Unfortunately, the nature of a semi-auto does not promote the use of multiple calibres (like a wheel gun does) w/o changing barrels, extractors, ejectors, etc. (and even then it's not possible with most semi's - Glocks being the primary exception.) Having said that, I'm not certain that even the VERY few autos designed to shoot 357 Magnum will reliably or accurately fire 38SPL. Too much reliance on the extractor for head spacing and too much "leade" (a fancy rifle term referring to the unrifled part of the barrel near the chamber which can negatively affect accuracy.) Not to mention the 1/10" (or was it 1/8") difference in cartridge length which I would think would cause magazine issues.
You're signature is awesome.
"THE GLOCK STAY WITH ME, WE FRIENDS 'TILL THE END." -Curtis Jackson
Sig Sauer Club #108, Top Guns .357 Sig #109,
Heckler & Koch Club #110