6mm ARC in AR platform Loading Advice?

[Jr solocam]

I bought an APF AR in 6mm ARC.

I have reloaded my bolt rifles for many years.

In a nutshell what do I have to consider when loading for an AR? Just some basic things I am looking for. Thank you for your advice.

 

[Dan-Schenk]

Typically, there needs to be a little more shoulder bump. You may/may not need a small base die. Also pressure needs to be lower.

 

[Straightshooter1]

I bought an APF AR in 6mm ARC.

I have reloaded my bolt rifles for many years.

In a nutshell what do I have to consider when loading for an AR? Just some basic things I am looking for. Thank you for your advice.

Yup. . . more shoulder bump (as mentioned) and probably a little more neck tension. And maybe need to use primers that have thicker cups (like, not CCI-400's ).

 

[EGBrown]

I found it extremely helpful to purchase a case gauge so that I could verify each round would chamber easily.
An AR-platform is not as forgiving as a bolt action.

I use a Lyman orange ammo checker

 

[Retired shooter]

When choosing powder charge be sure you are looking at grains for AR. All the load manuals I have seen list load data for AR, and Bolt Rifle

 

[David Milisock]

I bought an APF AR in 6mm ARC.

I have reloaded my bolt rifles for many years.

In a nutshell what do I have to consider when loading for an AR? Just some basic things I am looking for. Thank you for your advice.

I've been reloading for a factory Colt HBAR AR15 A2 in 5.56 x 45 for over 3 decades and I do very little different then what I do for my medium game bolts. Full length size, trim properly, because of the gas system stick to a powder in the burn rate and projectile weight that the rifle was designed for.

I use a chronograph! With hand loads using Varget and I believe 68 or 69 grain Hornady match with the rifle in Delta configuration it regularly does better than 2" groups at 200 yards and makes hits at 500 yard IPSC 9" x 15" steel if the wind grants me permission. It shoots OK with XM193 and worse with XM855

What I'm changing for the 6MM ARC VS the 5.56 is that I'm upping my powder weighing game with digital scales as the mechanical structure of the 6MM ARC bolt is more sensitive to pressure variations. I'm also sticking to 52,000 PSI gas rifle loads, 103 ELDX projectiles and a powder with a slower pressure curve, LeverEvolution. The design was originally for 103+ grain projectiles, (108 ELDM).

My 6MM ARC AR is a general purpose rifle, I'm settling on one load and carrying it.

 

[Larry Koch]

Load until the bolt breaks and thats the high limit. Back off from there.

 

[ZenArchery]

Hornady actually has a different load charge for the 6ARC AR vs Bolt. Start low and work up. You’ll be limited 2.260-90” (depending on magazine) with long 85gr+ bullets.

 

[GWY]

Load until the bolt breaks and thats the high limit. Back off from there.

Agreed. There isn't a lot of steel on a 6 Grendal AR around the case's head on the bolt face, unlike a 223 AR. Not uncommon for a bolt lug to break (usually the one near the extractor) from too many hot loads.

 

[David Milisock]

Agreed. There isn't a lot of steel on a 6 Grendal AR around the case's head on the bolt face, unlike a 223 AR. Not uncommon for a bolt lug to break (usually the one near the extractor) from too many hot loads.

From my experiance I have never read about or seen a bolt break in a Grendel or 6 ARC that (if I could get all the information) couldn't be traced back to something being done by the loader.

I talked to one guy who swore a factory round caused a bolt break. Only problem was that the rifle had several hundred rounds of a tad over max loads fired in it before that factory round was fired.

The problem with the AR platform is that anything with an opposable thumb is building rifles.

 

[Steve Donlon]

I have thought about a 6mm ARC but after reading this it sounds again like people trying to make a AR 15 do things it should not be asked to do. Why not a 6mm Creedmoor. Better in every way. Having more weight is a good thing IMO. That thing about the bolt breaking and less velocity and no heavy bullets is a deal breaker for me. But I have a 300 BLK to shoot like a M1 Carbine with 125 gr. bullets. No suppressed shooting, so I just see things different.

