Reloading

6x45mm

Published: 2026-10-23

What is it?

The 6x45mm is a wildcat cartridge created by necking up the standard .223 Remington / 5.56x45mm case to accept 6 mm (.243") diameter bullets. While never standardized by SAAMI in the United States, it was officially standardized in Europe by the CIP as the 6 x 45.

History

The cartridge originated around 1965, shortly after the commercial introduction of the .223 Remington and the U.S. military adoption of the 5.56x45mm cartridge. Benchrest shooters and hunters sought to enhance the ballistic efficiency and terminal performance of the compact .223 case by loading heavier 6 mm projectiles. It became popular during the late 1960s and 1970s, particularly in benchrest shooting, because it has mild recoil, low powder consumption, extended barrel life, and accuracy.

Handloading

Any reloading data is purely for entertainment purposes. I don’t advocate that anyone should use my load data.

There is a lot of advice, guidance, techniques, and ideas on the internet on how to develop the best handload for a rifle. It’s pretty easy to fall into the rabbit hole of load development &nash; what works best for a F-Class shooter might not be the best process for someone who needs ammo for hunting. Personally, I’m finding that Justin Reeve’s Data Driven Reloading course might be a good place for a beginner to start.

Reforming brass for the Mauser 98k

The 8mm Mauser (7.92x57mm) round, in it’s current incarnation, has been around since 1903. It is a improvement of the original 7.92x57mm cartridge that was developed in 1888 by Peter Paul Mauser. Arguably, 8mm Mauser has been one of the world’s most popular cartridges, having seen significant military and civilian use over the past 100+ year. It also influenced the design of many of today’s cartridges, such as .30-06.

Finding good 8mm Mauser ammunition (in Canada at least) is becoming harder. The glut of military surplus rifles and ammunition for this cartridge is long over, and there are more modern cartridges which have gained a significant following.