I inherited one. A two inch, blue, M&P .38 spl. Airweight.... (pre-12). Father-in-law's that he used in Law Enforcement many, many years ago. It's probably 1955-1957 manufacture. No model number, C serial. Very nice revolver. The light weight is wonderful for carry. One serious drawback is that, being an aluminum frame, use +P ammo is a significant factor for frame trouble. And barrel or frame cracking is a significant risk.

I would use light loads or any "standard" load or handload but steer clear of heavy loads or any high pressure ammunition. Other than that, they are a really nice revolver.