New 6mm Advanced Rifle Cartridge

Gtscotty · Dec 20, 2024

Bantam1 said:
So what is the powder everyone seems to have settled on for the 108 grain loads? I am about ready to start loading for mine. I finally have depleted the factory ammo I bought for barrel break in and learning the platform a little more. I see AR comp for the 90ish grain loads. I am sitting on a full case of 108 ELDM to start load development.

With the factory Hornady 108 I am getting around 2670 for velocity with the 20" Proof barrel. If I can keep it around there I would be happy.

I think most folks are running LVR, especially if you are looking to match factory velocities. Other similar options would be CFE223 and AA2520. Personally my load with the 108gr is 29.3gr LVR, 450s, 20 thou off, matches up to the factory velocities fairly well, a little faster in warm temps. The 29.1gr to 29.5gr range for LVR has been a sweet spot for me across several bullets in the 95gr to 108gr weights.

Attached is some data Sierra sent me, doesn't include LVR, but has CFE223 which is similar, and for the 100gr and 110gr loads, matches up to Hornady data pretty well. The 107gr data is weirdly low compared to the two other weights bracketing it though.

LRRPF52 · Dec 21, 2024

Interesting video from Wade at Texas Predator Hunting. He was doing high pressure test in a pressure test rig, running things way above SAAMI, and finally experienced firing pin aperture erosion, flaking, causing FTFire, FTExtract.

Hasn’t had any issues with bolts under normal operation for years.

When I broke bolts in 5.56, I started having FTFeed, because the bolt cracked at the cam pin hole.

I’ve been shooting Grendel since 2009 across a wide variety of barrel and gas system lengths, tons of factory and hand loads, still haven’t broken a bolt or extractor.

I’ve been shooting the 12” CLGS Suppressed as my go-to since 2017, but I take the 17.6” Lilja and 18” LaRue along with it usually as well. Things just run.

putput30 · Dec 21, 2024

LRRPF52 said:
Interesting video from Wade at Texas Predator Hunting. He was doing high pressure test in a pressure test rig, running things way above SAAMI, and finally experienced firing pin aperture erosion, flaking, causing FTFire, FTExtract.

Hasn’t had any issues with bolts under normal operation for years.

When I broke bolts in 5.56, I started having FTFeed, because the bolt cracked at the cam pin hole.

I’ve been shooting Grendel since 2009 across a wide variety of barrel and gas system lengths, tons of factory and hand loads, still haven’t broken a bolt or extractor.

I’ve been shooting the 12” CLGS Suppressed as my go-to since 2017, but I take the 17.6” Lilja and 18” LaRue along with it usually as well. Things just run.

I saw that. I like how Wade is constantly pushing the arc to its maximum to see where it will fail so we don't have too. I want him to push a more exotic bolt like the geissele to its limit to see the differences between a standard vs exotic bolt material. Curious if the geissele platforms can be pushed to 62k or are they just like any other standard AR.

LRRPF52 · Dec 21, 2024

I’m not an advocate of chasing pressure to try to eek out marginal gains in performance.

I quickly learned to look at load manuals and find powders that generated top-end velocities, but with lower pressures. Let the powder do the work rather than trying to get brave on the bench.

Maybe that’s why I’ve never broken a Grendel bolt, but have velocities that are higher than factory ammo as a general rule, but 2500-5000psi less than SAAMI MAP.

Tex68w · Dec 22, 2024

6 ARC keeps getting it done.

Bantam1 · Dec 23, 2024

I have LVR and CFE along with other powders. I have been following this thread for a while. I'm going to start load workup soon and just wanted to double check here to see if any other powders were doing better. It's interesting to see the differences in data for Sierra and Hornady.

Thanks for the help.

Gtscotty · Dec 23, 2024

Tex68w said:
6 ARC keeps getting it done.

Both nice bucks, especially that 10 pt. What bullet(s) did you use?

Tex68w · Dec 23, 2024

Gtscotty said:
Both nice bucks, especially that 10 pt. What bullet(s) did you use?

Thanks! He's actually an 11, we have a left side kicker that comes off of the main beam in the genetics out there. I hate getting the odd number points but the genetics are improving for a hill country low fence property. The fat 6 was on my hit list this year since he lacks brow tines. I have been using factory loaded Hornady 108 ELD-M's.

Gtscotty · Dec 24, 2024

To tack on, it's been about a month back, but I tagged a buck and a doe with my 12.5" 6 ARC this year, about 30 minutes apart, using one of my hunting loads developed for my 18" ARC (103gr ELDx, 29.3gr LVR, 450s, 2.24"). Performance was quite good, first shot was a neck shot on the buck that dropped him and then a follow up to the heart from the bottom of the chest angled up the neck. The doe came in on the same trail about 30 minutes later and a shot at 60yds fragged her heart. The neck shot on the buck and the quartering shot on the doe exited.

I love the shorty ARC for close in hunting, It's so handy with a can. I put it together about a week before taking those deer and didn't have time to do specific load development for it, so that's coming up after the holidays.

Gtscotty · Dec 24, 2024

Bantam1 said:
I have LVR and CFE along with other powders. I have been following this thread for a while. I'm going to start load workup soon and just wanted to double check here to see if any other powders were doing better. It's interesting to see the differences in data for Sierra and Hornady.

Thanks for the help.

There is some variance between Hodgdon, Hornady and Sierra, none of them are highest or lowest across the board. Seating depth and bullet design are going to play a big part, the load difference within Sierra data between the 100gr TGK and SBT is a grain, probably due to bearing surface differences. Just like any other cartridge, you've gotta do the load work and with ARs, gotta make sure they are tuned well before putting anything in stone.

