90%ers reject. 40%ers will reject most of the time but tuning is ultra-critical to get it even that good. A tiny fraction of a turn on the VR tuning will make or break proper operation.
I really wouldn't trust the discriminator in the Coinalyzer to be reliable enough for 40%ers, as hard as all silvers are to find these days. You can buy a suitable CMI CC-16 off of FeePay for less than the Coinalyzer. Only it's not going to be plug & play, it'll require making up a wiring harness using a power supply. A little wal-wart cube can be used.
Bob