6mm ARC: Has Hornady Struck Gold?

**pinzgauer** · 11-16-20, 13:11

Originally Posted by Disciple

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.

Well if they've screwed the E-landers up I'm going to be a sad puppy as all the ones I've got through 2019 work flawlessly.

I'll find out, I've got two not even out of the wrapper, fresh production.

**mig1nc** · 11-16-20, 14:53

Originally Posted by pinzgauer

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.

Yeah, it's an interesting balancing act.

One challenge that is common to both competition and combat shooters is the need for rapid follow up shots and while having a ballistically capable cartridge. Hog hunters have a similar need, but it's a different dynamic. Plus the requirement for carrying enough to sustain a fight.

When you look at the NGSW guns they all seem to have some kind of novel approach to recoil mitigation. For example the ones that had a modified hybrid short recoil action combined with a short stroke piston.

I haven't personally found anything objectionably bad in an AR platform, but then again I've never shot those ridiculous large calibers like 50, 458, etc

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**pinzgauer** · 11-16-20, 15:02

Grendel definitely has more recoil than 556, though nowhere anywhere near 762X51 levels even in heavy AR-10s and battle rifles.

But it's not anywhere near the point that I feel it impacts follow-up shot speed.

I think it's kind of immaterial... I'm pretty confident you will never see big army replace 556 if the answer is reduced combat load for the same overall weight. Much less reduced combat load for heavier weight.

All my serving friends and relatives say exactly the same thing. Doesn't solve a problem they have.

I do think the periodic experimental programs are important to continue to advance the state of the art, but it's really hard to change physics. Unless we get a breakthrough with caseless or polymer case anyway.

I think there is optimization that could be done with timing of the recoil pulse and the operating mechanisms. And also trickery with powder pressure curves. (Leverevolution type stuff)

I could see a SAW upgrade to an intermediate cartridge since most of the supply chain is separate from the rifles. As much as I like the idea of it taking magazines and having commonality with carbines and rifles.

I've not looked into the case taper, can 6 mm AR use the regular links?

**Disciple** · 11-16-20, 15:16

Originally Posted by pinzgauer

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

Wouldn't a somewhat larger bolt head and matching barrel extension be enough? Isn't there enough room in the upper receiver for this? I don't see why we need an AR-10 bolt and carrier to allow a bit more pressure on a 0.445" head.

**pinzgauer** · 11-16-20, 15:48

Originally Posted by Disciple

Wouldn't a somewhat larger bolt head and matching barrel extension be enough? Isn't there enough room in the upper receiver for this? I don't see why we need an AR-10 bolt and carrier to allow a bit more pressure on a 0.445" head.

I forget who it was but there was a company who made AR-15 compatible upper receivers that used a larger receiver extension and bolt head. Might have had to use their bolt carrier as well, I don't remember.

It's kind of immaterial for me because it's a very expensive change for not much increase in velocity. And strictly a hand loading proposition unless a government got behind it.

You also start running into case capacity issues which is why an intermediate frame is of interest. You can have a meatier receiver extension AND longer overall length.

Constructor knows all the details in math behind it, and he might have even sold some of the improved receiver extensions and bolts.

My interest was to get a little bit more lethality at range than with 5.56, especially with hunting bullets while maintaining a decent trajectory.

6AR, Grendel, and SPC are all compromises.

I think they're pretty good ones, and with the AR-10 world demystifying a bit to me you're not going to see much traction with an intermediate frame. It's pretty easy now to put together an AR-10 out of parts that just works first time. (And easier yet to buy a LMT, h&k, or KAC)

It's just too easy to jump to something like Creedmoor or 260.

**md66948** · 11-17-20, 05:38

Interesting 9 min. video.

https://www.youtube.com/watch?v=zw5RhARZYRs

**Tokarev** · 11-22-20, 18:39

Looks like a great predator eradication cartridge.

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**RUTGERS95** · 11-24-20, 10:00

Originally Posted by Alpha-17

I tend to be very skeptical about these "next big thing" rounds. I started buying guns at the point 6.8SPC and 6.5 Grendel were starting to get big and I remember all the hoopla about .300 BLK. Now the flavor of the month is 6.5 Creedmore For the most part, I don't see the point of these. If I want lightweight, 5.56 does it, if I want power, .308/7.62 NATO tickles my fancy.

right there........