A worn blueprint with clear but rough markings, as if drawn not by engineers but by people who desperately needed to survive.
It shows the basic parts of a cartridge and a simple assembly process.
Every component requires precision—mistakes are unforgivable here.
The page is scorched in places, as though someone had tested the design in real life.
In this world, such a blueprint is not knowledge—it is a risky chance to fire another shot.