Washington Gun Factory
1) Here's a link to the Washington Gun Factory filmed in 1952
I like the slide rule shown at 2:06. I still have mine from the late 50's and my drafting set made by Dietzgen in Germany - NOT West Germany! And they still work. No batteries to change or corrode, no DRO (Digital Read Out) in those days.
At 8:55 the film shows big cannon barrels, annealing pits, machining lathes, etc.
2) Here is Bill Maloney's list of 245 museums dealing with Military and Naval history. An exhausting compilation. This will keep you going for quite a while.
My contribution can be found at the Aberdeen Proving Ground museum at the 120mm AA Gun portion. https://tinyurl.com/y3tf6yud