6mm ARC: Has Hornady Struck Gold?

[pinzgauer]

My point about the CMMG thing is that the system should allow slightly larger cartridges to work at higher pressure than a hogged out AR15 bolt would allow. Not necessarily talking about anything specific to the Grendel or ARC. What I’d like to see it do would be to take something that looks like slightly larger AR mags, instead of AK mags, and launches something that looks like a slightly longer 6.5mm Grendel in the area of ~2.5” oal, and a max pressure of greater than 52,000 psi.

Something that looks like halfway ish between an AR15 with a ~5.5mm projectile and an AR10 with a ~7.5mm projectile. Because it would make for some interesting hunting and target rifles. Not for any tactical interest.

I know, its a little nutty and def off-topic.

I’m not knocking Grendel. I’m a convert, actually. And I might try the ARC in a couple years.

Makes perfect sense. Some kind of intermediate frame would be cool.

[Tokarev]

Ballistic Advantage shows 6MM ARC as an option on their website although no barrels are shown yet.



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[mig1nc]

Makes perfect sense. Some kind of intermediate frame would be cool.

Check this out, scroll down to see the AR-12 http://www.sadefensejournal.com/wp/t...assault-rifle/


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[pinzgauer]

Check this out, scroll down to see the AR-12 http://www.sadefensejournal.com/wp/t...assault-rifle/

Ah, the perpetual "Battle of Wanat our M4's melted and we were outranged" trope...

Note that I am a hardcore Grendel shooter, and appreciate the "reclaim the 400-600m" range mindset. And see similar attributes in the 6mm ARC.

But here's the deal. I'm also close to someone in the exact unit involved in the Battle of Wanat. He served under and with soldiers/leaders who were there. And their learnings/outcome was not that they needed a new rifle/M4 replacement. And certainly not a cartridge/platform that had 25-30% reduction in combat loading for same weight. They still remember and train to achieve a different outcome.

Literally, the news articles and even the link you shared were comparing M4's to PKM's and similar machine guns. Which is just silly, as if you are willing to carry a PKM, you could (and often do) have M240B's and similar.

Wanat also had plunging fire from high sites. As I read the accounts (there are multiple good ones), I was asking where are the Mortars? Where are Company & Battalion assets? Where's the CAS?

Which when I asked, he commented: "Funny you should mention that". Because those areas have been focus areas of maintaining expertise and capability. And specifically addressing some bad habits regarding usage of platoon assets. Bottom line: Asking for a carbine with 400-600m range with MG rates of fire is unrealistic if they are not trained well in 300m shooting. And doctrine has SAW's and mortars covering that range and out further. Which with proper training and eliminating bad habits is very lethal.

But much of the issue was ROE and operating practice. Fundamentally, Platoons were spread out of interlocking support capability. And beyond any Company support capability, much less BN assets.

And had restrictive ROE preventing usage of mortars against high site PKM/RPK emplacements using plunging fire. Which the locals had trained for since Soviet era, knew what worked, what did not. And knew US CAS response times, they had about 20 minutes to rain lead from above, then quietly slipped away. All issues beyond weapons capability, somewhat unique to A'stan and the leadership at the time.

And I'd really recommend reading the following to understand the mythos that leads to these debates:
"To Quell The Korengal", "The Chosen Few", "Outlaw Platoon". Give "Restrepo" a watch as well.

It will open your eyes, and make you question why we keep wandering into these types of situations. Who puts outposts at the bottom of a fishbowl? (Calling your name, COP Keating) Then tells Joes they can't use mortars to eliminate threats because it might kill some goats?

So as much as I'm a fan of getting as much capability from AR-15 frame's like with Grendel and ARC, I don't spend much time fantasizing about the mainstream Army replacing the M4 with a miracle cartridge or carbine.

[mig1nc]

Ah, the perpetual "Battle of Wanat our M4's melted and we were outranged" trope...

Note that I am a hardcore Grendel shooter, and appreciate the "reclaim the 400-600m" range mindset. And see similar attributes in the 6mm ARC.

