The process involves disassembling fired cartridges, cleaning and inspecting the brass casings, replacing the spent primers, carefully measuring and adding new propellant powder, and then seating a new bullet into the case. This results in a fresh cartridge, ready for firing. For example, a .223 Remington cartridge can be disassembled, its components replaced, and then reassembled to precise specifications.
The practice offers cost savings, allowing shooters to create ammunition tailored to specific firearms and shooting disciplines. Historically, it was vital for individuals in areas where commercially manufactured ammunition was scarce or prohibitively expensive. The ability to customize bullet weight, powder charge, and other factors provides significant advantages in accuracy and performance.