I have two of the SP101s. Both are the originals, between 1,500-3,000 were made. I bought my first one brand new, as an FFL dealer years ago. Should have bought a case of them. Barrels are stamped "125 Grain". These are actually 3 1/6" barreled 38 SP101s, that Ruger decided to market as 357 to test demand for a 357 SP101. Because they have a smaller frame and shorter cylinder, a 357 round larger than 125 grain would not cycle. Demand took off, so Ruger spent the $100,000 or so to retool for the frame and th mold for the cylinder.
The 125 Grain version is slightly smaller, lighter and handles great. It recoils straight back into the shooter's hand, for fast follow up shots.
My wife and I both shoot them stock, with 357 or 38+P without issue and she's very accurate with it.
Some say the 125 Grain version is worth more, some say less. Auction sites say more ; )