I believe most of the wear and/or damage occurs on the male tenon on the neck, That I.D. is a bit tricky to measure with calipers. My mentor taught me to use a T-gauge which is easier to control.I simply cannot believe this! I measured mine and it was ............24.17!
How on earth there can be that level of consistency?
I agree with that point about the wear. But what really amazed me was that two saxes built the best part of a century ago out of relatively soft metal could have been made to such close tolerances. 1/100th of a mm is a pretty tight tolerance. Maybe it was just fluke that they were identical.
It was funny, I couldn't believe it when I looked at the vernier caliper.Not totally a fluke, but this one was funny, being dead-on.
Generally speaking (I refurbish vintage horns) if you have 2 horns of same model, in order for one tenon to work in the other horn the tenon measurement has to be within around .2mm or so, max. Anything more than that and it makes it very hard for a tech to tweak one tenon to fit in the other receiver.
So, I have found that generally the tolerances on the same model horns, even spanning a generation or more, are usually inside of .1mm. Pretty much across the board really (unless there was a known design change).
So a '37 Conn 6M's neck is gonna fit a '67 6M's receiver, with either no, or minimal, tech adjustment. A '47 Martin Indiana neck is gonna fit a '68 Indiana, etc....for most mfr's, American or European, this is the case....