New 6mm Advanced Rifle Cartridge

Gtscotty · Jun 21, 2020

triumph001 said:
I can appreciate his effort though. He is rodding it a bit but at least he is transparent about it. My main interest is mostly due to the fact that there is finally a chambering that will fit in a Howa mini that is a little better than all the other factory options for my application.

Yeah, I don't care how he loads for his own guns, and I'm glad to see some data and user experiences getting out. I was just remarking that he's having to load a good bit over max to get close to advertised performance with H4895 (which should be a pretty good powder for the case). I'm guessing that to hit factory velocities within max pressure, reloaders are going to have to use temp sensitive ball powders like Leverevoloution or CFE 223. For temp in-sensitive powders you might top out 100fps or so less.

I do think a Howa Mini in 6mm ARC, would probably be a super fun compact rig.

tomcatfan · Jun 21, 2020

It looks like even factory ammo isn't getting the desired velocities necessary to reach out to 1000 yds unless you are hot or high.

Ledzep · Jun 22, 2020

How do you figure?

108 @ 2600 (18" barrel) is supersonic past 1000 at sea level.

tomcatfan · Jun 22, 2020

So the guy reloading In the video above got 2602 out of a 20" set up and he admitted to running hot. I’ve seen people say that factory ammo is running around 2550-2575. Maybe strelok is conservative, but my app say I’m transonic at 950 at sea level. It also says I get longer range from my 80 gr eld load.

Silverjay · Jun 22, 2020

I am getting 2590 with 108’s out of a 20” barrel with what Quickload says is right at 52k pressure. No pressure signs on the brass. Hodgdon Lever powder.

Rumblestrip · Jun 22, 2020

Gavin lives near the Washington/Idaho border I think. So, not sure what elevation he's at, but probably 4K above sea level I'd guess.

Ledzep · Jun 22, 2020

tomcatfan said:
So the guy reloading In the video above got 2602 out of a 20" set up and he admitted to running hot. I’ve seen people say that factory ammo is running around 2550-2575. Maybe strelok is conservative, but my app say I’m transonic at 950 at sea level. It also says I get longer range from my 80 gr eld load.

He's using one of the slower powders for the cartridge. You get another 125-150fps out of LeverEvolution or CFE223 at the same pressure. Don't take this the wrong way, but I wouldn't draw lasting conclusions on initial testing from someone flying blind.

Blaster7Romeo · Jun 22, 2020

Hope to see some more on the ground reports of FPS of factory ammo.. I was thinking of going 16inch and making a perfict little truck gun and getting rid if my 6.5G.. gonna give it some time to see how the factory ammo plays out..

ormandj · Jun 23, 2020

Ledzep said:
He's using one of the slower powders for the cartridge. You get another 125-150fps out of LeverEvolution or CFE223 at the same pressure. Don't take this the wrong way, but I wouldn't draw lasting conclusions on initial testing from someone flying blind.

Have you (or anyone else) tried something like StaBALL? Or is that too slow for the case capacity? This would be awesome powder if we could get enough in - but it's a bit slower than LeverEvolution (which I can't use due to temp instability).

Ledzep · Jun 23, 2020

I haven't seen/done any testing with StaBALL. I have got pretty decent speeds with CFE223, AA2520, and LeverEvolution, and for what my rifle is built for (300 and in hunting medium/small game) the temp/velocity variability isn't a huge concern for me. Best groups so far were with LeverEvolution, but it's pretty close between them. All sub-MOA for 10 shots, the lever evolution was .75 MOA for 10. Admittedly I can't shoot this little 8.4lb rifle as steady as I can my 22lb creedmoor.

I have heard (but no first hand experience) that RL-15 will get you some of the fastest speeds for extruded powders. Temp stability should be better than most ball powders.

ormandj · Jun 23, 2020

Ledzep said:
I haven't seen/done any testing with StaBALL. I have got pretty decent speeds with CFE223, AA2520, and LeverEvolution, and for what my rifle is built for (300 and in hunting medium/small game) the temp/velocity variability isn't a huge concern for me. Best groups so far were with LeverEvolution, but it's pretty close between them. All sub-MOA for 10 shots, the lever evolution was .75 MOA for 10. Admittedly I can't shoot this little 8.4lb rifle as steady as I can my 22lb creedmoor.

I have heard (but no first hand experience) that RL-15 will get you some of the fastest speeds for extruded powders. Temp stability should be better than most ball powders.

Wonder how Varget works, it should be right in there (slightly faster than CFE/Lever but just a touch slower than RL15) according to powder burn rate charts. Not sure how I feel about the guy in the video's testing.

