10 shot groups in the .8" to 1.1" range at 100yd. I have 70 rounds on it so far.
@Yondering yes. ignoring wind, which isn't drastically different within 400yd, drop for 100-400 is pretty similar among many calibers.
-
Having trouble using the site?
Contact support
New 6mm Advanced Rifle Cartridge
- Thread starter Gtscotty
- Start date
10 shot groups in the .8" to 1.1" range at 100yd. I have 70 rounds on it so far.
@Yondering yes. ignoring wind, which isn't drastically different within 400yd, drop for 100-400 is pretty similar among many calibers.
Sure, you might as well claim a 308 and 243 have about the same trajectory too in that case.
I said similar, not the same. FWIW, .243 and .308 are within 1 MOA of each other to 400yd if you use similar class bullets... It's some master of the obvious material to say that substantially different velocities will produce different trajectories. Most stuff we shoot is in the 2700-2950 range and it's the same drill. .4 mils at 200, 1-1.2 mils at 300, 2-2.2 mils to 400, 2.5-3 to 500, etc.. I'm done entertaining this one. You can run the JBM machine and determine for yourself what "similar" means. Don't be a troll.
on a different note... I've got 18" Odin in 6mm ARC, and their clamp-on adjustable gas block...used it yesterday in a lower with a carbine H buffer, no issues with ejecting rounds, no issues locking back on empty mag (20 round grendel duramag)...before I assembled it I could just barely get #38 bit (~0.101) in the gas port, that's how mine came from Odin. My gas block is 10 clicks out from fully closed in the H buffer lower. Swapped it over to another lower that has H3 carbine buffer, had to open the gas block about 17-18 clicks from closed (there are roughly 20 clicks from closed to open)
GA Precision looks to still have some 108gr in stock.
I got some from them recently, and some Hornady Black more than a month ago when it was out there. Haven’t seen brass for sale yet.
Hornady 6mm ARC 108 ELD-M
<p>Hornady's newest cartridge the ARC (Advanced Rifle Cartridge), developed for U.S. DoD for its multipurpose combat rifle program.</p>
www.gaprecision.net
My GAP ammo delivery is scheduled for today ... Just waiting on Craddock now! It's only been 5 weeks or so though.
Same here on my 21" barrel from Odin Works. I’ll put the upper together, but unfortunately with vacation next week, I won’t be able to shoot it for a while.
Just put the first 20 rnds down the same barrel with factory 108’s . It held 1/2 to 3/4 MOA at 300. I was pleasantly surprised with the speed but am also running a ultra 7 on it.
Attachments
Anybody with Quickload and a ARC cartridge design mind running some numbers on the 108 with AR Comp? I’m trying to get an idea of max load without exceeding 52kpsi but it unfortunately does not appear to have been tested.
I’m honestly at a bit of a loss reloading for this cartridge without pressure barrels since the normal reloading signs won’t show up until well north of 52kpsi.
I’m honestly at a bit of a loss reloading for this cartridge without pressure barrels since the normal reloading signs won’t show up until well north of 52kpsi.
Last edited:
Hornady just released MORE load data, including Bolt Guns... https://www.hornady.com/assets/site/hornady/files/load-data/6mm-arc-bolt.pdf
Got my 21” Odin Works upper yesterday. It certainly appears top notch. Now just need to make some time to get out and shoot it.
Rifle finished with an Aero lower including a Larue trigger, and Odin Zulu stock, topped with an Athlon Argos BTR Gen2 6-24x50.
Rifle finished with an Aero lower including a Larue trigger, and Odin Zulu stock, topped with an Athlon Argos BTR Gen2 6-24x50.
Last edited:
I got my 21" Odin works barrel in, but fire restrictions here in Northern AZ are preventing me from shooting.
I'd say not if you're using Lever, but something doesn't seem right about the numbers Hornady published. Depends a lot on what powder you're using though; it'd be too hot for sure with most any other powder except maybe CFE223. Also, the Berger 95 VLD is a whole different shape than their 95-100gr bullets listed, with a lot less bearing surface; I'm not sure their data really correlates to that bullet very well in my experience.
