I've had first hand experience with a 'ka-boom' some eight years ago. It wasn't a double load - in fact, it was a relatively mild load for a .44 Magnum, the 300gr LSWC over 6.1gr Titegroup having been chrono-ed at 810 fps. The cause of the destruction was me - I had shot 200 .44 Specials & Russians that day - and grabbed the last box in my bag - those 300gr .44 Magnums. Hard to insert - and knowing better - I rammed them in. The first three were fine - even hitting a steel plate at 110yd handheld. The next round destroyed the gun, making a muffled 'boomff... tinkle tinkle' as small pieces bounced off the tin roof. The next live round was distorted. I never found the primer or the front sight screw. I called S&W concerned about the metallurgy of the cylinder - the first question from them was did I ever shoot reloads. I admitted that, if they had tested my 629MG with commercial ammo, that was it's only such experience. In fact, I had never loaded a 'real' .44 (or .357 or .327) Magnum - and still haven't.
I sent pictures and description to Hodgdon's. They agreed with S&W. It wasn't a stuck round. It wasn't a double charge (Actually, because of the deeply seated bullet, 9.6 gr starts compressing the powder to load - 10 gr won't fit. Hodgdon's said 10.5gr would be safe!). It was my stupidity... I certainly knew better... I had become complacent - careless. The lead and carbon residue from shooting the short-cased Specials and Russians piled up under the Magnum's crimp, at the very least, slowing the crimp release - perhaps not allowing the release. The resulting pressure spike burst the chamber. Hodgdon's said it would certainly 'grenade' at less than 6 gr of Titegroup in a 'stuck' round.
S&W agreed it was my fault - my carelessness - and not the ammo, or the revolver. They then apologized that they had no 629MG's - but would have me a regular production 4" 629 overnighted to my LGS by Friday, if it would pass the QC & live fire test after dropping off the production line. They just wanted me to pay their cost... ~$271 shipped! My LGS didn't even charge me a transfer fee! Ruger may shock you with a similar offer!
To Savageman25.... did you, by chance, shoot a bunch of lead .38 Specials before shooting the .357 Magnums?
I felt blessed that day - I had a scratch on my supporting left arm and a scratch on my left eye safety glass lens - and you bet I'll always wear eye protection. I am thankful that Savageman25 wasn't hurt.
Stainz
PS I still dissected 300 of those 300gr LSWC rounds - all loads were between 6.0 & 6.1 gr! Of course, with a Dillon 550B press, loading a partial load is extremely difficult.