Here is a selection of factory drawings/blueprints for how Eley Bros made pinfire cartridges. These blueprints date to the early 1900s.

First up is the 5mm pinfire cartridge drawing. There is a lot going on here! It lists the dimensions for the bullet, the pin, the percussion cap and the case. They also give all of the dimensions in imperial units though these cartridges were always sold by their metric designation, “5mm.”

The bullet is described of being made of 98% lead and 2% antimony. The antimony was an additive used to harden the alloy. It was a hollow bullet with an overall diameter of .207 inches, or 5.258 millimeters. It had an overall height of .300 inches or 7.62 millimeters. The bullet weight is 18 grains and the powder charge is listed as “about 1.5 grains.”

This matches up closely with examples in my collection which have a bullet weight of 18.0 grains and a powder charge of 2 grains. The overall weight is 35.2 grains.

The brass case is listed to have a mixture of 70% copper and 30% zinc to make up the alloy they used. The case had an overall length of .450 inches or 11.43 millimeters. They give the exact specifications of where to put the hole for the brass pin and even what angle the pin should be placed in the cartridge to ensure the hammers get the best hit.