This^!!!

Please don't take my following post to be argumentative. I am simply stating my perspective on the steel cased ammo subject.

I am a firearms retailer. I sell lots of Grendel uppers, bolts, extractors, magazines, barrels, and ammo. I own two Grendels and my wife, who I work with, owns two Grendels.

I sold a Diamondback Grendel this morning. The guy bought 4 boxes of Wolf steel cased ammo with it.

Later I sold some parts to build a Grendel to a guy today. We wanted to build one because he shot a Grendel that was purchased part-by-part at my store. He said he shot the guy's gun using steel case ammo and three shots at 101 yards could be covered by a quarter. I don't know if that is true and don't care enough to call him on it, the fact is he was satisfied with the performance of the steel cased ammo. He was so excited he came in and bought parts to build one for himself.

About 5PM I had a guy come over from Texas because he broke his BCA 6.5 Grendel extractor and we keep Alexander Arms extractors in stock. He told me he was shooting steel case ammo when the extractor broke. I don't believe the problem was so much the ammo as it appears BCA cuts a 5.56 extractor (thus removing the heat treating) to make their Grendel extractor. I have replaced 5 this year and had a talk with a rep at SHOT Show 2020 about the issue. I have yet to have an AA extractor fail.

I had a customer come in at 6:04 PM today and dropped off what he told me is a Criterion 6.5 Grendel barrel. It says KR Precision Firearms on it. He will be shooting Wolf steel case through it. I recently built four 10.5" Grendels for his hog hunting crew. He wasn't satisfied with the accuracy of his 10.5" Bear Creek Barrel so he ordered a Criterion. Meanwhile the rest of the crew are mowing down hogs with their builds. Last week one of the guys picked up four cases (2,000 rounds) of Wolf steel cased Grendel. I think that is seven cases total he has purchased from me. He has not purchased one single box of brass cased ammo from me.

These three examples are from today alone.

I own an Alexander arms barreled Grendel. I have shot less that two boxes of Hornady 123 A-Max cartridges through it. It put 9 shots of AMax in less that one inch. I put 7 rounds of Wolf in around 3.07". I have also shot over 1,000 rounds of steel case ammo through it. It bangs IPSC steel at 500 yards so easily the gun is boring.

What is my point? Lots of "regular Joes" are shooting steel cased ammo through a gun whose cartridge was designed to be accurate and put more energy down range that 5.56 NATO. Will the lack of steel cased ammo kill the 6mm ARC? I bet it would be not. However, the availability of steel cased ammo can catapult a cartridge in terms if public popularity.

I will be looking forward to selling 6mm ARC parts, guns, ammo, etc in my shop. I have already backordered lots of parts including reloading supplies and ammo.

Again, please don't take my post as being argumentative. I am simply stating what I see in an AR centric gun shop.

The invoice was in the box. It says he got a 10.5" Krieger Grendel barrel.

I remember talking with Bill when he was still going back and forth working out the details with Barnaul on getting the steel case right.

He saw it as a huge lever for making the cartridge more popular and to expand its place in the market for all the reasons you mention.

Sounds like you’ve got clientele that have more money than common sense.

Did you mention to him that his Krieger may shoot just as bad as the BCA with that shit ammo? A quality barrel needs quality ammo to perform to its potential. You could have a barrel capable of half-Moa, but if you feed it 3moa ammo, you’ve got a 2-3moa combo.

He’d of been better off with a mid grade barrel and mid grade ammo than trying to get that combo to work.

The 6ARC came to fruition as a precision long range round that could also be used for close engagements if needed. The people that are excited about this round likely aren’t happy with hitting ipsc plates at 500yds, they are going to want to hit much smaller targets, and they aren’t going to be upset if there is no wolf steel cased ammo, as they wouldn’t be putting that crap in a precision build in the first place.

I am call it with you ringing steel at 500 "so easily the gun is boring" because with your 3 MOA steel cased ammo gives you a 15 MOA variance at 500 yards.  How big is the steel, car door?  You may get hits, but not easily.

IPSC steels are about 15x25 (going from memory). It is basically a torso shaped silhouette.

Looking at the math, a 3 MOA gun/ammo system can "easily" connect with a 3MOA target (which a 15" target would be at 500). As in, if you hold the gun still while you squeeze the trigger, you will easily hit the target.