 

[CJ6]

Too many people trying to get bolt gun velocity out of a gas gun. AFAIK ALL factory loads are made specifically for ARs. (lower pressure).

 

[Retired shooter]

Too many people trying to get bolt gun velocity out of a gas gun. AFAIK ALL factory loads are made specifically for ARs. (lower pressure).

I was looking for something a little bit bigger than .223. Talked to Bartlein barrel, they referred me to a well known manufacturer, he talked me into 6ARC. Built me a complete upper assy, to pin onto a Rock river R3 comp. Lwr.
I am doing the opposite of everyone shooting the light weight projectile. Loading and using 110 A tips, and Leverevolution I am having very good experience. 2750 fps, and extremely good accuracy Currently 350 rounds down the tube, have shot 1200 yards out to one mile with good success. Currently working on loads for Berger 109, and Sierra 110s, looking for different, and or similar results. Ma y even try Barts 115 grain but I suspect they may to heavy, I being on retired budget do not agree loading tiill somethigg..... brakes.
I believe th 6 Arc is getting,into bad rap, I single load mine so cartridge length is not limited to magazine length Verry happy wit results .
Later

 

[The boogalorian]

I built a 6 arc shortly after the factory ammo was out. Have been hand loading since I emptied the factory ammo. The best advice I can give is know it has limits in a ar platform. If you are inclined to push a cartridge to its limit then I wouldn’t recommend a 6 arc in a ar. I like my 6 arc ar. It is a good shooter but it has limitations.

 

[David Milisock]

I have thought about a 6mm ARC but after reading this it sounds again like people trying to make a AR 15 do things it should not be asked to do. Why not a 6mm Creedmoor. Better in every way. Having more weight is a good thing IMO. That thing about the bolt breaking and less velocity and no heavy bullets is a deal breaker for me. But I have a 300 BLK to shoot like a M1 Carbine with 125 gr. bullets. No suppressed shooting, so I just see things different.

I thought about a 300 but I have 30 Carbines and 7.62 x 39's. I went with the 6MM ARC because I'm using it as designed, I'm loading 103 ELDX only. I've been shooting Hornady 105 factory for brass and I have some factory 103 Hornady as my control for loading. Using LeverEvolution powder as it's slower and more closely matches factory.

I did order a digital powder scale to improve the consistency of my charges and all my brass are once fired from the same lot of factory Hornady. Even if I only shoot factory 103 ELDX the rifle and cartridge performs exactly as I expected, except the accuracy was better than expected.

As far as a 6MM varmint I've been shooting a 6MM Remington in a 700 Remington for well over 3 decades. A 6MM Creedmoor in a bolt rifle might be OK but I'm not dumping my Remington for a 6MM with lesser case capacity.

 

[David Milisock]

I was looking for something a little bit bigger than .223. Talked to Bartlein barrel, they referred me to a well known manufacturer, he talked me into 6ARC. Built me a complete upper assy, to pin onto a Rock river R3 comp. Lwr.
I am doing the opposite of everyone shooting the light weight projectile. Loading and using 110 A tips, and Leverevolution I am having very good experience. 2750 fps, and extremely good accuracy Currently 350 rounds down the tube, have shot 1200 yards out to one mile with good success. Currently working on loads for Berger 109, and Sierra 110s, looking for different, and or similar results. Ma y even try Barts 115 grain but I suspect they may to heavy, I being on retired budget do not agree loading tiill somethigg..... brakes.
I believe th 6 Arc is getting,into bad rap, I single load mine so cartridge length is not limited to magazine length Verry happy wit results .
Later

Sounds interesting, I'm a bit more old fashioned, I use mine much closer to the intended design.

 

[David Milisock]

I built a 6 arc shortly after the factory ammo was out. Have been hand loading since I emptied the factory ammo. The best advice I can give is know it has limits in a ar platform. If you are inclined to push a cartridge to its limit then I wouldn’t recommend a 6 arc in a ar. I like my 6 arc ar. It is a good shooter but it has limitations.

