Thanks 336a,
Oh yeahhhh..for sure on all that.
Actually, originally, I had realized that ( in my opinion, ) S & W should have offered the "M & P" Revolvers in .38 ACP/9mm Largo, 9mm Luger, and .30 Mauser say, by ohhhhhhhhh, 1904 or so, using Full Moon Clips.
They had the Metalurgy, but I imagine they doubted the Market, and, or, bristled at the thought of offering their Revolvers Chambered for a proprietary 'Colt' Cartridge.
This lead me to wondering towrd maybe someday, electing an early-ish ( say, post 1919 anyway) K-Frame for conversion to either .38 ACP, or, if say a Model 13, then, to .38 Super.
I soon apreciated that the .38 Super Cartridge would probably be too much for a Model 10 Cylinder...or, would be imprudent anyway, in my guess.
Probably converting a 1920s M&P to .38 ACP would be 'iffy'...but, I dunno, maybe could get away with it...if the .38 ACP were kept within conservative bounds.
.38 Special +P supposedly tops out around 21,000 PSI I think.
.38 ACP, 'SAAMI' is 26,000 PSI
9mm, to which various Model 10s have been converted if memory serve, is 35,000 PSI
So...m-a-y-b-e...an older M&P could oblige .38 ACP...or, maybe not.
But it is not too far a stretch anyway, to wonder about.
No +P+ for this child or any of his .38 Specials.