Looking further into the numbers,  we won't get a  "15MOA variance" at 500 yards. It should give us ~15" group size at 500 yards, which is still 3MOA. A 15" group can easily hit a 15x25 IPSC target.

ETA: easily hitting the target assumes the scope is dialed in with the proper hold for elevation. Where I shoot wind is not much of a concern at 500.

Not really. Most of my customers are in the Bear Creek price range. I can easily sell a $99 barrel or a $289 complete upper when there is $6.99 ammo to be had.


We will probably see $99 6mm ARC barrels and $289 6mm ARC uppers in the not so distant future (fingers crossed) and they will be easier to sell with steel cased ammo option than without.

I don't think you're being argumentative, I just don't think the folks and uses you're talking about are really the target market for the ARC (whether they wind up buying one or not). Where the ARC will really stand out is as a long range target round that fits in an AR-15, think PRS gas gun type uses. I don't think a cartridge has to be everything to everyone for it to be useful or commercially viable.

For the uses you're talking about, close range hunting and close to mid-range steel banging on large targets with low wind, the Grendel works well enough that I don't see why a lot of your customers would switch, especially if they care about steel cased ammo availability. I don't anticipate getting rid of my hunting Grendel, but for the kind of steel shooting I like to do, which starts at ~400 yards in a place where moderate to heavy winds are a given, the ARC will be a nice step up from the Grendel, or really any standardized AR round. I've never seen anyone shooting steel cased ammo at our local long range, but I'm certain I'll start seeing some 6mm ARCs there as soon as good barrels become available.

never mind, not pertinent.

If anyone has a 6mm ARC Cartridge, could you throw it on a scale to see how much it weighs?

Based on 6.5 Grendel 123gr weight of 17.8g, my weight estimate for the 108gr ARC is 16.83g, but it would be nice to have the exact weight.

Meanwhile, a 24rd E-Lander steel mag is 7.6 oz.

So current estimate is 1.37lbs for a loaded 24rd 6mm ARC mag.

I have been quite curious about this new fangled 6mm arc (hahaa it's just a standardized wildcat sold to military and then turned into a profitable market share for civilians) and it seems awesome on paper, and in practicality

I then looked into other rounds, based on 6.8 cases, and at same length, it seems to be able to hold more capacity of a powder charge, meaning even better results.  One round that comes to mind is the 6x6.8 or the 6mm DTI.  

6mm arc and 6.5 Grendel are about 35ish grains.  A 6mm dti is mid 35 to about 38


One other thing that comes to mind, is a cartridge manufacturer trying to get their slice of military market.  Sig is turning and burning on products that use the 6.8 case, bcg, etc.  Dig it!  
But Hornady comes in with a descendant of an AK case not already adopted by the military for use. The armorer's will have a logistical nightmare on their hands here in a few years when productions are up and parts start breaking.  The maintenance, and military budgeting systems, both come to my mind, being an 18+ yr Navy guy who fixes things for a living. I have become.bordrline violent with my supply guys before because I had to wait 3 months on basic air filters, but they were buying up automatic staplers to "keep our budget high". I digress.

I think I would have went with a 6mm DTI in the log run. Slightly more charge, works with already implemented mags and bcgs for the 6.8 platform ou there, in use since the early 2000s.  

I'm not a cartridge manufacturer with a large user base to potentially sway decisions though.  

I'm not bashing it, believe me. It looks like what the 224 Valkyrie should have been. When the 224 came, I wondered if it would have been better off in a 6.5 or 6mm design.

Thoughts?

6mm DTI can't handle long bullets, the case is too long. There's a reason Hornady (and other wildcats) are using the shorter/fatter case. If you want to shoot the lighter (lower BC) projectiles, 6mm DTI is a fine cartridge. You're not going to be launching 108 gr high-BC projectiles from it, however. This cartridge is intended for longer distance shooting, so that's significant.

SIG isn't turning and burning on any products that use the 6.8 SPC case, bolts, etc.

They are competing for the NGSW with their own cartridge submission, which is a hybrid steel/brass .270-08 with a longer shoulder and more case capacity.

It has literally no relation to the 6.8 SPC other than bore diameter.

