I dry fire my semi-autos and my J frames a lot...without snap caps. The only thing I don't dry fire is my .22 rim fires.
Opinions will vary, but according to the S&W FAQ on their website:
FAQs - Smith & Wesson
"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."