New 6mm Advanced Rifle Cartridge

running various loads (low to high) out of my odinworks 18 inch rifle gas barrel with their gas block and BCG...getting belts on the cases with starline brass and even hornady factory ammo. Shooting sub MOA 10 shot groups but when I try and resize the case that belt gets so big it looks like a 300 winmag case does. Consulting the hide because I dont want to have to single feed my 6arc. The belts started appearing with lvr loads, my varget loads seemed to be ok, they were 26.7 with a 108 ELDM/Berget BT Target and 29.7 with the new ELDVT. Using CCI 450 primers. the lvr loads showed pressure with just 29.4gr and were already running 100fps higher than hornady's book velocity so I abandoned it for the summertime here in Texas as I know we are about to hit 90 days of temps above 100 and the sun will be blazing in the cloudless sky. Thanks for all the help this thread has given me so far.
 
For a AR15 bore guide, I use the Bore Tech Bore Guide..... Works great!

 
Shit pic I know, but it's what I've got. I am still waiting on a few more items to further fine tune the build (trigger, grip, optic level), but other than she's pretty much done. I might throw the Acro back on top after my next range trip. I thought about moving to a shorter and lighter suppressor but this thing will live at the range in prone or from a tripod so I don't really see the point in the change if it's working reliably. I still love the look of the SDN-6, such a timeless can IMHO.


4R5r9p7.jpg
 
running various loads (low to high) out of my odinworks 18 inch rifle gas barrel with their gas block and BCG...getting belts on the cases with starline brass and even hornady factory ammo. Shooting sub MOA 10 shot groups but when I try and resize the case that belt gets so big it looks like a 300 winmag case does. Consulting the hide because I dont want to have to single feed my 6arc. The belts started appearing with lvr loads, my varget loads seemed to be ok, they were 26.7 with a 108 ELDM/Berget BT Target and 29.7 with the new ELDVT. Using CCI 450 primers. the lvr loads showed pressure with just 29.4gr and were already running 100fps higher than hornady's book velocity so I abandoned it for the summertime here in Texas as I know we are about to hit 90 days of temps above 100 and the sun will be blazing in the cloudless sky. Thanks for all the help this thread has given me so far.
Do you have the wrong bolt by any chance?
 
  • Like
Reactions: rpoL98
At 13.5lbs its finally ready to rock! I'm taking Thursday off from work for a range trip and barrel break in.View attachment 8440041

Weight adds up so fast my 20” gun is 9.8lbs. My heaviest accessory is my scope. It is 26.5 ounces without the mount. After adding my suppressor, and bipod, and A5 rifle stock. It’s only gonna get chonkier lol.
 

Attachments

  • IMG_3714.jpeg
    IMG_3714.jpeg
    294.7 KB · Views: 51
I ran out of time at the range with prioritizing breaking in my 300blk. But I did get the 1st 3 rounds of hornady 108gr factory ammo down the 24" xcaliber barrel and chronographed. I sure hope it speeds up as it breaks in.
 

Attachments

  • Screenshot_20240620_172111_ShotView.jpg
    Screenshot_20240620_172111_ShotView.jpg
    128.9 KB · Views: 26
  • Like
Reactions: tex68w
Weight adds up so fast my 20” gun is 9.8lbs. My heaviest accessory is my scope. It is 26.5 ounces without the mount. After adding my suppressor, and bipod, and A5 rifle stock. It’s only gonna get chonkier lol.

My 18" with can and an empty mag came to 11lbs 7oz, definitely not a lightweight. That said, the can is a SDN-6 which is long and heavy, B5 Precision stock is heavy, NF ATACR 4-16X isn't light and the LMT monolithic upper and barrel system aren't exactly light either.
 
Last edited:
no its a 6.5 grendel type 2 from odinworks, it came with the barrel.
OdinWorks are pretty good on customer service, from my experience. I had headspace issues with a Toolcraft 6.5 G Type 2 bolt in OW's 20" DMR 6.5 G barrel. Sent them the barrel, bolt, Manson gauges used. They sorted it out and gave me a full BCG (not just a bolt) because of the several weeks it took them. They were also pretty good about discussing powders & projectiles for their barrels.
 
My 18" with can and an empty mag came to 11lbs 7oz, definitely not a lightweight. That said, the can is a SDN-6 which is long and heavy, B5 Precision stock is heavy, NF ATACR 4-16X is light and the LMT monolithic upper and barrel system aren't exactly light either.

