I get tired of answering this, but here we go again...
Bill Jordan told me in person that he expected some 10-15% of ammo fired in a Combat Magnum would be .357's. Most then and now fire more .38 ammo in any .357 not mandated to be used all the time with full loads.
Some forces now require qualifying with full loads if they are carried on duty. I'd fire them often enough to be sure of qualifying, but not otherwise, unless I needed the power, perhaps in bear or cougar country. In Florida, you might want warmer loads on big pythons. Ditto where alligators or other crocodilians may be a menace.
Now, Jordan said what he did, and he knew what he expected from the design when it originated. But his friend Skeeter Skelton used his M-19's enough with reasonable low end .357 loads that he finally accepted that the M-19 was plenty durable with reasonable use and he largely retired his beloved M-27's for his M-19. But Skeeter used mainly a very hot .38-44 handload that is now considered to be a low end .357 load. I don't think he ever used many 125 grain .357 smoker rounds as were loaded until recent years.
Those appeared in the 1960's, originally under the Super Vel brand.
I used some early Remington and Federal and Super Vel ammo in my M-19's and quickly decided that they were too hot for those smaller guns. I relegated them to use in my Model 27 and 28. Then, I decided that I didn't really need them at all, and went back to 140-158 grain JHP in all .357 use.
From what I've heard, Dallas PD and the FBI both found Winchester's 145 grain .357 Silvertips to be so positive in their effects on felons that I didn't feel the need to abuse my
.357's with 125 grain blowtorch ammo.
In 1981, I was invited by S&W's PR man to attend a session at the sheriff's range where company reps would let us fire the forthcoming L-frame guns. Of course, both the various cops there and I, as a trade press member, were suitably brainwashed with promotional info.
These reps were candid about K-framed .357's suffering from heavy use with the very hot 125 grain and lighter .357 loads. BUT they also told me that a lot of the guns that gave trouble had been shot a lot with Plus P Plus .38 Special ammo. This stuff was loaded only to the specs of the departments that ordered it. It has never been released for commercial sale. The ONLY reason for this stuff is that some agencies were afraid of "community activists" objecting to cops using .357 ammo. So they loaded this very hot ammo and issued it for use in .357 guns. Thus, they could tell the media that they issued .38 ammo. I was told that this ammo was AT LEAST as abusive to K-frame guns as was the hot 125 grain .357 stuff. That it exists and some gets out to the public is one reason why I contest Saxon Pig's posts saying that Plus P, without qualifications, is okay for even early .38 Special guns. Some ninnies don't read ammo boxes carefully and others buy loose ammo and shoot it.
I do believe that dirty forcing cones, with powder residue, increase pressures from hot loads and may well contribute to those throats cracking.
Now, I have recently seen photos of Ruger GP-100 barrels with severely eroded throats from firing a lot of hot 125 grain bullets in .357 cases. If this heavy use affects a sturdy GP Ruger, what do you think it will do to a smaller K-frame S&W barrel with the thinner flat on the bottom?!
My answer is to avoid very hot, lightweight bullets and to use any magnum ammo in reasonable quantities. Occasional firing to remain familiar with the recoil and blast and to be sure it's hitting where it should is enough. Beyond that, use .357 loads in the field as you see the need.
Keep in mind that the good traditional K-frame guns are no longer made. Buy spares and use them in reasonable ways. But I don't worry about firing them in normal use with modest amounts of full .357 loads. I do use 140-158 grain bullets.
I haven't time now to go into why the lighter bullets are a problem. But they are, in full magnum loads. Both S&W and several ammo companies' engineers said so, and told me why.
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Patience, my friend. I believe that one our collective functions in this marvelous forum is to teach.
