sleeving down a squish band

I have to sleeve down the ID of a squish band that was previously opened up for a larger bore (unknown history). Brass works well but has anyone tried steel or alum? Results?

I have a Commando head on Atlas barrels. I had a guy insert an aluminium ring into the recess where the spigot of the Atlas barrels used to go. It's been in there a few decades so I'm happy that aluminium works OK.