This from a March 1, 1934 letter from D. B. Wesson, then Vice President of S&W, to a customer who has ordered a pair of Outdoorsman----one .22 and one 38/44----for the hot rod .38 Special cartridge immediately preceding the 357 Magnum, and the +P from a time when there wasn't one (and the revolver which then and now was and can be re-chambered and safely used for .357 Magnum ammunition). In so many words, he says the steel as it comes from their suppliers is safe for use in any caliber weapon they make----with no strengthening whatsoever.

His exact words (in response to the customer's inquiry as to whether or not the cylinder of his .22 Outdoorsman will be heat treated): "The steel that is used in the cylinder of the K-22 is identical in formula with that used in the larger calibers, but it is not heat-treated after machining as the great thickness of the cylinder walls do not demand any further strengthening. As a matter of fact, even in out larger calibers the steel as it comes from the mill shows a tensile strength in the neighborhood of 80,000 lbs., which does not make the additional strength gained by treating a necessity, but we do very much prefer the greatly increased factor of safety that is obtained with the 130,000 lbs. elastic limit that the treating gives."

Bottom Line: It would seem +P is more about more money for the folks that make it than anything else.

Ralph Tremaine