CFE223/bullet weight	95gr	100gr	103-105gr	107gr	108-110gr
Hodgdon	30.4	28.6	28.9	28.8	28.2
Hornady	29.4	29.4	28.6		29.1
Sierra	29.5	28.2-29.2		27.4	29.2

As a reference for LVR, here is what some of my load workups looked like in my 18" X-Caliber.

Factory loads.

Tex68w · Dec 24, 2024

Gtscotty said:
To tack on, it's been about a month back, but I tagged a buck and a doe with my 12.5" 6 ARC this year, about 30 minutes apart, using one of my hunting loads developed for my 18" ARC (103gr ELDx, 29.3gr LVR, 450s, 2.24"). Performance was quite good, first shot was a neck shot on the buck that dropped him and then a follow up to the heart from the bottom of the chest angled up the neck. The doe came in on the same trail about 30 minutes later and a shot at 60yds fragged her heart. The neck shot on the buck and the quartering shot on the doe exited.

View attachment 8576462
View attachment 8576460
View attachment 8576461

I love the shorty ARC for close in hunting, It's so handy with a can. I put it together about a week before taking those deer and didn't have time to do specific load development for it, so that's coming up after the holidays.

I am finding the shorty 6 ARC to be perfect for the field as well. After changing things up annually for the past few seasons I think I have my deer rifle for the next few years.

david walter · Dec 24, 2024

Haven’t had this anywhere but the range, but have it dialed in with 105 BTHP handloads and gassed right with the can.

Looking forward to bloodying it later this year.

Faxon Gunner 16”, AB Warthog 308 can. Timney trigger and Athlon 2-12 scope. The rest are
parts from other abandoned projects.

Balances nicely being held or on the tripod.

Jdowns0415 · Dec 26, 2024

Odinworks barrel shit the bed. I’ve had nothing but problems with it since purchasing it. Anyone use Shaw barrels? I’d like to replace it with one of theirs if they’re good. Trying to stay away from BA and ranier.

Rob01 · Dec 26, 2024

I got a Satern barrel on my Grendel Hunter upper and it’s an excellent barrel. Worth a look as they sell only barrels too.

6MM ARC Barrels | Grendel Hunter | The Modern Sporting Rifle

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Tex68w · Jan 6, 2025

Kill count this season.

(2) Whitetail Bucks
(2) Aoudad/Barbary
(2) Pigs

Reload10 · Jan 6, 2025

Tex68w said:
Kill count this season.

(2) Whitetail Bucks
(2) Aoudad/Barbary
(2) Pigs

Awesome. What bullet you using and what bubble level on the Reptilia mount? Pretty solid?

Tex68w · Jan 6, 2025

Reload10 said:
Awesome. What bullet you using and what bubble level on the Reptilia mount? Pretty solid?

Factory Hornady 108's. The level is nice, it's a recent offering from Reptilia. It doesn't stick out too far, easy to see in your peripheral.

BravoSector1 · Monday at 1:34 PM

Late season antlerless whitetail Nebraska hunt was a success. Tagged out and the 6ARC performed well. Very cold temps the first two mornings, -9F, so the deer were bedded down in the cedars and holding very tight. Specifics are below but both rounds were recovered just shy of hide on the other side of the animal. No bone was struck that we could see. Very light recoiling platform and a lot of fun. We dispatched a few coyotes as well (way too many out there this year) and deer numbers seem to be down compared to previous years.

Doe 1 shot at 117 yards broadside, vitals. Round 1 recovered below. Factory Hornady Precision Hunter 103 ELD-X met target at 2,357 fps and 1,270 ft lbs of energy. Recovered round weighed in at 73.1 gn with core/jacket separation. Walked 10 yards and expired.

Doe 2 shot at 187 yards broadside, vitals. Round 2 recovered below. Factory Hornady Precision Hunter 103 ELD-X met target at 2,236 fps and 1,143 ft lbs of energy. Recovered round was intact, nicely mushroomed, and weighed in at 75 gn. Walked about 20 yards and expired.

Round 1 recovered

Round 2 recovered

Tex68w · Monday at 5:58 PM

BravoSector1 said:
Late season antlerless whitetail Nebraska hunt was a success. Tagged out and the 6ARC performed well. Very cold temps the first two mornings, -9F, so the deer were bedded down in the cedars and holding very tight. Specifics are below but both rounds were recovered just shy of hide on the other side of the animal. No bone was struck that we could see. Very light recoiling platform and a lot of fun. We dispatched a few coyotes as well (way too many out there this year) and deer numbers seem to be down compared to previous years.

Doe 1 shot at 117 yards broadside, vitals. Round 1 recovered below. Factory Hornady Precision Hunter 103 ELD-X met target at 2,357 fps and 1,270 ft lbs of energy. Recovered round weighed in at 73.1 gn with core/jacket separation. Walked 10 yards and expired.

Doe 2 shot at 187 yards broadside, vitals. Round 2 recovered below. Factory Hornady Precision Hunter 103 ELD-X met target at 2,236 fps and 1,143 ft lbs of energy. Recovered round was intact, nicely mushroomed, and weighed in at 75 gn. Walked about 20 yards and expired.

View attachment 8591064
View attachment 8591065

Round 1 recovered
View attachment 8591068

Round 2 recovered
View attachment 8591070

Great feedback with the recovered rounds and retained weight.

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