Gtscotty · Jun 23, 2020

ormandj said:
Wonder how Varget works, it should be right in there (slightly faster than CFE/Lever but just a touch slower than RL15) according to powder burn rate charts. Not sure how I feel about the guy in the video's testing.

Varget is too bulky to be a top powder in the Grendel, I'd guess the situation will be the same in the ARC. The most popular temp-stable (ish) extruded powders for Grendel seem to be 8208 XBR, AR-Comp and H4895, all have a pretty good packing density.

When Winchester came out with StaBall 6.5, they indicated that it would be part of a series of more temp-stable ball powders. If they rolled out something like a ball version of Varget, or a temp-stable Leverevolution or Big Game next, it could be a great fit with the cartridge.

Hodgdon's most recent burn rate chart (attached) shows Staball 6.5 as being a bit slower than RL17 , but not too far away on the chart. QL predicts that RL17 would give top velocities in the simulated ARC if you could fit enough in, so StaBall seems like it would be worth a try anyway.

Ledzep · Jun 23, 2020

I've seen a couple of semi-conflicting results with Varget. I wish I had more specifics, but some have said it produces slow velocities, others that it'll give more speed than 8208 & 4895. It may be a contender. Hopefully some official published data will come out soon.

lennyo3034 · Jun 23, 2020

Ledzep said:
I've seen a couple of semi-conflicting results with Varget. I wish I had more specifics, but some have said it produces slow velocities, others that it'll give more speed than 8208 & 4895. It may be a contender. Hopefully some official published data will come out soon.

I've had both happen with different .223 barrels. One of them was fast with varget than 8208 and vice versa.

jbailey · Jun 23, 2020

has anyone tried or thought about 2000-MR in 6 ARC?

ormandj · Jun 23, 2020

Ledzep said:
I've seen a couple of semi-conflicting results with Varget. I wish I had more specifics, but some have said it produces slow velocities, others that it'll give more speed than 8208 & 4895. It may be a contender. Hopefully some official published data will come out soon.

Well, I've got Varget and H4895 here, so we'll see. Just waiting on my barrels to arrive... gonna be fun trying out a 10.5" in addition to an 18". Sure wish I could get my hands on a FL sizer from Forster yesterday, though.

Ledzep · Jun 23, 2020

Bear in mind this is a bolt gun only load, but after work today I was able to test out a couple of 103gr ELD-X loads, and 30.0gr of CFE-223 gave me the best accuracy (1.7" for 10 shots at 200yd) @ 2707fps with 11fps SD. 18" Bartlein 5R in a CZ 527. 1000ft-lb to 400yd, easy expansion velocity to 600+.

Cjt1983 · Jun 23, 2020

I got a barrel on the way for a bolt gun gonna see just how hard it can be pushed

yellowfin · Jun 24, 2020

steve podleski said:
Why this obsession with shooting a gas gun to 1000yd? Other than service rifle competition, if you are serious to shooting to 1000yd, use a bolt gun!

I personally don't have access to 1000 but my club does reach to 800ish and for me I just enjoy gas guns so much more than bolt guns for many reasons. Maybe I'm obtuse but to me I like something that I don't have to care as much about where my rifle runs out of juice. Other than .22LR I like whatever I pick up to be able to hit whatever I see to shoot at, just dial and/or hold more as needed. 77gr 5.56 is nice but if I can do better than that with the same trigger, stock, bipod, etc. that I already have the money spent on then I'm a lot happier than anchoring the money in a bolt gun that can't be multiple things.

Yondering · Jun 25, 2020

yellowfin said:
I personally don't have access to 1000 but my club does reach to 800ish and for me I just enjoy gas guns so much more than bolt guns for many reasons. Maybe I'm obtuse but to me I like something that I don't have to care as much about where my rifle runs out of juice. Other than .22LR I like whatever I pick up to be able to hit whatever I see to shoot at, just dial and/or hold more as needed. 77gr 5.56 is nice but if I can do better than that with the same trigger, stock, bipod, etc. that I already have the money spent on then I'm a lot happier than anchoring the money in a bolt gun that can't be multiple things.

Yup. Sounds like he's just stuck on a preconceived notion that gas guns aren't accurate. (LOL) There's no reason at all why the rest of us should use a bolt gun just because he thinks we should. I use a gas gun because I want to, I can, and it works well. End of story.

tomcatfan · Jun 25, 2020

Yondering said:
Yup. Sounds like he's just stuck on a preconceived notion that gas guns aren't accurate. (LOL) There's no reason at all why the rest of us should use a bolt gun just because he thinks we should. I use a gas gun because I want to, I can, and it works well. End of story.

