I do not have a clue what was done in the old days, but I can say that all the 12 & 20ga shotgun barrels made in the 30+ years were made in house. They also make finished OEM barrels for several other mfgs, provide barrel blanks and have made every replacement barrel sold under the "Hastings" brand name.
Barrels are hammer forged, and yes I have seen the machines although I do not have the exact date they were installed.