First of all, the barrel is designed to accept a particular calibre, so if you have a hunting rifle that is .308 Winchester calibre, that means the chamber inside the barrel is manufactured to accept .308 Winchester calibre ammunition and only that ammunition. There are some exceptions, but broadly speaking, a barrel is designed for a single calibre and the choice of calibre will influence the kind of barrel that the firearm has. Does that address your question?
On December 8th, 2022. See this statement in context.