Yep. I have some gas guns that are just as or more accurate than some of my bolt guns. Try sending 3 rounds to 1000 yds before you hear the first impact with a bolt gun.

Sutherlandsd · Jun 25, 2020

tomcatfan said:
Yep. I have some gas guns that are just as or more accurate than some of my bolt guns. Try sending 3 rounds to 1000 yds before you hear the first impact with a bolt gun.

this is the beauty of the Valkyrie very fast follow up shots. Mine is heavy as hell and has a 24”barrel and a 419 brake on it.. it doesn’t move at all. I really want to do the same thing with the arc, but I can’t lie that part of me wants to wait for a rarely used craddock valk barrel to pop on the exchange for like a hundred bucks since they are “obsolete” now. God bless cheap .224 bullet prices.

MichiganMitten · Jun 25, 2020

Ledzep said:
Bear in mind this is a bolt gun only load, but after work today I was able to test out a couple of 103gr ELD-X loads, and 30.0gr of CFE-223 gave me the best accuracy (1.7" for 10 shots at 200yd) @ 2707fps with 11fps SD. 18" Bartlein 5R in a CZ 527. 1000ft-lb to 400yd, easy expansion velocity to 600+.

Who made your Bartlein?

Ledzep · Jun 25, 2020

I spun it up myself. A little bit of a redneck operation, the thread pitch is 1.25mm (0.0492") and I ran 20 TPI (0.050" pitch) for 5-6 threads because the lathe only has imperial pitches and it fits. I had to buzz the shank down to ~1.09" diameter, and I set it up to shoulder off the receiver face with a flat breech. The factory setup is shouldered off of an internal shoulder with a bit of a breech recess.

In the vein of being technically correct, any GS that can do metric threads (especially anyone with CNC can do it) should be able to rebarrel one that's currently 7.62x39 or 6.5 Grendel. I don't know if any proper smith is going to stand behind my 20TPI shenanigans...

yellowfin · Jun 25, 2020

tomcatfan said:
Yep. I have some gas guns that are just as or more accurate than some of my bolt guns. Try sending 3 rounds to 1000 yds before you hear the first impact with a bolt gun.

Speed is nice but for me it's more the consistency of not having to break cheek weld and grip and be distracted by doing anything other than watch the target, focus on my mechanics, and keep sending them. Same reason I shoot suppressed 100% of the time with a rifle except for rimfire.

yellowfin · Jun 25, 2020

Gtscotty said:
Yeah, I watched that, I used 6mm AR as the base and subtracted like 1.5gr to play with some numbers. Unless I missed something, UR is loading way over pressure to hit velocities though, an estimated 61 ksi in QL. He had some verbiage that flashed up on the screen saying that QL predicts peak pressure and SAAMI specifies Maximum Average Pressure MAP, insinuating that the values measured are different. As far as I know, the "Average" in MAP is the average over some sample size, or a batch, not some kind of average of a single curve.

Given that he's hitting velocities similar to his 61 ksi QL prediction, I think it's reasonable to guess that he's way over pressure. Also I read on the forums somewhere that 25.5gr H4895 in a pressure barrel gave 51.9 ksi, UR is loading 26.6gr, another indication that he's probably way over pressure.

Pressure is specific to an individual chamber though, isn't it? There's often a difference in published load data between companies because of this, such as a difference between Hornady's data and Hodgdon's data for the same combo of powder and bullet, as I understand. Could have a different OAL thus more or less jump thus more or less pressure, as observed between .223 and 5.56 chamber spec as one example.

Ledzep · Jun 25, 2020

Powder lot-to-lot variance, case variance from maker to maker, changing primers, fouling, temp, bullet bearing surface length, bore/groove diameter variation, and reamer variation can all play a role in pressure/velocity variation from one setup to the next. On the end user side, seating depth definitely changes pressure curves.

Generally speaking though, it's pretty consistent if you use the same components. Powder lot-to-lot variation will cause the biggest fluctuation if all the same components are used as what's on the published load data. I suspect it's also the biggest contributor to differences between two different load manuals having different data.

janttony · Jun 25, 2020

Another ARC being tested.

trdjohn · Jun 25, 2020

janttony said:
Another ARC being tested.

my take away from that video, there didn't seem to be any issues with running the magazines...think that was brought up way earlier in this thread?

janttony · Jun 25, 2020

trdjohn said:
my take away from that video, there didn't seem to be any issues with running the magazines...think that was brought up way earlier in this thread?