For example, in my 243 LBC (again, almost the same thing, just a hair more case capacity) comparing Hornady's data for the 105 BTHP and Lever, using the same max charge weight, same bullet, and more case capacity, I'm seeing ~150 fps more than they show. Granted that's in my 19" barrel vs their 18", but the difference shouldn't be that much and even my 12.5" barrel is only 100 fps slower than their 18" velocity, for the exact same load. The extra capacity of my cartridge should give less velocity, not more, if all else is equal. Of course things are never equal, but their velocity numbers seem low. The charge weights appear to be right on track with what I've been using though.
Has anyone else noticed that many of the groups posted on YouTube exhibit vertical stringing or else are double grouping (3 and 2) even though the overall group for the 3 & 2 groups is OK.
I have also noticed a number of the close up video shots of the group showed the point of the bullet not in the middle of the bullet hole (on paper) although the holes were not badly egg shaped.
I am wondering if 1:7.7 or 1:7.5 twist barrels are fast enough for 108-110gr bullets?
I have also noticed a number of the close up video shots of the group showed the point of the bullet not in the middle of the bullet hole (on paper) although the holes were not badly egg shaped.
I am wondering if 1:7.7 or 1:7.5 twist barrels are fast enough for 108-110gr bullets?
Twist Rate Stability Calculator
Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.
bergerbullets.com
I'd say 7.5 would be for the vast majority of conditions. You lose a couple of percentage points on 7.7, but not enough that it should make that big of a deal.
Bullets are plenty stable. The initial lot of 105 Black ammo was loaded a bit too long and jams into lands. I've noticed that jammed rounds tend to string vertically, which may be some of what you're seeing. I've not noticed any stringing in my AR. I do see more random fliers than with my bolt gun (nothing surprising there), but groups are generally round.
ETA: 103 Vapor Trails w/AA2520.
ETA: 103 Vapor Trails w/AA2520.
Last edited:
Have been reading @Ledzep and other's posts on this thread. Just put together my own 6mm ARC AR-15 and am beginning load development. Nice looking group you shot up there. Was that 100 yards with an AR or a bolt gun?
My goal is to find a 1/2 MOA or better load that feeds out of the magazine in my AR-15 platform. I'd like to be able to reach out to 1000 yards with that platform. This is for shooting steel and as I plan on using 108 ELD-Ms or 105 Berger Hybrid Targets, 2550 FPS will achieve the distance part of the goal.
I tried a Ballistic Advantage barrel but couldn't the accuracy I was looking for out of it. Interestingly, I did shoot some 108s at 900 yards using that barrel and even at 2550 FPS with Varget, it did great. I was shooting a 2 MOA steel target (18").
Just to qualify myself as someone who can reload and shoot sub MOA, I shoot F-T/R competitively and hold a current NRA High Master rank in Midrange (600 yard) F-T/R. That said, I will freely admit that I shoot a bolt gun much more comfortably than an AR-15 but am willing to learn.
I have only broken in my new 21 & 3/4" barrel. It is a 7.7 twist Wilson. I used Varget and 108 ELD-Ms to do that. After the 20 or so break-in rounds I did shoot three 5-shot groups with with a charge of 27 grains of Varget. Speed was in the 2626 FPS range as measured by Labradar but the barrel is still new and will likely speed up a little. SDs were in the high single digits with this charge. Group size of the 3 groups were .9, .7 and .3 MOA at 100 yards.
Just for comparison, I did shoot two 5-round groups with Hornady Black 105g factory ammo. I shot groups in the 1.4 and 1.1 MOA range at 100 yards with them. Speed was 2700 and 2705 FPS with SDs of 21.8 and 17.3. This ammo shot 2 MOA groups in the previous barrel.
In the previous barrel I switched to CFE223 to get more speed w/o pressure and will do that with this barrel as well.
I don't want to compare a bolt gun to a gas gun as the pressures could be significantly different. I'd like to stay near the 52000 PSI limit.
What are the best consistent group sizes you and others are getting out of an AR-platformed 6mm ARC or similar 6mm Grendel-or variant cartridge and what powder and projectile are you using to get that?
