After doing a looking on the internet, it appears that the S&W is a Model 3. Apparently, that was the first DA that S&W made. Originally they were big bore six shot revolvers, but then were produced a "packt pistols" in 5 shot variations in .38 and .32 caliber. I'm not 100% sure on this and will have to verify it with an expert. Since the .380 round is just a little too large, it probably is a .38 calibur.