New Hornady 6mm ARC cartridge

[jellydonut]

The mention of the slice of DoD adopting makes me crazy when they're going to this new 6.8. Crazy only in that I'd want to invest in a non 5.56 upper for a caliber with legs of longevity. This 6mm ARC sounds more appealing to me than the rest.

The new 6.8 is a (ultra high velocity) short action cartridge, this one can complement it rather than compete with it.

[JHC]

The new 6.8 is a (ultra high velocity) short action cartridge, this one can complement it rather than compete with it.

Oh duhhhhh, the new 6.8 can't fit existing lowers. My bad. I get it. Thank you.

[OlongJohnson]

Some discussion over on 6.8Forums has been ongoing for awhile.

https://www.68forums.com/threads/6mm-arc.133947/

And the barrel H discusses making:

https://ar15performance.com/inc/sdetail/38016/64703

[ranger]

I go down this path regularly - 6.8 SPC, 6.5 Grendel, 224 Valkyrie, plus 223 uppers for ARs. There are multiple 6mm wildcats for ARs including 6mm Grendel based.

Hornady seems to be all in on this cartridge and key is the selection of high BC projectiles for hunting and target from the start. 6mm is dominating PRS events.

I will probably build a 6mm ARC upper with a 22 or 24 inch barrel for long range work. I will watch for bolt actions with 26 inch barrels in 6 ARC to compete with 6mm BR and 6 Dasher with much cheaper brass and no case forming.

I will bet on success for the 6mm ARC and it may hurt the 224 Valkyrie. I would expect hunters to stick with 6.8 or 6.5 Grendel

[RAM Engineer]

The e-Lander 6.5 Grendel mags from AA are very high quality. Much more robust than any metal 5.56 AR mag I’ve tried, with the exception of HK.

Have you tried the PRI mags?

[Clusterfrack]

Have you tried the PRI mags?

Nope. Figured that AA is the place for Grendel stuff, and haven’t been sorry.

[Clusterfrack]

How about a 12.5?

6.5 Grendel does really well in an SBR. I don’t see velocity values as a function of barrel length for the 6 ARC, but I’m guessing it’s loses more than the 6.5 per inch.

[SecondsCount]

I'm a huge 6mm fan so this should make things interesting. When the 22 Nosler came out, I wanted push back the shoulder and neck it up to 6mm so it would fit in an AR mag with a long high BC bullet.

I think I still prefer the 6.5 Grendel. More energy, and as far as I can tell better performance out of a 16” barrel.

In a short barrel, the 6.5G might win, but comparing the 123ELD 6.5G Hornady load against the 108ELD 6ARC load, at 500 yards the 6ARC wins. Less drop and more energy, less wind drift. Hornady shows a 24" barrel for both tests.

[ranger]

Seems like the DOD agency wanted an 18 inch barrel for a SPR like role? There are a few threads where some of the early builders cut some barrels back inch by inch to 12 inches or so. Seems Barret shipped some 6mm ARC rifles to DOD.

https://news.barrett.net/2020/06/03/...les-to-us-dod/

[littlejerry]

This cartridge is interesting. 6.5g never did it for me because it didn't add an appreciable amount to the max range vs good 5.56 loads, maybe 100 yds extra before transonic. With cheap 5.56 77 OTM on the shelves it makes it a tough sell for marginal gains.

224 Valk definitely had gains on paper, but lots of dissatisfied customers with real world accuracy. It was also still a 224 projectile so not legal for hunting in some areas.

This 6MM could be Goldilocks for a competition cartridge in small frame ARs that reaches 1k yards but can also do work as a smedium game round.

I'm not an early adopter, so ill keep shooting my 5.56 in DMR matches and cursing the wind for now. But I could see buying an upper next year if Hornady does a good job with it.

Lantac Published some data on 18 and 14.5 barrels here:
https://soldiersystems.net/2020/06/0...dicated-e-bcg/

Even if you assume this is "optimistic" and those velocities are more representative of 16" and 20" barrels, the numbers look good.