I think the newer process is called ABL (layered?) The old ones are just nickel on the base metal. I have one old LA .25 that is actually blue, but it works good. Maybe the problematic ones weren't etched properly for the nickel, but the copper sticks well and then the nickel onto that. I think the hotrod stuff polishes the copper. It would be copper nickel chrome. The chrome does peel without the bumper even getting hot. I only did chromate and passivating at work. It could be troublesome when the tanks got oily or used a lot. Even chrome liners can peel in some batches. Fox tried and gave up in the end.