The gun, its parts drawing down to the tiny pin level, jigs, test equipment, material used in every single part, their qap , testing process for each single part , material process chart et al , vendor list, who make what etc just some things off my head i guess. material qap alone is quite large, we are seeing konkurs m docs from BDL for decade now and yet every time some new part doc comes out.
Plus add the appendix part. That alone is meant to ensure that a reader with rudimentary skills is able to grasp the message. That's huge.