6mm ARC for 1k yards build

[thedude824]

It’s been two years since I posted “I don’t see the allure of 6mm ARC”. I see the allure now. My collection is rather small but everything has a specific purpose (other than my 16” carbine gas Colt LE6920 with the MIL/LE restricted markings). I’m not really a fan, but can’t part with it or change it. I want to build another AR and I don’t have anything that is semi automatic AND ACCURATE past 1k yards. I’ve got a 16” 308 barrel for my SCAR 17, but it stays in the 13” configuration. My 14.5” piston AR definitely isn’t coming close to 1k. My MRAD especially in 338 is certainly capable, but a low recoiling AR would be so much fun. I know nothing about the caliber or who makes the best parts. So far I was thinking
Final build:
San Tan tactical receiver set
Geissele 15” MK4 rail
Craddock 18” RTR 6.5 Grendel barrel
Superlative Arms piston kit
POF roller cam pin
Geissele SDE 2 stage trigger
Magpul ACS with BCM MK2 buffer
JP enterprises rifle length spring
Fortis K2 endplate
Radian Raptor SD charging handle
Radian Talon safety
NightForce NX8 2.5-20 in an ADM mount
HUXWRX flash hider
Atlas V8 bipod
I was going to use a HUXWRW flash hider and use my Flow Ti 762 and maybe get the Flow 6mm if I end up really liking it and want to keep a can on it.
It looks like Duramag are the preferred mags? My main concern is that it has to be 100% reliable.. are the mags there yet? I’m not too concerned with weight since it will absolutely be lighter than my MRAD. I get a pretty nice discount on ADM and NightForce products as well as Proof.. so it seem like going with them was a no brainer. The entire setup will run about $4350. Id also REALLY like to find a refurbished PVS30 to use on a couple of these. Anyone see any glaring problems? Suggestions? Could I go 18” barrel and a 15” handgaurd and be good to 1k?

 

[Old Man with Gun]

I wouldn't pick 6 ARC for that distance. Limited to lighter lower BC 6mm bullets and low velocity. 6 Creedmoore will shoot much flatter, drift less in the wind and have more splash to figure out how to get on target. 6 ARC is hard to even hear if you hit steel.

 

[Bantam1]

I shoot my 6 ARC to 1K quite a bit. Using a 20" Proof carbon barrel. Zero issue hearing it hit steel and I have a flasher anyways. A hair under 10 mils of drop with the Hornady 108 ELD factory load for my AO. I think it shoots very well at distance. For a light rifle that is semi auto, it does exactly what I wanted it to do. It has done better in the wind that my friends large frame in 308 with a 22" barrel. He only shoots the 185 Berger which does pretty well at distance typically. Does it out perform my other rifles? No. It's easy to shoot, great for new people and has basically no recoil.

I have been using Duramag and ASC mags with no problems so far. I have been using the 15-20 round only.

 

[TonyTheTiger]

Having small frame AR's in 6mm, 6.5mm and some pretty spicy 5.56 loads, I wouldn't build any small frame specifically for 1000+ yards.
That's all marketing hype. Sure, it can get there, and all of the latest and greatest cartridges will do it better than 5.56 and get there transonic given ideal conditions, but none of them are optimized for it or as good as a short action cartridge will be.

 

[Old Man with Gun]

I shoot my 6 ARC to 1K quite a bit. Using a 20" Proof carbon barrel. Zero issue hearing it hit steel and I have a flasher anyways. A hair under 10 mils of drop with the Hornady 108 ELD factory load for my AO. I think it shoots very well at distance. For a light rifle that is semi auto, it does exactly what I wanted it to do. It has done better in the wind that my friends large frame in 308 with a 22" barrel. He only shoots the 185 Berger which does pretty well at distance typically. Does it out perform my other rifles? No. It's easy to shoot, great for new people and has basically no recoil.

I have been using Duramag and ASC mags with no problems so far. I have been using the 15-20 round only.

I have taken my 6.5G to 1k and can say the same, it is fun and doable under good conditions.

