6mm GT or 6GT, the New 6 on the Block.

by AJ | Last Updated: March 29, 2021

What is a 6mm GT

Launched sometime in January 2019 with official public acknowledgement by George in February 2019. The GT in 6mm GT, stands for George (as in George Gardner from GA Precision) and Tom (as in Tom Jacobs from Vapour Trail Bullets), the two guys who developed the cartridge, out of the need to have a 6mm cartridge that can use the forgiving propellants that the 6BR, 6BRX, 6BRA and 6mm Dasher use providing large nodes making load development easier for each new barrel, whilst still being able to feed from a magazine reliably like a 6mm Creedmoor. They also wanted it to be more forgiving on the barrel life, and still provide comparable high muzzle velocities with tight twists required to stabilize the long high-BC 6mm bullets.

Although starting as a joke on Sniper’s Hide, and the name sticking from then, the GT in 6mm GT does not stand for Gay Tiger, hahahaha. The 6mm GT quickly started taking off in the PRS and NRL match scene from 2019 onwards and has become a firm precision rifle cartridge favorite from a few custom precision rifle builders.

6mm GT Brass

Initially brass for the 6mm GT could be formed from 6.5×47 Lapua brass, but that was quite labor intesive with a full length sizing die and tons of case lube. Thankfully though, finding 6mm GT brass for sale, there are a few companies now including Hornady, ADG making 6mm GT brass cases, however the Hornady 6GT brass is only for sale available directly purchased through GA Precision.

6mm GT for Competition

Being born out of the need to improve both on both the 6mm Dasher variants, as well as the 6mm Creedmoor, and to only do so for competition and precision rifle match shooting purposes, means that the 6mm GT was born and bread for competitive rifle shooting. It excels at PRS and NRL style matches, and even works well for long range precision rifle matches.

6mm GT for Hunting

Being very close ballistically to the 6mm Creedmoor, the 6mm GT will absolutely work very well with CXP2 average sized animals like Deer, Pronghorn, Boar and Sheep, and of-course anything below even better. We have managed to take down more 12 white-tailed deer on one single weekend with a 6mm GT chambered rifle, all but one taking just one shot to kill. The deer that required two shots, was because of shooter error and not anything to do with the rifle or round.

For a dedicated hog or boar gun, the 6mm GT can also be chambered on a AR type semi-auto platform thanks to it’s reliable feeding characteristics. Couple that to a red dot sight, with a rifle mounted laser, and you have a high-speed hog killing machine, both close, and long range.

6mm GT Barrel Life

This varies depending on your rifle, barrel, load, velocity and bullet. There are many factors that determine the number of shots a barrel can take before the lands and rifling become worn to a point where the accuracy suffers. For the 6mm GT, using less powder than the 6mm Creedmoor and powders with a more forgiving burn rate means you will get more shots out of your barrel than with a 6mm Creedmoor, 6mm XC or 6mm Super LR.

6mm GT Load Data

Hodgdon H4350 and Varget seems to be the propellants that works the best in it. George Gardner admitted that the 6mm GT cartridge was specifically developed for and around Varget powder, but in some of our own load development and testing, H4350 provided even higher velocities with lower SD’s, but not by much, so we would gladly use either of them.

6mm GT Velocity

In our own testing, the 6mm GT has been shooting 107 grain Sierra Match King bullets with a muzzle velocity at around 3015 fps with 37.8 grains of H4350 and 105 grain Berger Hybrid bullets at around 3015 fps muzzle velocity with 34.2 grains of Varget powder.

6mm GT vs 6mm Creedmoor

The 6mm GT offer similar mag-fed reliability to the 6mm Creedmoor, with similar velocities, but with slightly less propellant, and is able to use the more forgiving propellants which make the 6mm GT slightly easier for load development with new barrels. The less propellant usage of the 6mm GT also means it is more forgiving to the barrel so offers an increase in barrel life compared to the 6mm Creedmoor.

6mm GT vs 6mm BR variants

Whilst some with custom setups argue, it is well known that there are some feed issues with the shorter 6mm BR variant cartridges like the 6mm BR, 6 BRX, 6 BRA and the 6mm Dasher, the longer case of the 6mm GT means it feeds as reliably from a magazone as a 6mm Creedmoor, and offers slightly higher powder capacity and in turn velocities than the 6mm BR variants, whilst still being able to use the same accurate and forgiving propellants.

Is the 6mm GT worth it?

Although slightly superior to the 6mm BR variants and the 6mm Creedmoor in some aspects, but is that enough, or does it amount to it being actually better or worth the extra cost to create, or even change to if you have one of the other already?

There haven’t been many concrete claims of getting more than 2000-2400 shots out of a barrel with the 6mm GT, with some arguing that if people did, they would be proclaiming it loudly, thus basically putting it into the same barrel life territory as the 6mm Creedmoor, which nullifies that advantage it has over the 6mm Creedmoor. So if you already have a 6mm Creedmoor, we would most certainly not recommend going through the whole process and added expense of having to buy new brass, dies and redoing all your load development to change over.

You will also find many competitive and average Joe’s shooting 6mm BR and 6mm Dashers with a primal rights or some other mag conversion kit, having very few if any mag-feed issues at all, so that pretty much also nullifies the need to move away from those calibers if you already own one of those or the reloading equipment for it.

The last benefit of the 6mm Creedmoor over the 6mm GT is the commercial availability of both brass and dies, this makes the 6mm Creedmoor cheaper, and easier to get access to.