I've got a nice early 90's Model 60 all stainless steel .38 Special and just bought a new 637-2 Airweight .38 Special. My question is: How is it that the Model 60 is not +P rated, yet this new 637-2 Airweught is so rated. I can't figure it out, or is it that S&W just didn't use the +P rating as a marketing description in the early 90's?