Ken, Your the first one to pick that up... My S&W 58 1/2 started life as a model 29 that suffered from the problem of unlocking when fired and the next shot was on the fired case. When I saw a model 57 cylinder and a model 58 barrel for sale, I figured I will make the problem 44 into a 41. The finished gun has 58 barrel with the adjustable sights of a 57 hence the 58 1/2. I know... a little crazy.
I agree 100% .410" sizing. All my 41`s are accurate. The model 83 shoots like a "secret weapon"....