Holy crap, that guy is talking about amazingly complex things like they're as simple as tying your shoes. Boring it out is one thing, but "Yeah, I'll just change this from a rim fire to a centre fire by adding a firing pin..." and "I'll just need to basically rebuild the extractor..."
(!!!)
Tip of my hat to him for knowing metal that well to just basically make an afternoon project out of something that involved like I would paint a wall.