The factory even used to supply a dry fire practice target with their guns.

Here is what their current website says about it-

Can I dry fire my S&W handgun?
Q: Can I dry fire my Smith & Wesson?

A: Yes, except for the .22 caliber pistols which includes models 22A, 22S, 422, 2206, 2214, 2213 and 41.

.22 caliber revolvers such as models 17, 43, 63, 317 and 617 also should not be dry fired.

Q: Why can't I dry fire my .22 pistol or revolver?

A: Dry firing a S&W .22 pistol or revolver will cause damage to the firing pin.