Very nice! I’m running a ‘CMMG Resolute 100’ 20” 6MM arc upper, and PSA carbine lower. It is pretty light weight, but I think that’s from the pencil barrel. Glass is Steiner M8Xi 1-8 with Reptilla Aus 34MM mount, suppressor is a OCL Polonium (in jail) I still haven’t ordered a freakin bipod 😞 I honestly cannot decide between Atlas BT46LW17 or Accutac BR4G2, or maybe even the TBAC bipod but the TBAC is kind of pricey. I literally cannot decide though. I like them all.
 
  • Like
Reactions: tex68w
Very nice! I’m running a ‘CMMG Resolute 100’ 20” 6MM arc upper, and PSA carbine lower. It is pretty light weight, but I think that’s from the pencil barrel. Glass is Steiner M8Xi 1-8 with Reptilla Aus 34MM mount, suppressor is a OCL Polonium (in jail) I still haven’t ordered a freakin bipod 😞 I honestly cannot decide between Atlas BT46LW17 or Accutac BR4G2, or maybe even the TBAC bipod but the TBAC is kind of pricey. I literally cannot decide though. I like them all.

I’ve had all of them, I am partial to the TBAC but they are all GTG.
 
running various loads (low to high) out of my odinworks 18 inch rifle gas barrel with their gas block and BCG...getting belts on the cases with starline brass and even hornady factory ammo. Shooting sub MOA 10 shot groups but when I try and resize the case that belt gets so big it looks like a 300 winmag case does. Consulting the hide because I dont want to have to single feed my 6arc. The belts started appearing with lvr loads, my varget loads seemed to be ok, they were 26.7 with a 108 ELDM/Berget BT Target and 29.7 with the new ELDVT. Using CCI 450 primers. the lvr loads showed pressure with just 29.4gr and were already running 100fps higher than hornady's book velocity so I abandoned it for the summertime here in Texas as I know we are about to hit 90 days of temps above 100 and the sun will be blazing in the cloudless sky. Thanks for all the help this thread has given me so far.
This should help

As would getting a sizing die that's a little bigger, early Hornady dies were pretty small, I forget which ones SOA says are best but they have a video somewhere on it.
 
Laid up and recovering from surgery but this is my almost complete 6ARC. Just waiting on the NF ATACR 4-16 to top it off.

View attachment 8446454

Seekins Receivers | Seekins Handguard | Proof Research 18" 6ARC | OCL Polonium | NF 34mm Mount | Geissele SD-E | Magpul PRS Gen 3 | Atlas Bipod
beautiful. let me know how that polonium does on there I am interested in getting one myself.
 
I found a few hours today upon returning home to get to the range. Factory loaded Hornady 108 ELD-M's did great, this is the best group yet from the rifle out of every factory Hornady load it has seen (80 ELD-VT, 103 ELD-X, 108 ELD-M). I forgot to bring the chrono once again so I don't have any numbers there.

I sighted the rifle in to be 1.8-2" high at 100 yards for a 200 yard zero. The final 5-round group with the 108 ELD-M's printed a 0.498" group. For a factory load from a gas gun I couldn't be more pleased and I still don't have a light pull match trigger in the rifle yet so I have to believe it can do even better. I am sitting at roughly 100-120 rounds down the tube on this setup so I expect things to get better in the next few hundred rounds as well.

I wasn't sure about the Ecco Machine HUB converted AAC SDN-6 on this rifle at first, thinking I needed to have a back pressure reducing can like most everyone says but so far the recoil is light, gas to the face is minimal and it tosses the brass 4-5 feet at 3:30-4 o'clock. I believe I'll keep it as is for now.

dTLPrtD.jpg

8WsErtU.jpg
 
I found a few hours today upon returning home to get to the range. Factory loaded Hornady 108 ELD-M's did great, this is the best group yet from the rifle out of every factory Hornady load it has seen (80 ELD-VT, 103 ELD-X, 108 ELD-M). I forgot to bring the chrono once again so I don't have any numbers there.

I sighted the rifle in to be 1.8-2" high at 100 yards for a 200 yard zero. The final 5-round group with the 108 ELD-M's printed a 0.498" group. For a factory load from a gas gun I couldn't be more pleased and I still don't have a light pull match trigger in the rifle yet so I have to believe it can do even better. I am sitting at roughly 100-120 rounds down the tube on this setup so I expect things to get better in the next few hundred rounds as well.

