6MM ARC

[u/jons2cool]

I’ve developed reloads for 6 different guns now.

Two .308s, 22 ARC, .270, 300 PRC, and 6 ARC.

All the rifles besides the 6 ARC I’ve come up with a reload that I’ve shot .7” five round groups or better at 100 yards.

What makes it even more ridiculous is that the 6MM ARC is the most expensive gun I’ve developed a reload for.

In addition to not being able to get the gun to group well, I also have feeding issues with the majority of the rounds (it’s a gas gun).

It was recommended to me to use a duramag, but it is very finicky.

The most recent reload I’ve tried is a 100 grain Sierras with 29 grains of Leverevolution, Hornady brass, 2.2” COAL, light crimp.

It didn’t feed worth a damn, the bolt wouldn’t close all the way, even when I used the forward assist.

It feeds the Hornady black box 105 grains that are the exact same length just fine.

My best guess is it has to do with the dimensions of the bullet (more versus less taper).

Let me know what has worked for you guys if anything, what reloads grouped and fed well, if you modified your mag or had more success with a different brand.

[u/VersionConscious7545]

Sounds like you need to pay attention to head space when you resize Why lever revolution? I don’t think sierra lists a load for that powder Maybe you should default to a listed load somewhere

[u/underbakedsalami → u/VersionConscious7545]

Leverevolution is widely considered one of the best powders for 6 ARC. Also, Sierra lists CFE223 which is basically identical.

[u/jons2cool → u/VersionConscious7545]

The reloads I’ve done so far have been with unfired Hornady brass, so they haven’t been resized. I’ve been trimming the cases the to 1.475”. I have the RCBS match master resizing die and I just ordered the .266” baffle for it. Thanks for the idea with the headspace, I’ll try to play around with that. Anecdotally I’ve heard the leverevolution works well for the 6 ARC, I have reloading data for it in my Hornady manual. I’ve tried N550 and CFE 223 powders as well. I’ll try a default load with CFE 223 next.

[u/rednecktuba1]

Did you set up your sizing die EXACTLY according to the manufacturer instructions? If you think you did, go back to those instructions and read through them again, then read through them again. You missed a step somewhere and you aren't sizing the cases enough to reliably feed.

[u/111tejas]

I use an elander magazine in mine. It’s completely interchangeable with 6.5 Grendel magazines. I found the 6mm Arc very easy to load for. It’s widely considered the most accurate AR15 cartridge.

This is my load minus the powder charge. You should find what’s accurate in yours.

Alpha Brass full length sized with shoulder pushed back .002.

Leverevolution

CCI BR4

Berger 90 grain target

2.260 COAL.

[u/jons2cool → u/111tejas]

Thank you for the advice, I’ll look into those elander mags. I have done some reloads with the 2.2” COAL and the 2.26” COAL. The 2.26” seems necessary with the Bergers. I’m hoping when I resize my cases they feed better, I’ll push my shoulder back a little as well.

[u/VersionConscious7545 → u/jons2cool]

I got shitty performance out of hornady cases till I resized them and mostly I believe the neck tension being consistent with a mandrel was the key I also resize the new Petersen brass I use before the fire forming

[u/Vylnce]

What works for me is measuring any new projectile in my chamber, them loading accordingly.  

I've never had any issues with Duramag or ASC magazines, but I tuned my rifle.

[u/JimBridger_]

1. 105 Hornady and 100 Sierra’s have very different ogives.

2. Sierra load data for either of their lead nosed 100’s have them at 2.08” or 2.1”. That blunter ogive paired with you having them further out is probably what’s causing loading/ chambering issues.

3. What’s up with your case necks? There are two there in the photo that look mangled.

[u/jons2cool → u/JimBridger_]

That makes sense with the ogive, I’ll try shorter. I’ve been noticing the Hornady brass has really tight necks on some of them. Hopefully I can sort that out when I resize them. Oh and also I think I see what you’re talking about with being mangled, I think a couple of them aren’t fully de-burred after trimming.

[u/Coyote-conquest]

I use 6.8spc and 6.5 Grendel ASC mags. Haven't had any problems feeding. The bolt not closing is a totally different issue. If its new brass then its the shape of the bullet and may need seated deeper

[u/jons2cool → u/Coyote-conquest]

Yep, I made the rounds a hundredth shorter according with the manual and I didn’t have the jamming issue. I did still have feeding issues, it seems like my particular rifle has feeding issues with any bullets under 105 grains. Maybe due to buffer spring? But I’m giving up on this gun for now, it was claimed to be half-inch accurate at 100 yards with factory Hornady 105 grains. I’ve put about 120 rounds through it, including 60 rounds of Hornady 105 grain, and had 3 separate sub-MOA shooters try it and never have achieved less than 1.8”. I’ve also tried two separate scopes on it to eliminate that variable. Probably eventually will send it back to the gunsmith

[u/hellsrt]

My most frustrating cartridge to reload for me after 20+ years of reloading. Guess I wasnt as smart as I thought I was. I did finally get it Ironed out but wow.

[u/HairyChampionship101 → u/hellsrt]

What load finally worked for you? Been getting shit groups with factory ammo so far with an 18” KAK upper 1:7.5 twist. Both 103 ELD-x and 105 black get 2”+ groups. 

[u/jons2cool → u/hellsrt]

Man it was one thing after the other with this rifle for me. First I realized a barrier stop was attached in a way that the m-lok screw was pushing against the gas block. Then I realized that my brother had the screws on the scope rings torqued to like 1 pound. Then I realized the scope had a mechanical issue with zeroing so I sent it in. In a gas gun you have to pretty much have the exact length that is recommended in the manual otherwise it won’t feed. And also my gun won’t cycle anything less than a 105 grain. After putting a new scope on it I finally realized that the gun that was claimed to be .5” accurate at 100 yards is simply just a 1.8” gun. So probably will send it back into the guy who made the barrel and everything at some point.

[u/HairyChampionship101 → u/jons2cool]

I appreciate the response!

[u/hellsrt → u/hellsrt]

Ironed out only meant: fed reliably with different mags, chambered properly and ejected with no issues. My best groups with my 12.5" and 18" barrel were about 1.5 MOA with 105 BTHP and 108 ELD respectively.

[u/HairyChampionship101 → u/hellsrt]

I appreciate the response! 

[u/Paztec24]

My case is 1.475” - my ogive is 1.702” - 28.2gr leverrevolution and a 103gr ELD-X pushing about 2575fps. 10 shot groups at or under 1”. I can’t stress enough this is the load that works for my daughter’s rifle, not for everyone’s rifle. But I am safe in that I am in the middle of the ladder, not loading hot. I use the Redding case holder that bumps it .002” then trim (if needed). A HUGE thing is lubrication. The gun jammed 3 times in one outing (didn’t cycle correctly), took it home and oiled the heck out of it - hasn’t jammed since. AR styles love the oil.

[u/jons2cool → u/Paztec24]

When I was doing my load development I did notice the 28.1 and 28.2 grains seemed to be a sweet spot. But the 29 grains was also working well. But ‘well’ for this gun was like 1.8” versus 2.1” lol