Good Monday Evening! I have been fairly busy working on a few things, but felt I needed to try and get an update out there since SAAMI accepted a few new cartridges. This happens every 6 months as that is the frequency that the SAAMI committee meets. This most recent meeting happened at the 2022 SHOT Show.
These are all rifle cartridges and I will be updating the Rifle Cartridge’s Catalog to include these new chambers.
6mm GT
This cartridge was introduced by Hornady. Think of it as a between cartridge. Not quite as big as the 6mm Creedmoor, 243 Win, and not quite as small as the 6mm BR or the 6XC. As with most cartridges, this has been a wildcat for some time and has gained some popularity with those shooting PRS.
The goal of this cartridge is to try and mimic the low standard deviation that is offered by 6BR but still gets gain on some of the velocity you can achieve with the 6mm Creedmoor. As many have found out, 6mm is kind of a sweet spot as it combines low recoil with high BC.
6.8 True Velocity Composite (6.8TVC)
This is probably the most interesting cartridge in the SAAMI catalog. It is the first cartridge that is based entirely on polymer case technology. You will note there is no external case neck. The case stops at the shoulder.
The big advantage of polymer cases is weight. Brass is dense and replacing it with steel or aluminum nearly always results in a dramatically lighter case. However, nothing is quite as dramatic as replacing it with a polymer case. This is not a new technology, after all, we have been using polymer for shotgun shells for some time. To see it used with rifle and at service pressures of 65kpsi, is a relatively new thing.
The 6.8TVC is aimed at LEO and Military contracts as a polymer case that can increase the number of rounds a soldier can carry. There has long been a push to increase the caliber from 5.56 to something larger, and the 6.8 caliber has been bounced around a few times.
I have previously been critical of the polymer cases as I have been concerned about what happens when a polymer case gets left in the chamber. As it was pointed out to me that polymer does not conduct as much heat into the chamber, and the chambers do not get as hot as fast. I have also been reassured it is not an issue. With several militaries evaluating the technology globally, it will be interesting to see how quickly this gets adopted.
A few other things of note is the cost of polymer is substantially lower than that of brass. For those looking to pinch pennies and still shoot; polymer may be the way to go. TVC also claims that neck tension is far more consistent with their ammunition than what is achievable with brass, resulting in more consistent and accurate ammunition. All things to consider, but still I think I will be slow to make this transition.
338 Weatherby Rebated Precision Magnum (338 WBY RPM)
For those looking for a new magnum cartridge, Weatherby has a new 338 Magnum. The rebated rim allows it to be used on a rifle with a .473in bolt face. For comparison that is basically any 30-06 or 308 Win family cartridge. This cartridge is more or less a necking up of the 6.5 Weatherby Rebated Precision Magnum.
I suppose the purpose of these cartridges is to have a “Magnum” chambering in your caliber of choice while also having an ultra-light rifle. I do not see anything in these cartridges that would make them better choices for long-range targets or hunting when compared with what we already have.
If you are someone who hunts a lot and would like to save some weight on your pack gun, I suppose this might be something to look into. However, I am not sure the performance or the potential weight savings is going to justify the cost of a new rifle. That’s just me, someone else who is a bit more “High Speed, Low Drag” may disagree.
That is the new SAAMI cartridges for this meeting. I suspect next meeting we will see the 30 Super Carry on the list given Federal and Smith & Wesson are in current production. The jury is still out on that new cartridge. I have a few of your looking for versions of the Powder Burn Rate Chart. I am in the process of updating it and will send it out when completed. It takes time to hear back from companies on their powders and then takes a bit of time to do some research to place the powders in relative order. It will be a little bit longer before I publish the updated version. Thanks for being patient.
As always if you are looking to get in touch, the best way is to send me an email at jay@theballisticassistant.com. You may check us out on Parler, Facebook, Instagram, and Reddit. If you’d like to submit a load to our load database, the instructions are here.
As always, shoot straight and stay safe!
The Ballistic Assistant