Don't we all have our limitations!

 

[GetReal]

I'm consistently getting less than half moa from a 20" Bartlein in a AR semi platform with 90 (2875 fps) and 105 (2640 fps in a light load) Bergers using 450 CCI primers and LVR powder (its fairly dirty) . I started by converting 6.5 Grendel brass but now use Starline as well.

I throw individual charges from my RCBS Chargemaster and seat bullets using LE Wilson chamber type seating dies.

I do brass prep same as my bolt guns - shoulder bump, bushing style sizing dies, annealing, etc.

 

[Steve Donlon]

I thought about a 300 but I have 30 Carbines and 7.62 x 39's. I went with the 6MM ARC because I'm using it as designed, I'm loading 103 ELDX only. I've been shooting Hornady 105 factory for brass and I have some factory 103 Hornady as my control for loading. Using LeverEvolution powder as it's slower and more closely matches factory.

I did order a digital powder scale to improve the consistency of my charges and all my brass are once fired from the same lot of factory Hornady. Even if I only shoot factory 103 ELDX the rifle and cartridge performs exactly as I expected, except the accuracy was better than expected.

As far as a 6MM varmint I've been shooting a 6MM Remington in a 700 Remington for well over 3 decades. A 6MM Creedmoor in a bolt rifle might be OK but I'm not dumping my Remington for a 6MM with lesser case capacity.

Sounds like you know what you are doing. I treat every rifle I shoot like a bench rest rifle. I load all my AR platform rifles using my old Rock Crusher and a seat my bullets with a Redding Compition Seating die. Weigh all my loads. try different primers for each load. The #400 work best in many cases. Check every result at every step. I was amazed at the accuracy I am able to get with the right bullet from my DDM4 Hunter 300 BLK. That is why I used it as an example. Very easy to clean with 296 powder and no worries about pressure with any load. 300 yards is my range I shoot and it is very accurate at that range and effective. In my situation if I need to shoot beyond 300 yards, I'll use a bolt gun. I shoot my 223 out to 800 yards for fun but just targets. It seems like the Redding Competition Seating die eliminates runout which really helps. I use it in my 223 DDM4 V7 Pro with a 18 inch barrel. Same thing, 1" groups at 300 yards with the right bullet.

 

[David Milisock]

Sounds like you know what you are doing. I treat every rifle I shoot like a bench rest rifle. I load all my AR platform rifles using my old Rock Crusher and a seat my bullets with a Redding Compition Seating die. Weigh all my loads. try different primers for each load. The #400 work best in many cases. Check every result at every step. I was amazed at the accuracy I am able to get with the right bullet from my DDM4 Hunter 300 BLK. That is why I used it as an example. Very easy to clean with 296 powder and no worries about pressure with any load. 300 yards is my range I shoot and it is very accurate at that range and effective. In my situation if I need to shoot beyond 300 yards, I'll use a bolt gun. I shoot my 223 out to 800 yards for fun but just targets. It seems like the Redding Competition Seating die eliminates runout which really helps. I use it in my 223 DDM4 V7 Pro with a 18 inch barrel. Same thing, 1" groups at 300 yards with the right bullet.

I wanted to change to a digital scale for the 6ARC loads because of the lack of head room on max pressure compared to my other gas guns and my bolts.

With a balance beam the angle of viewing the scale is critical and I don't need a 1 to 2/10th error in charge weight. In my opinion the 6ARC in an AR needs to be loaded very near the 52,000 PSI max. In a 16" barrel I'm only going after 2,550 FPS which is very near WHT factory rounds clock in my rifle. This makes the 6ARC trajectory about the same as my 20" A2 in 5.56 with match grade projectiles but the 6ARC is a better than 60% improvement in wind and twice the energy at max effective 5.56 ranges and continues to be effective for a few more hundred yards.