What does the 40 mean in 44-40 or 70 in 45-70?

Answer 1

the 40 in 44-40 and the 70 in 45-70 is the amount of black powder that was used to load the ammo. (I think the measurement is called Drams)

With the invention of smokeless powder the 40 and the 70 are no longer accurate but they still keep the numbers to separate it from 44s and 45 which are hand gun calibers

100 years ago there where lots of other ammo like this

p.s. This is not really a math question.