I've "adjusted" a couple of mine to fit the larger bell on the B1. I added a thin "shim" of cork so that the cup mute wouldn't hit the bell. (No, it isn't "tuning" the way you meant")
You know that a mute changes the overall intonation of a horn; straight mute sharpening it, cup mute flattening it (at least, I "think" that's what I've been told). I believe that you just add/subtract "cork" until you find the change of intonation to be at a minimum.
It's interesting that I had to adjust my mutes for the Shilke (they had been previously used on a 37ML180). I was a bit concerned when the MR came "into the household" to the extent that I was prepared to buy a second set of mutes. Turned out I didn't need to.... they worked fine in the MR.
