This is interesting footage. What is quite curious is that this same film, with English captions is posted as "Making an Armstrong Gun", at Armstrong, Whitworth & company, dated in the 1920's. Same people, doing the same things, no change in the plant, equipment or people, even down to the crew handling the gun on the proving range.
Tha Armstrong, Whitworth film has more footage, particularly of charging the Siemens steel furnace (looks like an open hearth furnace, if I am not mistaken). Both crews in the yard loading pig iron into the skip are one and the same, and the captions, translate from the German to English, one and the same.
I wonder whether the Germans got hold of Armstrong, Whitworth's film and re-captioned it for their own purposes ?
The stress analysis calculations for the large gun barrels were likely quite an involved mathematical analysis. How they arrived at the ideas of wrapping the gun barrels with tensioned wire, as well as shrinking on a jacket vs machining the barrels from heavier-wall forgings interests me as an engineer. I know that in the 1860's, in the USA, I believe Dahlgren (or maybe it was Ericcson ?) had come up with the idea of winding wire under tension around cannon or naval gun barrels.
This may have been done in an era when such gun barrels were castings with fairly low tensile strength metal in the walls of the barrels, or some doubts as to consistency of the castings (were there blowholes, sand inclusions, shrinkage defects, or problems with large pours from multiple ladles ?). Winding wire of a known tensile strength and putting a pre-tensioning on it would create a "hoop" around a gun barrel and enable it to withstand higher internal pressures. By the time this film was made, steel making and forging were a well-developed thing. The fact the barrel was made from a large ingot that was pierced and had the bore forged, follwoed by oil quenching and tempering leads me to think the barrel was a high grade steel. The German film does refer to shrinking on the "mantle" (German for "jacket" or "coat"), as does the Armstrong-Whitworth film. Same footage, different language captioning.
It just seems like making more work to shrink on a large jacket, rather than simply make the barrel as a one-piece forging.
The interesting thing is the progress of weapons has obsoleted the large bore guns, along with the battleships (or "Dreadnoughts") or gun emplacements. Various missiles have pretty much taken over. Instead of needing a massive gun emplacement, railway mounted gun, or a battleship as a platform for the guns, a relatively lightweight missile launcher and missiles do a much more effective job. The idea of a "smart" projectile with the kind of punch some of the missiles pack would have seemed unbelievable to the military and ordinance people in the era of this film. Missiles with conventional warheads, launched from mobile equipment like trucks, full tracked carriers, or from light surface vessels or aircraft have completely changed the way wars are waged, and have more than levelled the field in some regards. In the era of this film, only countries who could afford to build and arm capital ships with large guns, or build railway mounted guns (the German caption calls this a "travelling gun", if I recall correctly), could have the heavy armaments. We would later come to call such nations "super powers". When missiles got into common use, nations that would not have been taken seriously in the era of battleships and heavy guns suddenly were able to wage war against the superpowers. A case in point was the Falklands War. Leaving politics strictly out of this, consider the Argentinian Navy sinking a British frigate or destroyer (HMS Sheffield, I believe). No heavy cruiser or big guns, but an Exocet missile. The idea of the Royal Navy losing a ship to a country that had nowhere near the naval power would have been unthinkable, if not an impossibility (short of using a submarine and torpedo attack) in the big gun era.
The era of the big guns and the various platforms to bring them to bear is long done with. I remember in 1972, when I first got out of engineering school. I was assigned by Bechtel to work on a jobsite at Potomac Electric's Morgantown (maryland) Generating Station. Across the Potomac River on a kind of diagonal from PEPCO's plant was the US Naval ordinance testing station at Dahlgren, VA. At various times during the days and into the evenings, the Navy seemed to have no end of ammunition to fire off. Everything from machine guns and anti aircraft guns to big naval guns. When they'd fire the big naval guns, the concussion would arrive at PEPCO's plant. If you were inside their powerplant (a coal fired plant), the dull concussion against the siding of the building would raise little puffs of flyash that had accumulated on the structural members, piping and odd places where no one cleaned. In the evenings, if the weather was nice, we'd go to the oil dock (where Stuart Petroleum oil barges unloaded fuel oil). PEPCO's plant was mainly coal fired, but they had a tank farm with a lot of oil storage for startup and for running gas turbine peaking units. We were extending the oil unloading dock, so I spent some time there. Evenings, if not much was doing, a couple of rods and spinning reels and lures were kept in the oil barge unloading dock operator's shed. We'd get the rods and sit on the oil dock and cast for rockfish (striped bass that come upriver in the brackish water), or perch. Mostly, it was catch and release. While we'd be fishing, the Navy over at Dahlgren often put on a show. Sometimes, they'd shoot up parachute flares, then lay on a barrage of anti aircraft fire with tracer rounds. We'd sit on the oil dock and fish and discuss what the Navy was up to. The consensus was they were shooting off "retrograde" ammunition to get rid of it. I'd often remark that high powered sporting rifle ammunition was expensive enough as it were, and that I would trade them my annual paycheck for the cost of the ammunition they were going through. Now, with missiles, I imagine there is little shooting going on a Dahlgren. Similarly, in the machine shop at PEPCO's plant, the senior machinist had come out of the US Navy "gun factory" in Washington, DC. PEPCO had a well equipped machine shop with a new American Pacemaker engine lathe. I was in there once to get a piece of steel turned down for a pin to go through sheaves on the block of a construction crane, and the senior machinist did the job "1-2-3" in the American Pacemaker lathe, telling me proudly that he'd come out the Naval Gun Factory. Other than photos and some film footage, I am sure the Washington Navy Yard and the gun factory within the yard are long gone. Missiles built on light-weight CNC machine tools and launched from very light means can do more damage more precisely than the big guns like this film depicts.