The Boston PD apparently had some.

Seems the majority of them went to the Post Office and were later destroyed. A fairly small number was sold on the commercial market, and there wasn't much of an effort by S&W (if any) made to promote and sell them, but I could only guess why not.

The only one I have seen is the one I own.

For those who may not know what a Model 45 is, it's simply a .22 M&P. Or maybe a K22 without target sights.