bushveld,
In looking back over this thread, I realized that I had not addressed your question of why rifles with 9mm or near 9mm bullets are called 9.3mm. There are enough cartridges involved that I don't think just one reason will be an adequate answer. This is common with cartridges that started as black powder fueled and went to smokeless; not necessarily because of the powder itself but also because of changes (improvements?) in materials, customs, dimensions, etc. in common use at any particular time while the name of the cartridge stays the same. Muzzleloading rifles often used bullets smaller than groove diameter, even smaller than bore diameter. When someone decided to put everything together in a package (cartridge) they used the procedures they were used to. With black powder and soft lead bullets that worked, after a fashion, because of obturation. The pursuit of higher velocity and more efficient bullets have led to many changes in materials and dimensions while the name stays the same or the dimensions stay the same while the name changes. Everybody is trying to sell rifles/cartridges, and more powder, more convenience, or a better sounding name helps them do that. The nominal designation of a cartridge often no longer matches the actual dimensions, sometimes it does. The answer is: There is no enforceable rule that everyone agrees to. This applies to metric cartridges, as well as imperial and it is the same with new cartridges. A 6.5 mm bullet is not 6.5mm in diameter and a 38 caliber is not .380" in diameter, also a 350 Legend bullet and 360 Buckhammer bullet are not markedly different in diameter......That is what makes this game fun.
Mike
Last edited by Der Ami; 03/03/25 11:52 AM.
