FN 6x51


#1

I got this case today in a box full of various cases:

Headstamp is “(+) FN 63”. OAL is 51mm, inside neck diameter is approx 6mm. There looks to be marks on the neck from necking down. Apart from the neck being a bit short that case is identical to a .243 Win. Was this just someone forming 7.62x51 Cases into .243 for shooting or could this be some sort of experimental round (unlikely)? This is a fired case, but is Berdan primed, so someone either got these as NPE brass or pulled the 7.62 NATO bullets from them to resize them as .243 rounds.


#2

Labbett (Assault Rifle Ammunition - 5.56mm to 11mm calibre) describes an FN experimental 6.5 x51mm cartridge for the Swedish Army - hs is given as (+) FN 62. The bullet diameter is given as 6.8mm. This compares to 6.18mm for the 243. A photo of the 6.5x51 is shown in Jean Huon’s book on Military Rifle and Machine Gun Cartridges. Unfortunately, I have been unable to find exact measurements of the cartridge or whether (+) FN 63 cases exist.

Dave S


#3

Yes, FN even made up some FAL in 6.5x51mm for the Swedes to test. Rarer yet is the prototype FAL in 6.5x55mm made for previous Swedish testing.


#4

Thanks for your input. I will put this aside as a possible experimental round.