The reason I posted that particular gun on the other forum was that I was trying to find out why this would have happened and if it had happened to others.

I wasn't looking to start a thread that got sidetracked into safe loading habits and whatnot. I simply wanted to see if this has happened to others before.

I looked at the actual gun last week and the owner said it was alright for me to post a thread about it.

The rounds in question were reloads. He drops his own 250 Keith's and puts 'em in front of 16.5gr of 2400. Yeah, they're hot and he knows they're hot. Apparently hot enough to bell the forcing cone.

In any case he's sending the gun to S&W and will see what they say.