Coupla' things to consider;
Most of what Terry M. said I agree with.
Rather than being "wed" to a single gun, I've crossed paths with a number of .357 K-frames.
IMO, the problem with the wear issue was due to some really hot ammo produced from the early '70's till the mid to late '80's, when a lot of .357 ammo began to "cool" down at the factory level...
It was found that a lot of the "hot" ammo, particularly the 125gr JHP loads were producing well over 50,000 psi when the technology became available.
SAAMI specs have been lowered somewhat for the .357, and the "wear" factor on the K-frames is largely "lore" now.
I have seen some top straps "flame cut", forcing cones split-and/or eroded.
These were L.E. range guns used for training/testing/qualification purposes and often the described "problems" were the result of over 50,000 rounds fired.
I had a 686 (m)4" (an L-frame); (first issue with "recall" stamp added after modification- (hammer nose replaced- primer cratering due to those loads I mentioned!).
After ~50,000rds, approx. 3,500rds of Magnum- (rest .38spl), at least 800 of which were the 125gr.JHP Winchester at 1,450fps (chrono'd!). It had erosion of the forcing cone that was noticeable if examined. I set the barrel back 1- turn, and recut to 11deg. It was still "tack driving' and capable of "winning" an NRA service gun match, of which it did numerous times. It had approx. .005" of flame cutting.
K-frame battering is not as "big a deal" as those who want to talk it down prefer.
With current SAAMI max and using some of the faster burning powders... such as BlueDot, and even Alliant 2400, you'll probably never see problems. (Max load of H2400 in '70's was 15.5gr, with some loading 16.0!-current favored load is now 14.5), I've seen 21.0gr of Win296 being loaded under a 125gr Zero JHP on an "automatic" loading machine!! <not at Zero,Inc.>)
Even if you do have problems, like with Terry's gun, it'll probably either be warrantied, or fixed cheaply.
The erosion issue is greatest , for the reasons others mentioned, with large quanities of relatively slow burning spherical powders and high velocities, and light bullets. The forcing cone splitting is largely due to heat stress and alteration of the heat treating (becoming brittle) combined with the hardness of the jacket material. Seldom if ever seen where heavy lead bullets are used.
The flame erosion of the top strap usually stops after a depth of ~.010", and I've never seen one that was cut to where it was unserviceable. A range gun I was shown once had over 100,000rds through it; had been rebarreled, and previous barrel set back till it was unserviceable, and had the .010" gas-cutting, and was still "On the job".
If you like the feel, and size of the K-frame, get it....
Thats what the K-magnum's all about. It'll do for most any purpose you might put it too.
