S&W told me that M-60-4 and later M-60 revolvers received added heat treatment and maybe newer steel alloys to warrant guaranteeing them (Rating) them for Plus P use.

But it seems the consensus that S&W is correct to say that their guns made after 1958 are also safe with Plus P in reasonable quantities. The -4 and later will probably just last longer with hot ammo, before developing cylinder endshake, timing problems, etc.

The late gun writer Jeff Cooper said that he handloaded very hot charges of Red Dot powder to get around 1,000 FPS with cast lead 158 grain bullets in his M-60. This was in the 1970's. He had no trouble, but never said how often he fired those very heavy loads in any one gun. I doubt that he practiced a lot with them, but they proved safe in his guns, for at least occasional business use.

Speer told me that both NYPD and LAPD ISSUED their 135 grain Short Barrel .38 ammo in ALL remaining .38 guns. They told Speer-CCI that the ammunition performed very well in actual shootings. It's what I use in my snub and three-inch (M-60-4) guns and in my Ruger SP-101 .357 for indoor use.

Speer further advised me that their Short Barrel loads were fine in barrels to four inches. They did not recommend them for longer barrels. I load their 125 grain Plus P in longer guns. Actually, I load it in my M-66-3 and my GP-100 for indoor use, as in home defense. There was a time when I used it at work, too, unless I was working an outdoor location where I might have to shoot into cars. Then, I used full .357 ammo, usually Federal's 158 grain Hydra-Shok or Winchester's 145 grain Silvertip. I carried these .357 rounds where I might have to shoot a big dog or other dangerous animal.

A detective checked ME files for me to see how well that 145 grain ST worked in police shootings and those by FBI in our area. Both FBI and Dallas police issued that round to personnel carrying .357 ammo. He said it was grimly effective, almost too much so, whatever he meant by that. I'm less squeamish.

Your M-19 will probably only risk splitting the forcing cone if you fire the very hot 125 grain and lighter Magnum ammo, and similar very hot handloads. If you feel a need for this sort of ammo, get a GP-100 Ruger or L r N frame Smith and use it in moderation. I have seen photos on both Ruger boards of GP-100 forcing cones that were very badly eroded by use of this very high velocity, light bullet ammo. There is a trite saying that Rugers are built like tanks. Not so. They endure longer than S&W guns in heavy use, but you can wear out any revolver if you really go at it!

Your M-19 will fare well with 158 grain bullets, in reasonable use. The designer of the gun, Bill Jordan, told me personally that he envisioned firing full .357 ammo in them just about 10-15% of the time. Be guided accordingly.