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Hornady has introduced a new 6mm product, the "6mm Advanced Rifle Cartridge" -- https://www.thefirearmblog.com/blog/2020/06/03/hornady-announces-6mm-arc/
They are marketing it for military use, but as far as I've heard nobody's picked it up yet.
At first I thought 6mm ARC just the 6mm AR put into production (Grendel necked down to 6mm), but the cartridge dimensions are all 1% to 2% smaller than the Grendel, with a slight body taper where the Grendel has none.
ARC dimensions from http://ciar.org/h/6mm-ARC-Saami-Specifications.pdf
This cartridge looks mostly good to me, but the bullets they're putting in it are too heavy. It's not fast enough, with the given bullet compositions, to fragment well in tissue, even at short range. They are trading off terminal effect for long-range ballistics.
Perhaps something in 85gr or 90gr will become available someday. 87gr was the optimum calculated weight for 6mm AR, assuming bullet shape with a good BC -- any heavier and it drops below fragmentation threshold sooner because it's slower at the muzzle, and any lighter and it drops below fragmentation threshold sooner because it loses velocity faster.
It's at least interesting, and worth keeping an eye on.
They are marketing it for military use, but as far as I've heard nobody's picked it up yet.
At first I thought 6mm ARC just the 6mm AR put into production (Grendel necked down to 6mm), but the cartridge dimensions are all 1% to 2% smaller than the Grendel, with a slight body taper where the Grendel has none.


ARC dimensions from http://ciar.org/h/6mm-ARC-Saami-Specifications.pdf
This cartridge looks mostly good to me, but the bullets they're putting in it are too heavy. It's not fast enough, with the given bullet compositions, to fragment well in tissue, even at short range. They are trading off terminal effect for long-range ballistics.
Perhaps something in 85gr or 90gr will become available someday. 87gr was the optimum calculated weight for 6mm AR, assuming bullet shape with a good BC -- any heavier and it drops below fragmentation threshold sooner because it's slower at the muzzle, and any lighter and it drops below fragmentation threshold sooner because it loses velocity faster.
It's at least interesting, and worth keeping an eye on.