Question about Pitting

Hello Guys,

Can someone tell me how a gunsmith can remove light or heavy pits from a pistol? I wonder if there is a "filler" that they use to fill in the pits, and if so where can I obtain this filler. Would it something like "liquid steel" or a product like that? Maybe Thor should answer this question since he has done magic with old pitted Lugers and made them lik new.

Thanks. Bob