Some may disagree, but my opinion from my reading of the old timers like Bill Jordan, the K frame magnums can be looked at like 38's designed to withstand 357 magnum pressures
to a point, that being, it became clear early on that the frames would not stand up (as well) to an exclusive steady diet of stout magnum loads. The guns would "shoot loose".
The gun was designed to handle full power loads safely but was designed more in mind for ease and comfort of carry on a daily basis primarily by uniformed police officers as holstered sidearms. If anyone originally ever had any idea that these guns were to be used exclusively for magnum loads and shoot thousands of rounds like that, I believe they quickly revised the opinion once they observed the real world results.
Then in the 60's-70's when the Remington 125 grain police load was introduced it was found to be very effective in police documented shootings. But the forcing cone complications were soon discovered and that is where we are - thousands and thousands of K frame guns out there decades later among humans who decide that whatever something was designed for, it can always be pushed a little harder.
I don't know how many 44 magnum shooters I have met that aren't happy with factory ammo performance and insist on shooting hotter and hotter loads. To the point where S&W had to beef up the model 29 with an "endurance package". Nothing wrong with wanting increased performance - my point is just that trying to turn a VW Beetle into a rail dragster doesn't work. Restrained by the limitations of it's design, it eventually reaches a point of performance where things start to break from pushing the envelope.
As I said, some may disagree, but in my opinion, if you insist on firing hundreds and thousands of rounds (and very few shooters actually do) of full power magnum loads, don't expect a K frame S&W to stay tight and safe for an indefinite number of rounds. The L and the N frames were designed to accept the punishment of the 357 magnum round more so than the K frame. Everyone knows at least one wag who insists
" I've had this model 19 for 40 years and I've shot 47 quadrillion magnums through it and it's as tight as the day I bought it !"
Yeah, right . . . . . .
And I have 19 with a replacement barrel in it ( that I was lucky to get) courtesy of someone who fired one too many light bullet/high pressure magnums through it and split the original barrel. Yes, you can push them past what they were designed to do - doesn't mean it's smart and there won't be consequences. If you're lucky, the gun is all that will be hurt.
Didn't mean to post a rant or step on the OP's original questions (which I did not really address); it's just inevitable when talking about 357 magnum loadings and bullet weights that these things always come up.