I wasn't sure about the Ecco Machine HUB converted AAC SDN-6 on this rifle at first, thinking I needed to have a back pressure reducing can like most everyone says but so far the recoil is light, gas to the face is minimal and it tosses the brass 4-5 feet at 3:30-4 o'clock. I believe I'll keep it as is for now.

dTLPrtD.jpg

8WsErtU.jpg
Good shooting man. I have one of the Dwilson 16" proof conversions and it shoots 108's like that. VERY good setup. Wasn't sure I would like 6arc, but I do.

Oddly, I'm running a 1-10 on mine (vtx razor) and its pretty good for this gun. 12 mils of drop in reticle gets me to 1000 up here.

IMG_2235.jpeg
image_cropper_A8AEB257-0C49-44E6-BAC7-3DCEB10C4E5B-8537-00001C888747CEBD.jpeg
 
Last edited:
Good shooting man. I have one of the Dwilson 16" proof conversions and it shoots 108's like that. VERY good setup. Wasn't sure I would like 6arc, but I do.

Oddly, I'm running a 1-10 on mine (vtx razor) and its pretty good for this gun. 12 mils of drop in reticle gets me to 1000 up here.

View attachment 8448236View attachment 8448238


Same, I have really come to appreciate the 6 ARC. Mine will shoot the factory loaded 80 VT's at .5-75 MOA as well. I've only run one box of 103 ELD-X through it and while it was sub-moa it was the worst performer of the three. Now that I have a proper trigger in the gun I plan to go back and get good data on all three and shoot for the best groups I myself can produce. With the 18" barrel and factory 108's I am around 10.5-11 MIILS to 1000.
 
Last edited:
My only real need for the 103 would be for killing, possibly whitetail in particular. With the new trigger I imagine I'll be able to shrink my groups some and if I can get consistent 3/4" groups from it with the 103's then I'll be more than happy to use it for deer hunting.
 
Last edited:
Good shooting man. I have one of the Dwilson 16" proof conversions and it shoots 108's like that. VERY good setup. Wasn't sure I would like 6arc, but I do.

Oddly, I'm running a 1-10 on mine (vtx razor) and its pretty good for this gun. 12 mils of drop in reticle gets me to 1000 up here.

View attachment 8448236View attachment 8448238
I had thought about that scope but the lack of parallax adjustment made me hesitant
 
My only real need for the 103 would be for killing, possibly whitetail in particular. With the new trigger I imagine I'll be able to shrink my groups some and if I can get consistent 3/4" groups from it with the 103's then I'll be more than happy to use it for deer hunting.
The 103 in 6 ARC worked fine on whitetail this past season for me. Complete pass through, no recovered bullet, close range though, like 20 yds.
 
Did they kick you out of the Petting Zoo?
lol

Two deer must have winded my buddy on the other side of the property and sprinted basically directly at me. I wasn't really desperate for a deer (just finished processing my elk) but if they insisted...

Just to try different things out, I'll likely hunt with 106 TAP or a monolithic this year.
 
Last edited:
That's some damn good velocity but to be expected with that long pipe. I am surprised to see that most don't get the 80's to group 1 moa or better.
 
I’ll have to try loading the 80’s since my gun didn’t like the factory stuff.

My coyote load right now is the 75 vmax over TAC at about 3015 fps which gives me point and shoot to almost 300y. This talk about the 103’s has me thinking I should try those too and may stock those instead of the 108’s
 
  • Like
Reactions: tex68w
I’ll have to try loading the 80’s since my gun didn’t like the factory stuff.

My coyote load right now is the 75 vmax over TAC at about 3015 fps which gives me point and shoot to almost 300y. This talk about the 103’s has me thinking I should try those too and may stock those instead of the 108’s


My rifle doesn't like the 103's as much as the 108's and 80's. I plan to get out again soon now that I have a better trigger in the gun and see if I can't tighten things up with all three. The 80's are cool but I don't see myself shooting them that often going forward. If I can get the 103's to 3/4" or better I'll likely use them for hunting and keep the 108's for steel but I have no problem using the 108's for everything, I just wish they were a little faster.
 