I agree, however, I think a lot of people are waiting for widespread testing of 25 round magazines and their reliability. I’m wondering if Amend 2’s design will be adapted in the future to be able to get higher round count mags.

Silverjay · Jun 25, 2020

I have run Elander 17’s and C products 10’s with no issues. Roughly 100 rounds through each so a smaller sample size.

janttony · Jun 25, 2020

Silverjay said:
I have run Elander 17’s and C products 10’s with no issues. Roughly 100 rounds through each so a smaller sample size.

My 17 round E-lander has run flawlessly as well...besides having a weird rattle sound when you have more than 5 rounds in the mag. Honestly, the only reason why I’m contemplating getting one of the Amend 2 mags is so I don’t have that metal on metal sound of the mag against the magwell when I’m on the deer stand.

alamo5000 · Jun 25, 2020

Definitely following this thread. I am extremely interested in this.

On that latest video that janttony put up it looks like his velocity matches up nicely with what is advertised. I did some reverse math with a calculator when he told how much dial up he needed at what ranges.

Ledzep · Jun 26, 2020

Most of this has probably been covered here already but I didn't see it posted yet.

jbailey · Jun 26, 2020

So I'm looking for a new 'farm gun' with steel and critter needs out to about 800yds. Looking to upgrade my 223 options (a 20" bolt gun and 15" AR15). 6ARC looks great. Sending a 105gr Hybrid at 2700 will be a serious upgrade.

Considering the Rock Creek from Craddock Precision

22" 6mm ARC Rock Creek Barrel

craddockprecision.com

DOES ANYONE HAVE ANY REVIEWS ON CRADDOCK???

Thanks

Sutherlandsd · Jun 26, 2020

Craddock is full of TN goodness.

Edit: one of the best imo

tomcatfan · Jun 26, 2020

Sutherlandsd said:
Craddock is full of TN goodness.

Edit: one of the best imo

Is their 14-16 week lead time legit? I appreciate how upfront they are, but I’m looking for something a little sooner.

ormandj · Jun 27, 2020

tomcatfan said:
Is their 14-16 week lead time legit? I appreciate how upfront they are, but I’m looking for something a little sooner.

Yes, and it’s not much better anywhere you will get a custom barrel made. Everyone is swamped right now. Much like planting a tree, the best time to order a barrel was 20 years ago, the second best is now. Craddock has an amazing reputation for a reason, and to me, it’s worth waiting for.

If you want something sooner you’ll need to go with a bulk producer in a spec barrel, keep your eye on brownells and so forth. It won’t be nearly as nice a barrel but unless you are shooting half MOA or better and care about that kind of accuracy, it’ll be fine. You’ll pay less, so there are advantages.

I prefer to wait.

Silverjay · Jun 27, 2020

Data from 95 grain Berger classic hunter and CFE223. Work up slow if you base off of this.

28.0 2,624
29.0 2,688
29.4 2,722
29.6 2,773
29.8 2,795
30.0 2,808
30.2 2,811
30.4 2,838
30.6 2,886
30.8 2,881
31.0 2,917 Quickload predicts pressure at 52,500 (used 6mm AR and adjusted case volume)
31.2 2,901
31.4 2,929

Ejection pattern shifted from 4:00 to 3:00 at 31.0 grains and higher. The case and volume data I used for 108 ELD’s gave almost exact velocities, same cartridge data for this load predicted 2,720 at 31.0 grains and actual was 200 FPS faster. No pressure signs on the brass. Primers are S&B SR and still have nice rounded shoulders. No ejector marks.

Across a 10 round set of 31.0 grains the average velocity was 2895 with an SD of 6. This is at 93 degrees F ambient.

mark5pt56 · Jun 27, 2020

Silverjay said:
Data from 95 grain Berger classic hunter and CFE223. Work up slow if you base off of this.

28.0 2,624
29.0 2,688
29.4 2,722
29.6 2,773
29.8 2,795
30.0 2,808
30.2 2,811
30.4 2,838
30.6 2,886
30.8 2,881
31.0 2,917 Quickload predicts pressure at 52,500 (used 6mm AR and adjusted case volume)
31.2 2,901
31.4 2,929

Ejection pattern shifted from 4:00 to 3:00 at 31.0 grains and higher. The case and volume data I used for 108 ELD’s gave almost exact velocities, same cartridge data for this load predicted 2,720 at 31.0 grains and actual was 200 FPS faster. No pressure signs on the brass. Primers are S&B SR and still have nice rounded shoulders. No ejector marks.

Across a 10 round set of 31.0 grains the average velocity was 2895 with an SD of 6. This is at 93 degrees F ambient.

Barrel length, rifle?

Silverjay · Jun 27, 2020

mark5pt56 said:
Barrel length, rifle?

20” AB barrel from Brownells. I put it in a Larue built 6.5 Grendel.

tomcatfan · Jun 28, 2020

Silverjay said:
20” AB barrel from Brownells. I put it in a Larue built 6.5 Grendel.

What kind of accuracy?

Silverjay · Jun 28, 2020

I was shooting steel, not paper. I was on a 8” steel at 800 6 of 10 rounds with 8-11 mph wind. Can’t be too bad. I will be testing groups in the next few days.

Ronin_1 · Jun 28, 2020

LRRPF52 said:
Since 6.5 Grendel was targeting both the hunting crowd first, followed by the target crowd, 6.5mm was the right choice for bore diameter/projectile availability. The marketing concept focusing on hunting first was designed to establish more widespread traction since hunting rifle purchases were the main factor in people buying rifles still in the early 2000s, and are probably still that way today.

If it would have been limited to a High Power X-ring scorer and varmint cartridge, 6mm would have made more sense, but would have not realized the same marketability for those wanting to shoot larger game. At the time, it was already a stretch for a lot of Americans to even consider using anything smaller than .308 Winchester, since most were ignorant of the century of success of the 6.5x55 Mauser and early 1900s success of the 6.5x54 Mannlicher-Shoenauer.

Bill A. was also looking at doing a .257 Grendel, but there was hardly any projectile availability for the quarter bore for any target work, whereas 6.5mm had a boat load of exiting projectiles.

The major problem with the Grendel was that it was kept as a proprietary cartridge initially and the cost of ammo was prohibitive in DoD quantities.

There were other issues, but that was the biggest.
Thereafter the Grendel was market for multiple civilian roles.

jbailey · Jun 29, 2020

The 95gr is an attractive option at those MVs, for me... my farm gun will be out to 600yds most of the time, maybe upwards of 800yds.

I just ordered from Craddock, so thanks for the above reviews/feedback.

My barrel build details in case anyone is interested in the price and the options:

6mm ARC Rock Creek
(Gas Block Diameter: .875", Length: 20" +2 Rifle, Accessories: SS LoPro Gas Block & Tube (+$42), Thread Size: 5/8x24, Time and Blended Muzzle Brake: Yes(+$50), Fluting: None, Barrel Finish: Bead Blast, Complete Headspaced Bolt: Yes w/ Carrier (+$107), I Acknowledge: Yes)

1

$564.00 USD

$564.00 USD

Silverjay · Jun 29, 2020

When I tried Quickload to those velocities, the pressures at 31.0 grains of CFE223 is closer to 60k. Based on that truing, it looks like 30.0 grains will be 53-54k psi. 30.0 grains shot and grouped well.

Crews · Jun 29, 2020

So, if my lifestyle choice is 11-12”(ish) AR-15 barrels and shooting factory ammo at thin skinned animals out to 300 yards......

Does 6 ARC do anything better that 6.5 Grendel?

For instance, I’d be completely content if someone told me the whole damned thing is a wash, but recoil is noticeably less.

Ledzep · Jun 29, 2020

Probably going to be pretty much a wash energy/velocity/trajectory wise within 300-400yd. The ARC will be flatter with less wind, but over that distance it's not going to amount to make-or-break numbers. Grendel will have the nod for energy, but only in the ball park of 100ft-lb, and that lead will diminish over range. I suspect recoil will be slightly less with the ARC, but not a ton.

Crews · Jun 29, 2020

I believe I’ll just go with Grendel then.

On edit.... for 300 yards and in where BC isn’t king, I wonder if 6ARC has the advantage when it comes to downloading below 100 grains of bullet weight?

You basically can’t do that in Grendel unless you go with a varmint bullet. I’m not familiar with 6mm but just looked on Midway and there’s a metric ton of legit hunting bullets smaller than a hundred grains.

FishinGuns · Jun 29, 2020

I’m doing a 20” Grendel hunting rig and was going to do a 18” ARC hunting rig - Grendel 120’ish gr for deer and ARC in the 80’ish-90’ish gr. range for varmint, but I’m going to hold off and do an 18” .223 Wylde instead of ARC. Think I’ll let ARC teeth for a bit and if it turns out to be the second coming, I’ll rebarrel then. I don’t roll my own at this point, either.

I’m still interested for sure, but I’m a gas block and suppressor cover away from my Grendel being ready to sight-in. I’m also heavily invested in 5.56, so with the vast similarity between 6.5G and 6ARC, I’m sitting back and seeing how this plays out now.

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