The now-neutered current SAAMI-spec 357 Magnum loads (36K PSI rating) won't do harm to K-frame 357 Magnum revolvers. The older ammo that ran 42K PSI might strain them after a while, and weren't much fun to fire in K-frames anyway.
This is per the Factory to my agency when we added the 357 Magnum to our approved-ammo list in 1994. Same story for the J-frame 357s, current SAAMI-spec won't hurt them. I don't enjoy the ammo in a J-frame, but that's another story.
Our carry load is the W-W 158 grain JHP, BTW.
When I got into the LEO bizness in 1977, the K-frame 357 Magnum was THE revolver to own and run. Period. Pythons got a little love, too--but I couldn't eat and own one at the same time. At the time, 38 Special +P was the authorized ammo, and it was a good match for the 13/65/19/66 platform. MANY deputies carried a 4" 19 or 66 in uniform, then used a 2.5" version off-duty or in plainclothes. If you liked to shoot targets or hunt, the 6" was around, too.
I never really "got" the idea of a 2.5"-barrelled Magnum until I had a chance to run a Model 13 x 3" that a range rat buddy of mine from FBI let me borrow for a time in the mid-1980s. THAT THING WORKED. Very well.
I had that in mind earlier this year when a Model 19 x 2.5" became available at a good price. I snagged it, and a Bianchi #7 hip holster followed soon thereafter.
Just like the Model 13, to 25 yards I can't miss with this revolver. Running my carry loads or loads that duplicate same, the short maggie is all a retired lawdog really needs.
My prejudice, for the record--had my agency approved the 357 Magnum in 1987 at the same time they added autopistols, I wouldn't have switched platform type to bottom-feeders. I would have just done an ammo upgrade in the 686 and called it good.