  • Like
Reactions: rlsmith1
I wanted something new to play with in the AR world. I've resisted but said WTH lets play with 6 ARC and see how it does.

Heres what I decided to build. Had almost all these parts laying around. Got the barrel for under $350 and had to grab a RCA 6.5 Grendel bolt. I already had a RCA 5.56 BCG new sitting in a box.

22" Rainier Ultramatch MOD2 6 ARC +2 Gas
Rubber City Armory BCG with AGK
MEGA Billet AMBI lower
MEGA SBU Thick Walled Billet Upper Receiver
Geissele Super Braided 42 and H1 Buffer
Geissele Premium Mil-Spec Buffer Tube
LaRue Tactical MBT-2S Straight Bow Trigger w/JP Spring
Battle Arms Development Ambi Safety
Magpul PRS Lite
250pcs Starline brass
Geissele 15" MK14 Handguard


I would like to run lighter bullets fast and lights out accurate in the 60-80gr range but we will see what this barrel likes.
 
I wanted something new to play with in the AR world. I've resisted but said WTH lets play with 6 ARC and see how it does.

Heres what I decided to build. Had almost all these parts laying around. Got the barrel for under $350 and had to grab a RCA 6.5 Grendel bolt. I already had a RCA 5.56 BCG new sitting in a box.

22" Rainier Ultramatch MOD2 6 ARC +2 Gas
Rubber City Armory BCG with AGK
MEGA Billet AMBI lower
MEGA SBU Thick Walled Billet Upper Receiver
Geissele Super Braided 42 and H1 Buffer
Geissele Premium Mil-Spec Buffer Tube
LaRue Tactical MBT-2S Straight Bow Trigger w/JP Spring
Battle Arms Development Ambi Safety
Magpul PRS Lite
250pcs Starline brass
Geissele 15" MK14 Handguard


I would like to run lighter bullets fast and lights out accurate in the 60-80gr range but we will see what this barrel likes.

Sounds like a solid build. So far the 80's don't appear to be doing too well in most rifles, mine is an exception.
 
When my RTR barrel gets here I'm going to start my testing with the following bullets. If they don't hammer I have 95 TMKs I'll try before moving to 100+gr bullets.

Hornady 75 VMAX
Hornady 87 VMAX
Hornady 87 BTHP
Sierra 85 BTHP GameKing
Berger 88 Flat Base Match
 
Last edited:
When my RTR barrel gets here I'm going to start my testing with the following bullets. If they don't hammer I have 95 TMKs I'll try before moving to 100+gr bullets.

Hornady 75 VMAX
Hornady 87 VMAX
Hornady 87 BTHP
Sierra 85 BTHP GameKing
Berger 88 Flat Base Match
My previous 22" Rainier barrel loved Berger 95 VLD target @2920ish with Lever. Those were the tightest groups with that barrel. Despite the VLD rep for being finicky, they just agreed with the ARC chamber & feed geometry.

I think feed geometry is an overlooked Achilles heel in this caliber on AR's. The Berger 109's tip hit the feed cone in the barrel before the case shoulder hit/lifted on the ramp. Been thinking about making a stepped mag catch to raise the mag a little, .030" is about all it needs.

I suspect the RTR will be very very similar as for the chamber.

Just ordered a 22" RTR since Rainier #2 appears to be smashing lugs again.

Also have a 18" Centurion RL + 1" 6 ARC sitting on the shelf with a pile of Geissele parts.
 
  • Like
Reactions: rpoL98
My previous 22" Rainier barrel loved Berger 95 VLD target @2920ish with Lever. Those were the tightest groups with that barrel. Despite the VLD rep for being finicky, they just agreed with the ARC chamber & feed geometry.

I think feed geometry is an overlooked Achilles heel in this caliber on AR's. The Berger 109's tip hit the feed cone in the barrel before the case shoulder hit/lifted on the ramp. Been thinking about making a stepped mag catch to raise the mag a little, .030" is about all it needs.

I suspect the RTR will be very very similar as for the chamber.

Just ordered a 22" RTR since Rainier #2 appears to be smashing lugs again.

Also have a 18" Centurion RL + 1" 6 ARC sitting on the shelf with a pile of Geissele parts.

Can you expand on the bolded sentence any? What exactly is happening and is it happening to the bolt lugs or the receiver extension? Sounds like maybe it's not the first Ranier barrel to have issues?
 
Last edited: