Lead shot technical advice
Antimony is a silvery-white metal – in its pure state, its hard and brittle.
It is lighter than lead, and has a higher melting point.
Alloyed with lead in small quantities, it has a considerable hardening effect and hard shot has good ballistic performance because it is not easily distorted out of spherical by firing pressures.
If you look at Charless
review of partridge cartridges, you will see that the antimony content in all the cartridges tested was 3%.
Thats about right for game cartridges. The antimony content of competition shot is often a bit higher, but rarely more than 5%.
Shotgun shot is not the only use for antimony/lead alloys – the lead plates in your car battery are made of the same stuff too.