SBruce, you are missing the biggest difference. The 284 Winchester has a .284 diameter bullet (it's a 7mm). There is no 6.5x284 Winchester cartridge (official, registered cartridge, that is, that I know of) only the plain old 284 Winchester. The 6.5x284 Norma has a .264 bullet (it's a 6.5mm).
They are different size bullets (and the Norma specifies a longer overall length). If you were building a modern .284 Winchester on a bolt action, there would be no reason to set the COAL so short, unless you really wanted to keep it short to fit a short magazine.
Im not really building, but rebarreling a LA savage to 284 win and im going to have the throat LONG!! just to give an idea, the 195 grain EOL's boattail/shank junction is going to be above the neck/shoulder junction. OAL will be approx 3.33If you were building a modern .284 Winchester on a bolt action, there would be no reason to set the COAL so short, unless you really wanted to keep it short to fit a short magazine.
I attempted alot of research on this just a couple months ago.
The currently recognized version was adopted by Norma, so sometimes it will say Norma on the item. Sometimes just 6.5-284, but it's the same thing.
My 6.5-284 Lapua brass says 6.5-284 Norma on the box and so do the Redding dies.
Some guys may use Winchester 284 brass and actually neck it down, but once it's fired in the newly adopted chamber it becomes 6.5-284 Norma anyway.
Near as I've been able to tell or research, there is no appreciable difference in the modern version. I might be mistaken, but I think anymore its all simply 6.5-284.
Would be great if someone would post a cartridge diagram of 284 winchester vs the current version, but I haven't seen any such thing.
Just use the norma Reamer and be done with itIm not really building, but rebarreling a LA savage to 284 win and im going to have the throat LONG!! just to give an idea, the 195 grain EOL's boattail/shank junction is going to be above the neck/shoulder junction. OAL will be approx 3.33