It’s just fascinating what humans have done with their rationalization at the time to design a very complicated system in firearms nomenclature. Lower animal carnivores have it down to the basics: “It’s meat, let’s eat it”.
But just why are we so basic in the shotgun area with only 10, 12, 16, 20, 28, 67.5 (.410) gauges currently built and commercially loaded for?
If you look at the current commercially loaded American centerfire rifle cartridges, there are 96 different calibers in the latest edition of Cartridges of the World. I can also immediately think of at least 3 more since that edition came out. And each of these are unique, they can’t safely be fired in another caliber rifle.
The reason can’t be to keep a performance difference between the gauges, as many of the various different rifle caliber cartridges have minuscule or even non-existent ballistic differences. And you can’t say it’s because of the widely available different load weights, shot sizes or powder charge choices for each shotgun gauge providing enough overlap, as for each of the rifle calibers there are different bullet weights, shapes, internal construction methods and now even different powder loads.
Compared to the rifle guys we have made it somewhat boring, to have so very few gauge choices to play with.