I am not asking for load data, just interested to know what is reasonable so far.
Thank you all,
Henryrifle
My goal is to find a 1/2 MOA or better load that feeds out of the magazine in my AR-15 platform. I'd like to be able to reach out to 1000 yards with that platform. This is for shooting steel and as I plan on using 108 ELD-Ms or 105 Berger Hybrid Targets, 2550 FPS will achieve the distance part of the goal.
I tried a Ballistic Advantage barrel but couldn't the accuracy I was looking for out of it. Interestingly, I did shoot some 108s at 900 yards using that barrel and even at 2550 FPS with Varget, it did great. I was shooting a 2 MOA steel target (18").
Just to qualify myself as someone who can reload and shoot sub MOA, I shoot F-T/R competitively and hold a current NRA High Master rank in Midrange (600 yard) F-T/R. That said, I will freely admit that I shoot a bolt gun much more comfortably than an AR-15 but am willing to learn.
I have only broken in my new 21 & 3/4" barrel. It is a 7.7 twist Wilson. I used Varget and 108 ELD-Ms to do that. After the 20 or so break-in rounds I did shoot three 5-shot groups with with a charge of 27 grains of Varget. Speed was in the 2626 FPS range as measured by Labradar but the barrel is still new and will likely speed up a little. SDs were in the high single digits with this charge. Group size of the 3 groups were .9, .7 and .3 MOA at 100 yards.
Just for comparison, I did shoot two 5-round groups with Hornady Black 105g factory ammo. I shot groups in the 1.4 and 1.1 MOA range at 100 yards with them. Speed was 2700 and 2705 FPS with SDs of 21.8 and 17.3. This ammo shot 2 MOA groups in the previous barrel.
In the previous barrel I switched to CFE223 to get more speed w/o pressure and will do that with this barrel as well.
I don't want to compare a bolt gun to a gas gun as the pressures could be significantly different. I'd like to stay near the 52000 PSI limit.
What are the best consistent group sizes you and others are getting out of an AR-platformed 6mm ARC or similar 6mm Grendel-or variant cartridge and what powder and projectile are you using to get that?
I am not asking for load data, just interested to know what is reasonable so far.
Thank you all,
Henryrifle
My group above is out of my 18" AR-15. I have only really broken the barrel in, about 80 rounds of various stuff I've thrown together with CFE223, AA2520, and LeverEvolution. LeverEvolution and AA2520 seem to be decent for me so far in the AR, and LeverEvolution is what I also use in my bolt action.
I only expect AR's to group about 1.25 MOA. I have done it before, but usually get fed up trying to consistently get better than that with gas guns so I moved my baseline on expectations vs. happiness plot.
I only expect AR's to group about 1.25 MOA. I have done it before, but usually get fed up trying to consistently get better than that with gas guns so I moved my baseline on expectations vs. happiness plot.
I understand expectation vs. happiness plot but suspect you are only tricking yourself for short periods of time
That group looks like a .5 MOA group assuming 100 yards? I was not counting the one hole out of the group to the right.Thanks for the reply!
henryrifle
Yessir, 100yd. Everything under 1.25 MOA I attribute to luck. This rifle has frequently produced touching 3 and 5 shot groups, but also throws a few that are a touch over 1 MOA. I've found ways to bind the handguard that produce 2-2.5 MOA fliers on barricades, too. If I were to lay down and shoot a bunch of 10-shot groups I'd expect the average to be something more like 0.8-1.0" with a few in the 1.5-1.6" range which is stellar in my opinion. I used to try to get AR's to do 1/2 MOA or 3/4 MOA... 1.5 is acceptable, 1.2 is great, 1.0 or better is gravy.
The 18" barrel was shooting factory 108's at 2596fps before I ran out of them. I haven't chrono'd most of my reloads, but was in the 2600-2620fps range with LeverEvolution and 103 ELD-X's.
The 18" barrel was shooting factory 108's at 2596fps before I ran out of them. I haven't chrono'd most of my reloads, but was in the 2600-2620fps range with LeverEvolution and 103 ELD-X's.