But my 6.5C SP-10 is much easier to shoot, deals with wind much better and the splash is much easier to see. I've hit steel at 1k with my 24" varmint 5.56, but I wouldn't call it a 1k rifle.

Maybe I am being unfair, if the OP wants to push a small frame AR to 1k, 6ARC is as good as any to get there. If the goal is to do well at 1k, large frame is way better.

 

[Dogtown]

I’ve made hits on 2/3 IPSC steel at 1000 yards at night with a 16” 6ARC shooting 103 ELD-X. It’s a more capable long-er range cartridge than 5.56mm, but wouldn’t be my first choice if 1000+ yards was the goal. I shoot a 6mm Creed AR10 for that, but there is a BIG difference between those two rifles. Now if I compare the 16” 6ARC with a 16” 5.56 - identical in nearly every aspect and that’s really the strength of 6ARC.

 

[Rob01]

I shoot factory 108 ELDs in my 22” 6mm ARC to 1000 without a problem. I bought a Grendel Hunter upper for about $800 and dropped it on one of my .223 lowers.

6mm ARC Uppers | Grendel Hunter | The Modern Sporting Rifle

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www.grendelhunter.com

Sure you can say a short action cartridge like a 6 Creed will do it better but where do you stop? A magnum will do it better than the 6 Creed. So? Guy wants an AR small frame to get to 1000 the ARC will do it.

 

[Ledzep]

First of all, semi auto and 1000yd is not two things that I typically associate. The flexible POI issues, gas system tuning, general finicky behavior in the world of semi-auto dispersion... You will experience success in spurts.

That being said, I'd look at a 20-26" barrel. The Geissele 20" rifle is a solid plug & play option although I wish it was 22 or 24". Otherwise build a rifle up with a quality heavy barrel in 24" with rifle +1" gas. I ran PRS gas gun last year with that setup (Bartlein barrel from CLE before they shut down). I hit a lot of the long ball targets at PRS matches, including the mile target at the Hornady PRC... BUT I also was very frustrated with the rifle coming from shooting a bolt gun. Again, documented POI shift with handguard load, aluminum receivers, a laundry list of factors that can axe your dispersion capability that don't really play a part with a bolt gun... So getting consistent first-shot hit at 1000+ with a semi auto--- When people say things like this to me I tell them to recalibrate their expectations.

But if you want something that is viable for IPSC targets 0-800 with the ability to rapidly re-engage until you hit out to 1500, sure. It'll work for that.

 

[Old Man with Gun]

First of all, semi auto and 1000yd is not two things that I typically associate. The flexible POI issues, gas system tuning, general finicky behavior in the world of semi-auto dispersion... You will experience success in spurts.

That being said, I'd look at a 20-26" barrel. The Geissele 20" rifle is a solid plug & play option although I wish it was 22 or 24". Otherwise build a rifle up with a quality heavy barrel in 24" with rifle +1" gas. I ran PRS gas gun last year with that setup (Bartlein barrel from CLE before they shut down). I hit a lot of the long ball targets at PRS matches, including the mile target at the Hornady PRC... BUT I also was very frustrated with the rifle coming from shooting a bolt gun. Again, documented POI shift with handguard load, aluminum receivers, a laundry list of factors that can axe your dispersion capability that don't really play a part with a bolt gun... So getting consistent first-shot hit at 1000+ with a semi auto--- When people say things like this to me I tell them to recalibrate their expectations.

But if you want something that is viable for IPSC targets 0-800 with the ability to rapidly re-engage until you hit out to 1500, sure. It'll work for that.

Perhaps I took the statement about AR too generally and thought large frame was on the table. If he wants small frame only, sure.

 

[Ledzep]

In my experience the dispersion factor isn't greatly different between the large and small frame systems. That's the primary limiting factor IMO. The 6 ARC with comparable barrel length and 105-110gr bullets can achieve trajectory that's pretty much equivalent to 6.5 Creedmoor 140gr. 6mm Creed will buy you some better trajectory.

