Hobbsy:
If the cylinder was chromed, it's hard as hell. At the factory, it was either honed or lapped (probably lapped) to it's proper size. In a run-in, the "give" would have to happen on the piston-side of this mating of parts. In order to "run in" to make a better seal, there HAS to be a harder material and a softer material to mate with it. The ABC, ABN definition (as I'm sure YOU know), is as always: Aluminum piston, BRASS cylinder liner, Chrome/Nickel plating. NO annealing occurs with the brass cylinder liner.