Ah, my ignorance of the trade is not far beneath the surface, but I'm under no illusion of men swinging hammers!
I'm trying to understand the different barrel manufacturing methods. For instance barrels forged around a mandrel versus barrels that are drilled and honed. In the case of the latter, how are the chamber, forcing cone and choke achieved?
In the case of a (cold) hammer-forged rifle barrel, a barrel blank with an oversize bore is actually hammered radially inward against a mandrel that is the "negative" of the bore, thus producing the lands and grooves at the proper diameter.
I'm unaware of any shotgun barrels that are made with this method.
Shotgun barrels, whether bar stock or a forging, are first drilled, then reamed and honed to final bore size. The chamber and forcing cone are cut with reamers made for the purpose. If the barrel will have a fixed choke then the bore is drilled, but not reamed for its full length, leaving a portion near the muzzle a smaller diameter. This is finished with reamer and hone to a diameter that establishes the choke.
