“Forging a decent barrel would be the hard part.”
A Sheriff friend of mine made all his own rifles mostly with a lathe that he shot national matches with.
He was an undercover narc and nothing short of deadly with handguns and rifles!!!
what is the big deal with barrels?
the barrel does not have a serial number,
so it can be bought by mail order,
just like any ordinary machine part.
I've never seen anyone shoot anything with a lathe before, let alone compete with one! That's flat-out miraculous, right there! ;-)