But here's the deal. I'm also close to someone in the exact unit involved in the Battle of Wanat. He served under and with soldiers/leaders who were there. And their learnings/outcome was not that they needed a new rifle/M4 replacement. And certainly not a cartridge/platform that had 25-30% reduction in combat loading for same weight. They still remember and train to achieve a different outcome.

Literally, the news articles and even the link you shared were comparing M4's to PKM's and similar machine guns. Which is just silly, as if you are willing to carry a PKM, you could (and often do) have M240B's and similar.

Wanat also had plunging fire from high sites. As I read the accounts (there are multiple good ones), I was asking where are the Mortars? Where are Company & Battalion assets? Where's the CAS?

Which when I asked, he commented: "Funny you should mention that". Because those areas have been focus areas of maintaining expertise and capability. And specifically addressing some bad habits regarding usage of platoon assets. Bottom line: Asking for a carbine with 400-600m range with MG rates of fire is unrealistic if they are not trained well in 300m shooting. And doctrine has SAW's and mortars covering that range and out further. Which with proper training and eliminating bad habits is very lethal.

But much of the issue was ROE and operating practice. Fundamentally, Platoons were spread out of interlocking support capability. And beyond any Company support capability, much less BN assets.

And had restrictive ROE preventing usage of mortars against high site PKM/RPK emplacements using plunging fire. Which the locals had trained for since Soviet era, knew what worked, what did not. And knew US CAS response times, they had about 20 minutes to rain lead from above, then quietly slipped away. All issues beyond weapons capability, somewhat unique to A'stan and the leadership at the time.

And I'd really recommend reading the following to understand the mythos that leads to these debates:
"To Quell The Korengal", "The Chosen Few", "Outlaw Platoon". Give "Restrepo" a watch as well.

It will open your eyes, and make you question why we keep wandering into these types of situations. Who puts outposts at the bottom of a fishbowl? (Calling your name, COP Keating) Then tells Joes they can't use mortars to eliminate threats because it might kill some goats?

So as much as I'm a fan of getting as much capability from AR-15 frame's like with Grendel and ARC, I don't spend much time fantasizing about the mainstream Army replacing the M4 with a miracle cartridge or carbine.

Dude, I was just linking to the picture of a midsize AR receiver like that being discussed. I'm not driving into the issues with that particular incident.


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[pinzgauer]

Dude, I was just linking to the picture of a midsize AR receiver like that being discussed. I'm not driving into the issues with that particular incident.

Dude, wonder if you posted the right link? As the one I read (end to end) was from 2015 had several pages of "we are overmatched", etc. Even 2/3rsd in it was still all "These enemy gunners rain .30 caliber projectiles from 800 meters and beyond"

And the rest was about cartridges to deal with 7.62x54 defilade threats, etc.

So I did not see a picture of a mid-sized AR receiver. Maybe the wrong link? Or I'm missing it?

[pointblank4445]

...seems to be a good point to ask this question.

Recently heard from a precision/scoped carbine instructor that gets to see some Grendels in his classes from time to time that it's common that if they are run fast that they experience extraction and feeding failures with relative consistency. While most if not all are probably home-assembled guns where tolerance stacking and the less-refined formula may be a factor, might this trickle down to the 6ARC if in fact this is exacerbated by bolt face geometry, case design, magazine geometry of attempting the shoe-horn the .220 Russian parent case into the 5.56/.223 platform?

While I understand this is not the original intent, the whole point of keeping in a small-frame AR15 is versatility and that would lend itself to a faster cadence of fire in a defensive or suppressive context.

Discuss...

[Disciple]

Dude, wonder if you posted the right link? As the one I read (end to end) was from 2015 had several pages of "we are overmatched", etc. Even 2/3rsd in it was still all "These enemy gunners rain .30 caliber projectiles from 800 meters and beyond"

And the rest was about cartridges to deal with 7.62x54 defilade threats, etc.

So I did not see a picture of a mid-sized AR receiver. Maybe the wrong link? Or I'm missing it?

I am glad you wrote your long reply as I found it quite interesting, but I think this is all he was referencing:

]

Top to bottom: Similarly equipped 7.62mm NATO caliber AR-10 Rifle (9.6 lbs.), 264 USA caliber AR-12 Rifle (7.2 lbs.) and 5.56mm NATO M4 Carbine (6.2 lbs.). The intermediate 264 USA caliber rifle weighs close to the M4 Carbine yet outperforms the 7.62mm NATO AR-10 weighing 2.4 pounds more.

