Originally posted by Sin I AM
whats so hard to understand?...personally i hate using characters with limited appearances or incarnations that are arc specific, there is never really much to go on...he goes from fighting spiderman to decimating panthers army....too much of a varrying degree of power
Because only some Ultron's were actually said to be made of Adamantium.
Even after his initial adamantium appearance, he still kept using very hard metal as his body in same incarnations.
What the Unlimited Arc did, was make all of these incarnations who appeared at the same time into secondary adamantium. Which was like 1 every 10, when there were thousands of them.
Now, it's likely that all these incarnations were just made into secondary after Ultron scrapped the original adamantium for himself, since he had to create every single one over again, and it's unlikely that absolutely none of them were adamantium considering his final form in that arc was indeed "true adamantium".
It never specifically retconned anything. It created talks of a retcon that applied to Ultron specifically, but that's not built on solid foundations considering the context.