Forging is an "oldie but a goody".

The process of belting a hot piece of steel into a general shape imparts some interesting "alignments" in the internal crystal structure. This is a good thing. Sometimes it takes several re-heats and a couple of sets of dies to achieve the final shape that is then finish-machined where needed. Think about all of the "drop-forged" wrenches etc in your trusty toolbox.

Apparently the constant, regular pounding of the big forging plant at the old Lithgowicon factory could be heard and felt for quite a distance around when it was running.

The receiver body of the Bren started life as a forging. It takes a very big hammer to bash out a shape that big.

Lee Enfield receiver bodies started out as a vaguely recognizable forged blob. Then the machinists cut away everything that didn't look like the desired end product.

Out of necessity, a lot of "high-tech" found its way into the gun-making business during WW2.

There is a famous, possibly apocryphal story about all of this:

During WW2 GM engineers went to Colt to look at the works before taking up a contract to make Browning-pattern machine-guns.

At the end of the tour, when asked for some thoughts, the GM engineer said something like: "You guys don't make guns, you make swarf; guns are your by-product!"