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In "The Wolverine", during the final battle, the Silver Samurai heats up his sword and cuts off Wolverine's Adamantium claws:
Then, after the Silver Samurai has been injured, Wolverine grows back his original bone claws:
But, in "Days of Future Past", Wolverine has his Adamantium claws again. There was no real explanation as to how he got them back, as he still had his bone claws at the end scene where Magneto and Charles Xavier come to see him.
So what is the in-universe or out-of-universe explanation for Wolverine getting his Adamantium claws back?