[Disciple]

Recently heard from a precision/scoped carbine instructor that gets to see some Grendels in his classes from time to time that it's common that if they are run fast that they experience extraction and feeding failures with relative consistency.

Magazines are a problem. I have a few of the new E-Lander ones that are supposed to be the best and I cannot make them feed. I have some old magazines that seem to work fine. If I only had the E-Lander magazines I would get rid of my 6.5 Grendel.

I don't see a reason for extraction problems to be linked to the cartridge itself. I would first suspect off-brand bolts with inappropriate extractor springs or poor quality extractors, or poorly executed gas systems. I would think the more robust case rim would help extraction, all else being equal.

[pinzgauer]

I am glad you wrote your long reply as I found it quite interesting, but I think this is all he was referencing:

]

I see it, I see it. So I glossed right over that one picture cuz I was mistakenly misremembering the 264 USA was just one of the AMU's intermediate cartridge experiments in the AR-15 magwell length.

So for the record I stand corrected, there was an intermediate frame AR in that very long article.

It is Grendel / 7.62x39 based, but it's stretched and has a much longer cartridge length. So that must be one of the intermediate platforms or a small frame 308, hard to tell from the pictures. (POF Revolution?)

If you were starting with new carbines that would probably be an optimal size.

Even just seating Grendel bullets longer than AR-15 mag length in bolt guns gives noticeable gains, and stretching coal to 2.6 in would be getting into that optimal range. Both AMU, Bill Alexander, and others have long felt just a little bit more case capacity would be ideal.

But you immediately start exceeding AR-15 bolt thrust capabilities, so you're jumping to bigger bolts and most compatibility with the AR-15 platform evaporates

The magic of Grendel and ARC is in maximizing the capabilities of the widely available AR-15 platform, including things like bolt thrust limits. That was my initial interest in Grendel and I think also the attraction of ARC.

If you jump beyond that and are approaching AR-10 weights, it's just too easy to jump to creedmoor or 260 which is what I think we're seeing people do.

As to the never ending magazine reliability issue thing, I've expressed my opinion and experiences. I've never seen an issue across multiple grendels, nor is it common in the Grendel forums outside of what I shared previously: The group of people who are trying to make a better Grendel by dinking with the Sammi chamber/ throat / bolt dimensions. That and some improperly reamed throats from a manufacturer that should have known better and screwed a bunch of people.

I've mostly used Alexander-Arm's bolts and barrels and just never seen an issue.

But I have $79 tool craft BCGs that have been flawless, and I know of multiple D-Star bolts from 2007-2008 that are still working with regular shooting.

So I personally don't buy cheap bolt issues. It is certainly possible to over pressure them. We regularly read about people talking about fully flattened primers in Grendel, which is way above safe bolt thrust limits due to the PSI required to flatten a primer.

It's mostly reloaders new to semi-auto reloading and not paying attention to bullet seating depth.

But personally I'm convinced that the Grendel reliability issues you hear about are people/smiths trying to make a product improved Grendel and not using production stuff.

It's very simple things like tighter necks. Huge arguments over that but the reality is that with millions of rounds tested, Bill Alexander found that tighter necks had almost no detectable improvement in accuracy, yet significantly increased reliability problems. So it was not worth it. "If a tighter neck significantly improved accuracy I would have done it in a heartbeat. It didn't. "(I personally discussed this with Bill Alexander once.)

I believe the AMU found similar.

Same for some of the throat optimization designs.

I've not heard of any negative experiences with the E-Landers. Have a couple of recent production mags to try so maybe I'll be disappointed. But I suspect not. And I shoot a bunch of steel case Grendel and reloads. (I've literally worn out Grendel and IMI 7.62x39 Grendel fireform brass by reloading it 10-12 times). Especially when you could get the nosler 123 grain CCU bullets as blems by the thousand count cheap.

If SOC units are really using 6 mm ARC, they're getting workable magazines from somewhere.