Old School
If you grew up in the ’60s and ’70s, you were likely to run into a .243 Winchester on a typical deer hunt. A derivative of the .308 Winchester, the .243 has always been a popular low-recoiling hunting cartridge.
Launched about the same time by a competitor, the 6mm Remington was a less popular but comparable option. Both cartridges have stood the test of time, pushing their typical 70 to 100-grain bullet quite fast, making them great for varmint hunting and smaller big game animals.
The characteristics of these cartridges often led to them being relegated to either a “ladies' caliber” or something for new shooters. There is nothing wrong with that, but they shouldn’t be looked at as lesser chamberings. I would happily take a .243 on a deer hunt or something comparable; the lightning speed and flat trajectory would come in handy.
Way back, you could have purchased a Model 70 chambered in .243. These days, there are rifles from nearly every manufacturer chambered in the cartridge, whether you want a bolt-action rifle from Savage or Sako or even a lever-action .243 from Henry.
Modern Performers
If the .243 Winchester was so good and is still a popular chambering in today's firearms, you might ask, “Why fix what isn’t broken?” Hornady released the 6mm Creedmoor nearly 10 years ago, and much to the horror of the Creedmoor haters, it took off. With a supply of high-quality components, it made sense.
What did the 6 Creedmoor have that the .243 didn’t already cover? Modern performance is the answer. Creedmoors came with aggressive twist rates like 1:8 and 1:7.5. The .243 has a slower twist rate, which limits its ability to stabilize many modern bullets larger than 100 grains. The faster twist allowed the 6 Creedmoor to push bigger bullets like 108s and 115s at fantastic speeds, giving it a huge ballistic advantage.
The 6mm GT is one of my favorite 6mm cartridges. Following the success of cartridges like the 6mm Creedmoor and competition cartridges like the 6 Dasher and 6 XC, the 6mm GT was released by GA precision and produced by Hornady. In a happy medium of performance and longevity, the 6 GT fits easily into AICS magazines like the others I just mentioned, while giving excellent ballistic performance and better barrel life than larger cartridges.
All these modern performers are shorter cartridges than the older .243 Winchester, allowing them to load longer, higher ballistic coefficient bullets and feed from magazines. Plus, the smaller powder charges aren't as quick to erode the chamber throat, which degrades accuracy.
Modern Sporting Rifles
Any of these cartridges could be and frequently are chambered for semi-automatic rifles like the popular AR pattern. I would be remiss if I didn’t mention the popular 6mm ARC, as it is the most likely to fit into this category – mainly because it fits in a 5.56-sized action and magazine. The 6 ARC offers 6mm attributes like ballistic performance and heavier bullets but still fits into an average AR-15 rifle.
Additionally, due to its smaller size, it burns far less powder, extending the life of the barrel. This makes even more sense in a semi-auto, as they tend to shoot much higher round counts than typical bolt-action rifles. Guns.com offers a wide variety of 6 ARC autoloading rifles, like the CMMG Resolute series of rifles.
The 6 ARC can obviously be used in bolt-action rifles as well, and it does an excellent job. The round is typically given a 1:7.5 twist, which helps it handle modern bullet selections. I am a bit partial to the Howa Mini, which I have used with great success, but there are also great bolt-action options from Ruger and Savage Arms. With the cartridge gaining popularity every day, you are likely to find six of one and half a dozen of another.
6mm Applications
All these 6mm cartridges can be an optimum fit for various purposes. If I were looking for a 6mm big game rifle, I would likely choose the .243 Winchester. It offers maximum velocity and isn’t likely to be shot as much, but I would likely pick a faster twist than the typical .243 to take advantage of the better bullets available today.
If my goal were competitive shooting, I would select the 6mm GT. It gives exceptional performance without giving up efficiency and runs flawlessly from AICS magazines, which are the standard for competitors, even when loaded with long, high ballistic coefficient bullets. Some of the same could be said for the 6 Creedmoor, albeit with perhaps less efficiency and durability.
The 6mm ARC has also worked out well for a low-recoiling hunting rifle. I probably shoot my various 6 ARC rifles more than all the others. You guessed it: that’s because it is cheap and very effective. Whether from a semi-auto carbine or from a bolt-action rifle, the ARC has served us well for long-range plinking and for putting venison on the table.
Six Ways to Sunday
You can see how any of these 6mm cartridges could easily fit into your rifle collection. They can certainly spice up your shooting taste, too. You might be thinking, “Why would I want this 6mm over my 5.56 or 6.5 that might already be covering that base?”
Don’t think too hard about it. We often need an excuse to get another rifle, and the flat-shooting family of 6mm cartridges could be all the reason you need. With any luck, I hope you have learned enough to help you decide on your next favorite rifle. Balance the effects of barrel twist and case capacity for a light-recoiling rifle that is a joy to shoot. Whether you choose a .243 or Hornady’s ARC, it’s 6s either way.