6.5CM, SIG .277 Fury, .308 Winchester


The .277 Fury uses the same case head diameter and profile as .308 Winchester, so you need an AR10 action, BCG, and magazine well to feed and contain it, along with major considerations for pressure containment over an AR10 since the chamber pressure is 80,000psi.

The problem with any of the 6x6.8-based wildcats and standardized Hornady 6mm Hagar is easy to see when you try to load them with VLDs and then fit them in the AR15:

6mm Hagar





The 6.8-based cases are too long when looking at AR15 magazine well constraints and long 105gr or higher high BC bullets that provide the type of supersonic reach, wind deflection, trajectory, and retained energy that snipers and DMs need to fill the gap in reach between riflemen and heavier sniper systems.

Even a 100gr TGT bullet in the 6x6.8 cases protrudes too much into the powder column, so you don't get meaningful increases in usable case capacity even when blowing the shoulder forward and playing with the shoulder angle.

Hornady already made 6mm Hagar with factory brass and it never caught on for the reasons above.  Case capacity is 37.5gr of H2O.

Since the Grendel/6mm AR/6mm ARC cases are shorter and fatter with a 30° shoulder, you have plenty of room for VLD/105gr and higher high BC 6mm bullets with an optimal location of the projectile base/shank-boattail junction to the SNJ of the brass.

The same is true for the .224 AR using the Grendel or 6mm PPC as you starting brass.  6mm PPC would be easier for start loads with a neck-size operation and light jam into the lands with light practice loads to fire-form.

Good stuff!

Sig has a longer range rifle based on a .308 casing for the 277 fury, right?  I thought they also had a 6.8 based smaller action carbine as well as a machine gun put out before the cross?  The MG-68 looks fun.

Looks as if the goal is running long heavy rounds, the squattier case is it. Doesn't the Grendel based setup still lose case capacity when parking that 107gn baby in it as well?

Sure, all cases do when loading, but you couldn't use that capacity even if you wanted - we're COAL and pressure-limited in these cartridges. There's no problem with case fill when using the appropriate powder (burn rates) in the longer bullets you'd want to use in magazine length loading. Remember, this is all a balancing act. Too many people fall into a trap trying to get maximum velocity, which is very different than maximum efficiency and often accuracy.

I haven't seen anything from SIG for the military that is 6.8 SPC.

They have a .277 Fury bolt gun for the civilian market, a .277 Fury AR10, and a belt-fed machine-gun for the 6.8 NGSW competition.

With 6mm Grendel, since the case is shorter, you can locate a 107gr ideally without pushing the shank down into the powder column.

The shoulder location is farther back on Grendel, 6mm AR, and .030" shorter even on the 6mm ARC.

If you look at 6.8 next to Grendel, it's the same basic story between 6mm variants of the 6.8 vs 6mm Grendel:

Cutaways always enlighten one, and put away his dreams.

So, if someone only was going to run lighter projectiles, the 6.8 variant would be better?

103gr Precision hunter round is 250.7gr, 16.24g.

Awesome, thanks man!

So the 108gr ELD should be around 16.57g.

That would then put the Loaded 24rd E-Lander w/ 108's @ 1.35lbs.

Having tried a bunch of 6mm wildcats, I look forward to the 6MM ARC. Factory brass and ammo is always nice. Everyone I know that was an early adopter for 6.5 Grendel has moved on to a 6mm Variant of Grendel or 6.8SPC. 6mm seems to be the sweet spot for 30ish grains of powder.

6x6.8 may not look as good and I wouldn't use it for bench rest, but it's practical and worked well enough when factory options were limited. Similar to 77s in a 223Rem. My TAC6 (6x6.8) is running 105s at 2650fps in an 18" barrel with sub MOA results at 600yds. I am loading to 2.275" which is mag length for unmodified PRI 6.8 mags. I didn't encounter pressure until 2750fps.

I have used 6mm Variants with excellent results on mule deer here in Colorado. Growing up hunting deer with 243Win using mild loads and old bullet designs, I see no issues using modern projectiles for hunting with the 6mm ARC. I personally wouldn't use it for Elk, but I didn't use my 6.5 Grendels either.

When some of big barrel makers get on the 6mm arc bandwagon. Who would you go to for a 20 or 22 inch barrel

White Oak

Eh: ish...

