All modern 8mm rifles, including all German military arms manufactured since 1905, use .323 inch diameter bullets. However, German military rifles manufactured between 1888 and 1905 used a .318 inch diameter bullet. Many of those rifles were rebarreled to .323 inch bores after 1905, but some rifles of the smaller bore size were brought back from WWI and WWII and still exist. Some German sporting guns, particularly combination guns made until 1938, used 8mm cartridges with .318 inch diameter bullets. Sometimes, a .323 inch diameter bullet can be loaded and fired in a cartridge intended for a .318 inch groove diameter, but dangerously high chamber pressures result. If you do not know that your bore size is .323 inch, slug your barrel before loading .323 inch diameter bullets. There are two Pro-Hunter bullets in .323 inch caliber in Sierra's line and both are the Spitzer type.
These 8mm hunting bullets model 2410, provide exceptional accuracy together with deep penetration and reliable expansion on medium and heavier game. The 175 grain #2410 gives the 8x57mm shooter an excellent big game bullet and is suitable for 8mm magnum cartridges.