Tom,
I have a Schilke XA1. I tried your suggestion this morning and it works
. I think I'll have my buddy Byron Autry make a set of sleeves ( like Blackburn uses ) for me next time I talk to him. This will eliminate the transposition issue ( Bb to A is the hardest one for me when there's too many accidentals, my brain bites back at me ) and also eliminates the need for a Cornet in C...........which once again begs the question, why build them in C? Why not supply extra slides ( like higher keyed trumpets ) or just build A cornets instead of C?
Anyway, thanks for the tip.
Marty