People figured out the Grendel a long time ago, and the 52k psi limit is there for a reason. Just because that isn't the pressure that primers start flattening/you get ejector marks, etc doesn't mean it's not viable at that pressure.



Those velocities with that bullet are plenty to get you out to 1000 out of an 18" barrel in an AR15 platform. This isn't a cartridge meant to replace the 6.5 CM, and for the intended purpose, it seems like it's going to do quite well. We'll all appreciate the better barrel life and part life of running it down at 52kpsi.

16.504g



6mm ARC, 108 ELD-M. Hopefully that's precise enough for you.

Awesome, thanks man! That is one hell of a scale

I'm having a few barrels spun up for 6mm ARC. What are people using for gas system length and port sizes for SBRs (10-10.5", 11.5") and 18" barrels?

If someone could come up with a pressure/time/barrel length graph from quickload for it, wouldn't be hard to figure it out.

Nvmd. Covered plenty.

I don't know the actual load spec's as no data is posted yet so just used a common powder for the 6mm AR and ran it to 52k psi

H4895 at 25.5 with 103-110gr projectiles in Hornady brass with CCI small rifle has been posted by another reloader on a different forum as a max load. This is not my load, so I can’t vouch for safety, but may be a good reference point for Quickload. Also interesting to see if it’s below the 52k cutoff, some people may already be hot-rodding.

Hmm thats crazy low pressure wise or the 37.5gr H2o that I was referenced by someone else is bogus. Calc'd 45k and 2380 ft/sec with a 108 eldm

I believe that was my post from the 'Hide.

25.5gr H4895 with a 108 gave 51,900psi in a pressure test barrel.

How does one do H2O volume?  Just weigh water until it fills with the scale zeroed out on an empty case?

ETA: I get 33.8gr H2O in an empty 6 ARC case.

Yes you measure water weight in a zero'd case.

I usually add a drop or two of soap to my test water so it helps break the surface tension of the water lowering it's meniscosity. A couple flicks to help release potential air bubbles is also wise.




Lowered case capacity to your 33.8gr measurment and then adjusted the temp of the powder to emulate roughly 52k psi(51,846)

I've seen 34.5-ish elsewhere (maybe on YT?) for measured ARC case capacity. With the case capacity set to 34.6gr, 25.5gr of H4895 with 108gr ELDs works out to right at 52ksi in QL without having to tweak much. Predicted velocity on a 24" barrel is only ~ 2,640 fps though. The fastest available powder that QL predicts is a crunchy (104%) charge of RL17 for right at ~2,745 fps.

I'm still going to try 6.5 Staball when I get an ARC put together, I think if you could get enough in it might be a good performer.

Oooh never heard of this 6.5 staball. I was like WTF is he talking about. Me likey....now to see if it's rare unicorn dust at the LGS

Is it in Quickload yet?

It's pretty new, I'm sure it's not in QL yet, it is pretty fine grained though, kind of like a ball version of RL16. I bought a few pounds but have only tried it with 190s in my .30-06, did well though.

How soon on barrels?  

Any recommendations?

Was going to build a 6.5G.....but this piques my interest

Depends on what you want. There’s a few places that plan to make them, but a smaller number that have shipped them out. Brownells had some exclusives, but believe they are sold out. There’s some custom makers, too. Probably a few months before anything is easier to come by, and fall before it’s more common.

Have you found any data for that powder for 6mmAR Turbo40 or fatrat? They are close enough it should give a good indication. I couldn’t find any when I looked, but I wasn’t digging that deep.

gavintoobe on YouTube has a video out that has some interesting information. In his comments there's a link to his webpage with some additional.

Thanks

I just saw Craddock can order one but about November to get it

Ok - I am all in on the Grendel - heavy 20 in and building a light weight 18 inch for hunting.  Also set up to reload - dies, bullets powder.  Have some 400+ rounds of ammo for it...

Was planning on getting a Ruger American Predator in 6.5 Grendel to play with as well.

Seeing this new cartridge come out...

Thinking what I will do is get a barrel in 6mm ARC and build an upper to play with - get into the reloading and also get set up to reload the 243 win as well - they would share bullets very nicely.

Red

Most of that was factual info, and they admitted the similarity to the wildcats. I don't see it being designed to be misleading or otherwise untrue, what did you disagree with/why are you calling it propaganda?