Didn't read through the whole thread... Sorry...
But, there are well over 50 different 6.5mm caliber (.264") cartridges. I wouldn't be surprised if there is more than 60 ( 6.5mm ) cartridges. Many are probably obsolete... however there is probably 30 or so 6.5mm / .264" chamberings still being used today.
This is the problem with most folks using the word caliber when they're talking about a cartridge / chambering.
Even then,... a 308 winchester / 7.62 Nato, is the same caliber as a 300 WinMag and a 30'06. It's just a name.
At the range when someone asks me "what caliber is your rifle", I answer, "30" or 24" and a couple seconds later I say 308 Winchester or 243 Winchester etc..
But, there are well over 50 different 6.5mm caliber (.264") cartridges. I wouldn't be surprised if there is more than 60 ( 6.5mm ) cartridges. Many are probably obsolete... however there is probably 30 or so 6.5mm / .264" chamberings still being used today.
This is the problem with most folks using the word caliber when they're talking about a cartridge / chambering.
Even then,... a 308 winchester / 7.62 Nato, is the same caliber as a 300 WinMag and a 30'06. It's just a name.
At the range when someone asks me "what caliber is your rifle", I answer, "30" or 24" and a couple seconds later I say 308 Winchester or 243 Winchester etc..