I'm really excited about this new AR 15 6mm chambering. Not as a long range option, I'll stick to my 6 creed bolt rifle for long range use, but as a predator/small game option. I'm ordering the Proof 18'' carbon barrel to swap out with one of my JP SCR-11 223's. I have chosen Proof as I have 2 6mm carbons on hunting rifles that all shoot .5moa with Berger 105VLDH, so I have no doubt the Proof barrel will be a winner. Plus keeping weight down with the SCR is a priority. Ill plan to began working with the Berger 87gr VLDH. If that bullet doesn't work out for me, (poor accuracy or poor terminal performance on pigs) ill go with the 105VLDH that has been the most 6mm effective hunting bullet for me. So happy I continued to put off converting my 6.5 Grendel's to 6 Grendel. I hope we finally have the perfect AR15 for both long range shooters and predator hunters.
Alright. I am getting a little happier. Shot some tests today with Varget and CFE223, results above. Need to test a few increments more with Varget as it looks like the group was just starting to tighten.
CFE223 did okay today too. I need to test both a little less powder and a little more powder.
All of these groups were shot with Hornady 108 ELD-Ms loaded to a COAL of 2.260". I shot from prone with a Nightforce 5.5-22X50 scope using an F-Class bipod and rear bag and an Accu-Wedge!
It did start raining during the last few groups of the CFE223, and, to be honest, the rain was heavy enough to make the target somewhat blurry. The last target may have been somewhat lucky.
Quick range report on my 21" Odin Works barrel in 6 ARC. It has a +2 gas system and a 1-7.5 twist barrel. Only thing I can say so far is that the barrel far exceeds my expectations. With that being said, as you guys know ammo is crazy hard to find, so I only shot 14 rounds to sight in and get preliminary velocities. I want to save some ammo for long range shooting. This isn't a comprehensive review, but it certainly shows promise.
The first two groups were with a magneto speed attached to my Omega. The first one is only a 3 shot group, the other two are 5. Over the first 9 rounds I averaged 2740 ft/sec with an ES of 36 and an SD of 12.2 with factory 108 ELD match ammo. I took the magnetospeed off and I shot the last group to confirm zero.
The velocity exceeded my expectations and the accuracy of the barrel was downright impressive. As more ammo becomes available, I'll shoot some more.
The first two groups were with a magneto speed attached to my Omega. The first one is only a 3 shot group, the other two are 5. Over the first 9 rounds I averaged 2740 ft/sec with an ES of 36 and an SD of 12.2 with factory 108 ELD match ammo. I took the magnetospeed off and I shot the last group to confirm zero.
The velocity exceeded my expectations and the accuracy of the barrel was downright impressive. As more ammo becomes available, I'll shoot some more.
That is looking good, tomcatfan! You're barrel will likely pick up more speed as you get more rounds through it. I have not been able to get my hands on 108 ELD-M factory ammo but your velocity is awesome!
I'll go look but if you haven't posted earlier in this thread can you tell us something about your rifle and how you are shooting it?
Looking forward to your next post.
henryrifle
I'll go look but if you haven't posted earlier in this thread can you tell us something about your rifle and how you are shooting it?
Looking forward to your next post.
henryrifle
I wouldn't say there is anything special about the build.
The lower: YHM lower, ergo grip, luth AR MB1 stock, a triggertech independence special trigger, and Cproducts defense 10 round magazine. The trigger is actually incredible for the $150 I paid for it, very consistent feel.
The upper: AR Stoner upper, midwest industries 18" suppressor ready handguard, 21" odinworks barrel, odinworks adjustable gas block and tube, brownells 6.5 grendel type II BCG, ASR brake, Vortex Strike Eagle 5-25 in MOA, and a Leapers UTG 34mm scope mount.
I got the longest handguard I could find as I didn't want a lot of the barrel showing and I wanted the gas block covered. The 0.875 odinworks adjustable gas block doesn't fit under many handgards.
I was just shooting it with a LRA bipod on the front, a silencer-co omega mounted to it, and a rear bag in the back.
