I prefer stainless over aluminum cylinders and had issues with my 43c sticking. Would a steel aftermarket cylinder for a 651 kit gun fit the 43c? If not could custom steel cylinders be made or the best bet just to ream the aluminum one?
Oddly, at least in my mind, the 43c has a cylinder length of 1.53 and the 22 mag 651 is 1.44. Someone should be able to speak of interchangeability, but are you more interested in shooting 22 mags out of a 43c or just want a cylinder that extracts fired cases more easily?