I noticed that the S&W site list there being only 21 inch sizes, but the ones from Thread Tool Supply have 23 inch sizes. The metric are both 21 sizes.
Hey me too!, got mine yesterday, took about 2 weeks from US to oz, cost $95 for the pair delivered, very happy with the quality. I made my own set years ago but they look rather shabby next to these ones.
But like Exceller8 says "made it 30 years without it". I don't fumble with that stuff as much like i used to. But if the price was right i hang one. If worst comes to worst I could use my thread gauge in my tap and die set.
For some reason it makes me remember one of the first projects I had in high school metal shop back in the day. We each made a tool guage that had a V cut in one end with the proper angle for sharpening bits and various threaded holes put in it to determine thread and bolt size. However thats nice! Good thing I don't have $70 bucks burning a hole in my pocket now... I just got robbed by the tax man and I"m cleaned OUT.