WOW! We're just glad you weren't injured. It will be interesting to see what S&W has to say and I'll bet they'll want to look at your revolver. The vast majority of kabooms like this are caused by overpressure loads. A friend of mine did the same thing to a beautiful Colt Python. He sent it back to Colt and they concluded that the powder charge in his reload detonated instead of burned, and ofcourse since he was shooting reloads it voided any warranty. Let us know how things turn out.