I shot it before and after my AR-10 in 6.5 CM, and the 6 ARC is considerably softer shooting than the AR-10. I was surprised how much difference there was. Both rifles have adjustable gas blocks for the can.
Looking at the ballistics between the two, the 6ARC takes less elevation and has the same windage hold at 1000 yds as my 6.5 CM shooting 140 grain american gunner. The 108 eld is going 2750 fps out of a 21" barrel, and 140 grain AG goes 2650 fps out of my 20" faxon barrel on the AR-10. When comparing the 6ARC to my 140 eld handloads, the 6 ARC has 0.8 moa more elevation hold than a 140 eld going 2690 fps. For something that is softer shooting and can be shot out of a small frame AR, I think the 6ARC will be very popular. Granted, I have almost no rounds down this barrel yet, so I guess time will tell.
The only 10.5" I have presently is a 5.56. A 10.5"-12" in 6mm ARC offers about the same trajectory (slightly flatter) but twice the bullet weight, with some of the current festivities in mind I'd expect a 90 grain GMX from a 6mm ARC "pistol" to do a LOT better through sheet metal and safety glass than most if not all 5.56 from an equal barrel length
. Read the whole thread up to here, took me a few days . In a general way I am a 6mm bore devotee anyway, real world it is head and shoulders above most .224 bore stuff on varmints ;-). 6-284 with 75 vmax has been a long time favorite.
Last edited:
You are pretty modest. That is a very nice build.
Not trying to drift off topic but do you have any concerns about the gas block hitting the hand guard when loading the bipod? I was sure this was part of an accuracy problem with a previous build and actually hacksawed off about 3" of hand guard. That sounds terrible but after some finishing and cerakote you can't tell. That did not solve the problem but I now leave the gas blocks exposed on most of my builds just in case.
Your barrel may be faster than mine as I am only getting 2700 FPS out of factory 105 Black ammo. Have not been able to purchase any 108 Match ammo yet.
What I have found is that 29.2 grains of CFE223 behind a 108 ELD-M loaded to magazine length in my 21.75" barrel produces a MV of 2669 FPS as measured by Labradar. I believe this is very close to a maximum charge in my rifle as the brass does show the beginning of mild ejector flow.
I have been shooting converted 6.5 Grendel brass and so far have only shot virgin brass. Trying to cycle through all 200 rounds to get to a big enough stockpile of once-fired brass. My experience though is that virgin brass requires a few more tenths of powder to equal MV of fired brass.
Very interested in what you are planning for handholds for the 6mm ARC.
Henryrifle
I just took the plunge. Ordered a BCM upper and an Odin 18” barrel w/ BCG and gas system. The Odin is out of stock, but it’ll get here when it gets here. Deer season is close, so I’ll be playing with the 350 Legend for a while anyway.
I might add a carbon fiber hand guard, but I have a 12.5” Odin that I’m not using right now.
Of course, a new rife will necessitate a new suppressor and optic also. Where will it all end?
I might add a carbon fiber hand guard, but I have a 12.5” Odin that I’m not using right now.
Of course, a new rife will necessitate a new suppressor and optic also. Where will it all end?
I know many people would disagree with me, but generally I don’t load bipods. I just let the rifle sit under its own weight up front and drive it from the back with what ever bad I‘m using. I’m not a world class shooter by any means, but I’ve had good results with that method. I’ve tried the bipod loading method and it just didn’t work for me.
I’m a couple of months away from reloading. I’m off at school and all of my gear is at home. I‘m planning on trying leverevolution, and the 108 ELD. It’s going to be hard to keep pressure below 52ksi as it will really be just a guess, there shouldn’t be any pressure signs until well above that pressure. I’ve got 200 rounds of factory ammo on back order from Midwest shooters, but who knows how long that order will take. We’re living in crazy times right now.
I personally disagree, but it all depends on the rifle, and barrel. If you're using a handguard that isn't extremely sturdy, and have a thinner barrel, and have minimal clearance, between flexing from heavy bipod loading and barrel whip you can have a bad time. Something else important to note - many people have a bad idea of what bipod loading means. It doesn't mean leaning into the bipod and forcing it into a fixed position under a lot of stress. You're literally just trying to take out any slack and no more - there should be VERY LITTLE pressure on the bipod.
