48 rounds of Enfield Cartridges in this British design cartridge box weighs in at 4.18 pounds. The individual cartridges are 610 grains, X 48, divided by 7000 (7000 grains in a pound) = 4.18+ pounds.
The cartridges have a 523 grain bullet, 60gr of BP, and adding the paper involved.
An original Enfield cartridge would have a 530 grain bullet/wood plug, 68 grains of course grade BP, and the paper added for weight.
It's heavy after carrying it around a bit!