SnidelyWhiplash and Protocol Design,
Agree with your most recent posts.
I think a suitably inspired reloader can come up with rounds that will grenade any firearm. At that point I don't think forged vs cast counts for much.
For my CCW classes, to emphasize my point of using the correct ammunition, I collected photographs of grenaded revolvers. I think all brands and models were well represented.
I also agree on the shrapnel going sideways. In looking at photographs of blown revolvers, the failure is (obviously) with the chambered round. The damage to the top strap appears to me that the top strap, prior to failure, was enough of a barrier just long enough to direct the grenade forces from upwards to sideways, as that is the path of least resistance.
I have no experience in this area. Given my line of work, I either fired duty rounds, the Treasury Dept 38+p, and then the equivalent in .40 cal once we went to semi-autos, or wadcutters for competition. I had no interest of firing higher horsepower rounds for recreation.
Once we went to the issue Model 66s, we were required to carry those, not personally owned revolvers. But our manual had an interesting semi-loophole. We could carry a back up firearm, regardless of caliber, provided we could qualify with it. I had a very close friend who carried a 3" 625. He asserted, with great enthusiasm, that the .44 spl loads were far superior to the "sissy" Treasury .38+p loads we were issued and had to carry in our issue duty revolvers. I would respond that if he truly felt that way, then he should shoot himself in the foot with the duty load and tell me it did not hurt. That its how these discussions always ended.
I have frequently related that we had numerous problems with the 66s, which gave me justification to switch to the 686s when they became available to us. One of the reasons for my great respect for the L frames is that the issues with the K frames went away with the transition to the 686s.
But even before the opportunity for that transition came available, I was impressed with the L frames. I had owned and carried a S&W model 28, rather than a model 19, because I wanted the extra strength of the N frame. My last personally owned revolver was a model 27, which I still have. I would not have had either if the L frames had been available then.
That is my experience and opinion, but I don't run anything other than factory loads.