Q: I am puzzled by the designations of most European cartridges and have trouble interpreting them, particularly some of the 8mm rounds. Can you please help with an explanation?
Martin S Harland
A: The metric system is really quite simple. Metric cartridges are normally designated by two sets of figures. The first is the calibre and the second the case length, both in millimetres.
Thus the 7x64mm is a 7mm calibre with a 64mm case length.
An R indicates a rimmed case and its absence a rimless one. The name of the designer or manufacturer may be tacked on the end: Vierling, Suhler, Mauser, RWS, Brenneke etc.
A major source of confusion is the two slightly different 8mm calibres which came about as follows: The original German military cartridge had a .318” (8.077mm) diameter bullet when adopted in 1888. So did all the 8mm sporting cartridges developed around that time. However, in 1905 the cartridge was altered to use a .323” (8.204mm) diameter bullet, and shortly thereafter 8mm sporting cartridges all followed suit.
The original German military cartridge is indicated by a J (for Infanterie, the German I and J being interchangeable), and the newer one by an S. For example, the 8x57J has a .318” bullet and the 8x57JS the .323” bullet.
Incidentally, the metric designation for the .30-06 is 7.62x63mm; the .308 is a 7.62x51mm and the .223 Rem is a 5.56x45mm.
Hope this satisfies your curiosity.
The .223 Rem is 5.56 x 45mm. A bit of a typo shown above.
Thanks for the correction, Richard! For those who missed it, we had the .223 equivalent as 5.56x54mm. Makes you wonder, though – a 5.56×54 wouldn’t be too far removed from the old .303-22. There have been some 54mm cartridges produced, notably the Russian 7.62x54R, and surely someone must have made a wildcat in .22 calibre.