Anybody familiar with the "7MM Medium" cartridge? This is not a description of the cartridge, it is, AFAIK, the actual name of the cartridge. I saw a picture of it on this website: http://www.quarry.nildram.co.uk/Assault.htm
It was a proposed assault weapon cartridge that was never adopted. I used the search function, but couldn't find anything.
It's one in a series of Brit experimentals that ended when they adopted the US 7.62 NATO. The .280/30 is probably the best known of the bunch. Canada and Belgium both got involved on a limited basis. The 7mm Medium was actually adopted by Venezuela, for about 5 minutes.
As I understand it the 7mm medium was the British .280 (7x43mm). The 7x49.15 (7mm "Liviano") was the one adopted by Venezuela. As far as 7mm rounds go, the 7x51mm (AKA the 7mm-08) was one of the best rounds ever created, it was an attempt by Britain, Belgium and Canada to create a round that America would accept that was a 7mm. The US wanted a full power round with a 150gr bullet, and if you want that bullet weight a 7mm will give you a coefficient of .5 with a good bullet design. The US didn't go for it because;
A) T'weren't invented here
B) We already made .30 caliber 150gr bullets, so why pick anything else?