Dispersion cone of fire is not linear, it degrades as you go down range. If it's a 1-1.5 MOA system at 100yd (extreme spread on 20-30 rounds), however, you can expect a 2-3 MOA system by 1000yd, plus your inability to read conditions, plus POI movement with variable fore-end loading, plus MV spreads, drag variability, etc. That cone of fire starts getting pretty big depending on target size. Granted, most rounds will go towards the center of that cone, you're still up to random odds as to where any one given shot will go. Again, depends on what you're going for. With 15-20 rounds in a semi auto you're going to hit, just a matter of how many rounds you sling at it before it happens.

 

[TrevK]

Built the wife a 18in 6arc. I decided to take it to the local range and qualify out to a 1,000y with it. Then handed it to my buddy(never shot anything past 300y) with my dope book and he immediately qualified out to 1,000 as well. Avg wind speed was around 18mph. The RO working there was shooting his 20in 6arc right along with us while we qualified. More than happy with this little cartridge.

 

[Old Man with Gun]

Built the wife a 18in 6arc. I decided to take it to the local range and qualify out to a 1,000y with it. Then handed it to my buddy(never shot anything past 300y) with my dope book and he immediately qualified out to 1,000 as well. Avg wind speed was around 18mph. The RO working there was shooting his 20in 6arc right along with us while we qualified. More than happy with this little cartridge.

How hard is the qualification? The targets I usually shoot at are just under 2moa at 1000.

 

[TrevK]

How hard is the qualification? The targets I usually shoot at are just under 2moa at 1000.

It was insanely easily, the range doesn’t take themselves too seriously, so there is no 2 tries per distance or some lame rule I’ve seen at others. They have torso plate, 24x20, and a big circle gong(maybe 18in?) at the 1k mark. Ring steel and prove you won’t be an asshat that shoots over the massive berm and you’re gtg. My buddy and I both got hits on the 24x20 within a few rounds. Wind was gusting hard enough that the torso seemed like a waste to try.

To be fair.. I’m building myself a 6.5creed AR10 to shoot alongside the ole lady at the same range.

 

[thedude824]

I’ve made hits on 2/3 IPSC steel at 1000 yards at night with a 16” 6ARC shooting 103 ELD-X. It’s a more capable long-er range cartridge than 5.56mm, but wouldn’t be my first choice if 1000+ yards was the goal. I shoot a 6mm Creed AR10 for that, but there is a BIG difference between those two rifles. Now if I compare the 16” 6ARC with a 16” 5.56 - identical in nearly every aspect and that’s really the strength of 6ARC.

The new story is I’ve got my old patrol 16” Colt that has been shot twice in 10 years. It sits in the safe. It’s very accurate, but it’s a carbine gas and a regular carbine buffer. My 14.5” does everything it will do in a smaller smoother package. I can’t part with it so I’d like to turn it into something I don’t have. Im now considering 6.5 Grendel since Criterion makes an 18” barrel with rifle gas so I can use a Superlative Arms piston setup. I like the idea of heavier bullets. Even if 800 yards is max that will be plenty to make it unique. I’ve got the A5 system on my 14.5” and the superlative arms piston kit and I absolutely love the combo. This is pretty much an upgrade for a receiver set that I really like and would like to have a reason to grab. I think I’m going to grab the NightForce 2.5-20 in the next couple days and the rest of the components. I much prefer ambi lowers, but for its intended purpose I’m not seeing a convincing reason why I should build this in an ambi set.

 

[thedude824]

I truly appreciate the tremendous ballistics discussion however. I’ve been doing searches and didn’t want to ask something that has been asked/discussed thousands of times. It has been tremendously enlightening. I’m loading some 169 grain SMKs for my MRAD in 308 to see if 1000k is attainable. I’m doing load development with 3 different bullets in 338 Lapua to shoot further. This build is for fun and to soothe my OCD about every system having a different purpose and being used. I haven’t gotten around to it yet, but I also plan on seeing how accurate my M82 can be by doing some load development with 750 Amax and single feeding. So this is definitely not a build that I’m “counting on” for 1k yards. I would hope that I could count on it for 800 yards and I definitely expect no less than .75 MOA @ 100 yards by the time load development is done. Admittedly I enjoying building/buying more than testing.

 

[Dogtown]

Did I read your posts wrong or were they just a stream of consciousness?

