That's a well fed lady wielding that rawhide mallet. That'd certainly get the tightest cover fitted! Photos 2,3 and 4; breech blocks.
Photo 3 looks like she is cutting a flat that ends in a radius, where the next operator would presumably use the gang miller to cut the feed horns, ejector slot and magazine clearance. That was done in one hit. Note the partially finished BBks on the table. Probably to illustrate what she's doing.
Photo 4. Is she cutting the front radial bearing surface? I interviewed a really nice fellow who contacted me. He was an apprentice and as such had his call-up deferred. As he was skilled, he was responsible for accurately setting the breech block making machines. Got called up eventually.
Better not let F-10 see those photos with all those unguarded belts and cutters. And where's the walkway safety lines that should be painted on the floor in photo 2? Makes you wonder how we ever waged an all-out war doesn't it....... And won it!