The first Masterpiece revolvers (K-22, K-32, K-38) were produced with tapered barrels and narrow ribs, but their actual loaded weight varied by a few ounces. About 1950 the company introduced the balanced-weight guns, whose barrel design had been reconfigured so that loaded weight of any Masterpiece revolver would be the same. This was done as an accommodation to the target shooters of the day, who wanted as consistent a feel as possible when they swapped revolvers for different caliber competitions.

For several years S&W offered both the light barrel and heavy barrel versions, and you could order the one you preferred. But by the mid to late 1950s, the original design had been allowed to drift into extinction and only the weight-matched designs were available.

There really isn't a particular serial number or date on which the transition was made. There is just a big fuzzy zone where things were all one way at the beginning and all the other way at the end.

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David Wilson