.243 Winchester- The forgotten 6mm cartridge

My experience with the .243 cartridge for use as a Long Range Highpower cartridge dates back about 10 years or so. After building a .300 WSM, I realized that the recoil was hurting the quality of my shots. The WSM shot great, but I couldn’t always execute good shots when shooting it. From here I built a 6.5-284, and it shot well. I also had a very accurate 6 BR at the time, and my logic in going to the .243 was to get wind performance equal to the 6.5-284 with recoil similar to the 6 BR. The experiment has worked out well indeed!

For a load, currently I’m shooting Lapua brass, PMC (Russian, similar to Wolf) primers, VihtaVuori N160 powder, and Berger 105 grain Hybrid bullets. I switched to the Hybrid bullets fairly recently at the beginning of the 2015 season. Previously I shot the 105 Berger hunting VLDs, and in testing I found that the Hybrids were just as accurate without having to seat the bullet into the lands. The velocity of this combination when shot through the excellent Bartlein 5R barrels (32” length) is 3275 fps.

Further details of the load include the fact that the bullets are jumping from .035-.060”. I only use one seating depth for ammunition for multiple guns (I know some benchrest shooters will stop reading right here!) and the bullets jump further in the worn barrels than in the fresh barrels. The bullets are pointed up in our Bullet Pointing Die System and are moly coated. The moly does extend the cleaning interval a little bit, probably 20% or so. The brass is all neck turned to .0125” thickness.

My loading process is different than many people expect. I load my ammo on a Dillon 650. The powder charges are weighed, and of course I’m using our own Whidden Gunworks dies. The brass is full length sized every time, and I run one of our custom sized expanders in my sizer die. The expander measures .243” which yields the desired .001” neck tension. In my experience, the best way to get consistent neck tension is to run an expander in the case neck at some point. When sizing the case neck by a minimal amount such as is the case here, I don’t find any negative points in using an expander in the sizer die.

In my experience, the keys to accurate long range ammo are top quality bullets and the most consistent neck tension you can produce. From these starting points, the use of quality components and accurate powder measurement will finish out the magic.

Posted in Reloading.