Most people I see are really putting some weight into the bipod, and that's completely unnecessary and absolutely can cause issues with handguard flex. Either way, if not loading works for you, then keep at it! I just suggest a very light loading to take out any slack from the system for most shooters.
No need to guess with LeverEvolution, just use the load data. It's temperature sensitive, so watch velocity. I don't know what temperature they measured those loads at, so that's something to be aware of - but you should be able to stay around 52kpsi fairly easily that way.
From what I understand, leverevolution is less temperature sensitive than cfe223. But sticking to load data is what concerned me. Hornady’ s velocities seem low based on published data. I was hoping they were being conservative.
Spent some time at the range today and based on results from Friday, I thought I had a good idea of a good load. I was looking forward to posting up some pics of target pages filled with .4s and .5s.
It didn't turn out that way.
From all the data I have collected, 28.1 to 28.3 grains of CFE 223 behind the 108 ELD-M produce the most consistent groups--not the most accurate but almost always less than 1 MOA. The average, so far is .81 MOA.
In all honesty, I am struggling with consistently holding the rifle the same way from group to group. Shooting a bolt gun is much easier. I tried a few different things today and some clearly didn't work. I changed my hold to a more aggressive front bipod load on the second sheet to ill-effect. Not a smart thing do while looking for a load so, I'll have to retest some of that...
Results from the day:
It didn't turn out that way.
From all the data I have collected, 28.1 to 28.3 grains of CFE 223 behind the 108 ELD-M produce the most consistent groups--not the most accurate but almost always less than 1 MOA. The average, so far is .81 MOA.
In all honesty, I am struggling with consistently holding the rifle the same way from group to group. Shooting a bolt gun is much easier. I tried a few different things today and some clearly didn't work. I changed my hold to a more aggressive front bipod load on the second sheet to ill-effect. Not a smart thing do while looking for a load so, I'll have to retest some of that...
Results from the day:
Was able to snag a box of 105 BTHP off of a friend and shot it in my 18" Proof AR Saturday. 10-shot group was roughly 1.2" at 100yd, Avg velocity was 2672. Was able to tag 2 MOA plates at 600yd pretty easy, didn't shoot at anything further. There's a coyote plate at 300yd and was able to smack the head 5/5. I think it's going to be a fun winter
I get very similar results to yours with that ammo out of my 21.75" barrel. 2700 FPS and 1.1 to 1.5 MOA at 100 yards. SD was between 17 and 21.
Henryrifle
My experience is with 6 Creed, but I found that the 108 Match is loaded hotter (like 100FPS in my case) than the 105 Black. This is only speculation, but I would guess that is by-design since the Match ammo is (generally) targeted to bolt guns and the Black is targeted to gas guns.
Last edited:
I agree with you, SupressYourself. That matches my experience too, however, I would not imagine that Hornady would load either over the SAAMI spec pressure, and, as such, I would expect both to be loaded to the most accurate "hottest" load they were able to produce.
Henry, do you have a PDF or file of your targets? I like those. Mine are similar, but its always nice to have options.
I've been shooting a 6 grendel for about a year and have settled on benchmark. Not the fastest, but I like to get the most temp stable stuff I can. Plus, I can actually find it in stock sometimes. 8208xbr was good as well.
I've been shooting a 6 grendel for about a year and have settled on benchmark. Not the fastest, but I like to get the most temp stable stuff I can. Plus, I can actually find it in stock sometimes. 8208xbr was good as well.
I attached it here. I print this out of PowerPoint. Let me know if this works or not. The red 1" arrow at top print out exactly 1" for me from powerpoint. The grid is a little off even though the ruler says it is 1" in PowerPoint.
I am unable to attache the PowerPoint slide.
Please let me know if this works...
I am unable to attache the PowerPoint slide.
Please let me know if this works...
I hope they can keep both to below 52ksi. I’m only planning on running this round in a gas gun. For future reference, does anyone know if the notorious 6.5 Grendel bolt failure resulted in just a broken bolt or was it a catastrophic failure?
Similar threads
