Our Beretta Paralleli Societŕ researched barrel provenance for a newsletter article last summer. Here's an excerpt...we'd appreciate any corrections or enhancements :-)
Throughout the last century, it is somewhat uncertain what years Beretta received pre-bored cylindrical billets from steel mills (or Liege mechanics), and when they began receiving raw ingots of steel to shape, bore, and finish in-house. In 1881 Giuseppe Beretta published a document saying “I alone undertake the complete manufacture (of shotguns), while other Brescian firms do not make their own barrels, but buy them ready-made.” However 30-odd years later American Rifleman researched the shotgun barrel supply chain and determined that "to avoid overheating during the brazing process, makers of Anticorro, Krupp Special, Witten, Excelsior, and other high quality steels refused to sell shotgun barrels as single tubes; they sold them only in pairs already fitted together and finished – with the exception of chambering and bluing."
Fluid steel had been around since the 1860s (Berger, Whitworth, et al) but was becoming more prevalent in the early 1900s and the process of forming barrels evolved and became more complex – driven by developments in the tools of the trade, drills, grinders, lathes, etc.. In 1903 Beretta had ~130 employees in ~100,000 square feet of factory space and may have lacked the tools and machinery to work fluid steel. Given that Beretta cataloged and sold entire guns made by other firms at that time, it is not unimaginable for them to have bought mostly finished barrels for their shotguns.
Between the wars mechanization became prominent in the arms business. Steel ingots were cut and transformed into smaller cylindrical billets which were typically shipped to a machinist to rough-form blanks or tubes according to the gunmaker's order. A typical tube making process was to achieve the desired length by some sort of forging process or forge passing operation, which compressed and hardened the steel, then bore a pilot hole. Then they would begin the hole enlargement process. Next came the exterior grinding, profiling, and outside turning. Then they were back to the gun maker’s specific gauge/profile requirements. After that they were back to the external profiling followed by internal polishing/lapping which was accomplished by women or children. Last they were back to the exterior. Finally it was sent to the proofhouse. At this stage, it is known as a tube or a barrel, forged and rough bored barrel.
