I shoot BB's occasionally out of my S&W 629. They will not blow up your gun. The smith is not as strong as the Ruger so it will wear out much faster if heavy loads are used but a few every once in a while is no big deal. They would not sell them if they would cause a catastrophic failure. I have killed whitetail w/ the BB and it works just fine. Yea, I know, overkill for deer.
"Suppose you were an idiot, and suppose you were a member of Congress, but I repeat myself." Mark Twain