Thread: 6.5 v 7mm

Greetings All,
The calibre controversy has been going on for a long time. Up until WW2 smokeless rifle cartridges were mostly named for the bore dia (land to land measurement) hence .270 or 27 calibre, 7mm or 276 calibre. Post war some US cartridges started being named for groove dia .243 for 6mm or 236 calibre and .308 for 30 calibre. All this has got hopefully confused and the table in Wikipedia mentioned above is worse than useless in adding any clarity. With pistol and small rifle cartridges that were developed in the black powder era the situation is even worse and I wont even go there.
So sorry Micky your beloved .270 falls about 0.02mm shy of being a true 7mm calibre. It probably owes its existence to the US reluctance to use anything metric (softening lately) and Winchester picking the next calibre down from 7mm as .280 was already in use.
Regards Grandpamac.