 

[Ronws]

This is another good reason I like SH. I learn something new nearly every day. I had not seen this side of 6 ARC.

I know from Social Regressive that it is a good truck gun and he kitted up a 6 ARC from CMMG. The idea was to hit varmints and predators and even take deer at 200 yards - ish (east Central Oklahoma, that is about a max good shot, anyway.)

I know from Texas Predator Hunting that Wade has fancied using his 6 ARC for coyotes. Sometimes hogs, but mostly 'yotes, using a call. Although, he will sometimes leave a dressed out hog for bait.

But I had not thought of it for 1k yard targets. Cool beans.

 

[MSTN]

I live at 5000', so shooting long range is easier for me than folks stuck closer to sea level. I have no problem at 1000 yards with the 6ARC out of an 18" barrel.

For people closer to the center of the earth, there's this 20" Proof SS on a Radian builder's kit that might work:

 

[thedude824]

Did I read your posts wrong or were they just a stream of consciousness?

Lol.. yep.. pretty much pointless droning. Sorry about that.
I basically chose to go 6.5 Grendel because I really wanted to use the Superlative Arms kit. 6 ARC isn’t available from the couple of barrel makers I trust in an 18” with rifle gas. Criterion offers the barrel and an headspaced JP bolt and I get an LE discount. Unfortunately Criterion is OOS with no ETA.
Proof offers a stainless 18” with rifle gas, but it’s literally 2x the cost and I see no option for a headspaced bolt. I may end up going with Proof if the Criterion isn’t available soon.
I see Craddock offers an 18” with rifle gas. Only a little more than Criterion. Opinions on that option?

I did notice several complaints about the rings JP uses in their bolt. Has that been rectified or should I go with a different bolt?

 

[ma smith]

@Lowlight did video below on modern 308.


Have you looked into the 8 twist MRAD barrels in 30 cal? maybe you can stabilize Berger's 200.20x hybrid in addition to 185s and 169s etc.

 

[thedude824]

@Lowlight did video below on modern 308.


Have you looked into the 8 twist MRAD barrels in 30 cal? maybe you can stabilize Berger's 200.20x hybrid in addition to 185s and 169s etc.

I haven’t. I use the 308 barrel as a “training” barrel and the 338 Lapua for long distance once I get better at longer distances. If I get another barrel it will probably be 300PRC. I just checked. My MRAD 308 barrel is 1:8.

 

[thedude824]

I read a couple threads and saw nothing but glowing reviews about the Craddock barrel. So I ordered everything this evening with the exception of the Superlative Arms piston system since it’s out of stock everywhere. This rifle (like all but the M82) will only be shot suppressed. I had planned to do the HUXWRX Flow 6k, but 6.5 Grendel is too big. I’ve already got a HUXWRX FLOW 762, but I leave that on the SCAR.. I’ve got a Hybrid 46 that stays with the MRAD… so I’ll need to figure out what I’m going to do with this one.. or if I’m going to start swapping cans.. maybe the HUXWRX Ventum?

 

[thedude824]

Figured I’d update with the finished product. I went with the 18” Craddock RTR 6.5 Grendel. I had to heat the upper quite a bit to get the barrel fitted.
Of note, I had issues with the Superlative Arms BCG having significant friction in the upper. I lubed the BCG and upper profusely and worked the BCG about 100 times. There were some feeding issues when I took it to function check and zero the scope, but that could also be related to the newness of all of the components. I used Durham 10 round mags. After about 30 rounds it fed the last 5 appropriately and without issue. I need to put a lot more through it to determine its reliability, but it seems promising at this point. There was some denting of the brass at the shoulder, but nothing excessive. I saw numerous posts about the superlative arms piston BCG exhibiting binding in some uppers. The accuracy was excellent as you would expect from the components used. The gas piston was fully open and ejected at three o cloth with the HUXWRX Flow 762.
I updated the OP with accurate parts list.

 

[thedude824]

I also purchased a couple boxes of Lehigh 110 grain solid match and a couple boxes of 110 grain controlled chaos.
For break in I bought 2 boxes of 120 grain Scenar L loaded in Starline brass.