A 6MM ARC upper on the economic side

[Tinker-S]

It has been a while since I gathered AR parts to put together an upper, and I wanted to put together an AR15 upper chambered in 6MM ARC. I took apart one AR15 upper that was collecting dust, and used the upper receiver for this project.
This is what I purchased:
Ballistics Advantage 18" 1:7 RH twist DMR barrel: $175.00
Rifle length gas tube: $10.00
Stoner complete BCG (the shiny kind): $100.00
Superlative adjustable clamp-on gas block: $85.00
DoubleStar tubular 12" hand guard and barrel nut: $75.00
Muzzle brake with jam-nut from Grendel Hunter: $24.00
Two magazines: $24.00
All in all, I spent $493.00 plus shipping/taxes.
I acknowledge I could have purchased a complete CMMG upper from Midway for $499.00, but then I would have started to change things, like the gas block, and if the gas block would not fit under the hand guards, I would have had no choice but to replace it with something else. If the new hand guard would have used a different barrel nut, I would have ended up taking the whole thing apart, and I do not like that. So, I purchased what I like/want, and put it all together.
The upper, paired with a lower, function as expected, and the recoil is almost like of a .22LR. I was testing a powder/bullet combo, and I experienced what some people calls "pop and no kick". I thought there was bullet stuck in the barrel, and I proceeded to remove the BCG, and I was pleasantly surprised! There was no bullet stuck, and so, I continued to fire the rest of the rounds without much issue. Well, almost without issues: One of the magazines acted funny. The rifle would chamber a round but if failed to fire. I thought that my reloading skills were gone with the wind, so, I separated the "bad" rounds, and started to pack up to go back home and take the ammunition apart, but I decided to use a different magazine, and the rifle fired without any issues. Weird!
This rifle does not beat the brass as my 6.5 Grendel does, and I am hitting targets as far as 645 yards so far, but I have not settled on a powder/bullet combo. I think the rifle likes the 105 Barnes Match Burners and BLC, but does not like the 105 Hornady BTHP Match either with BLC or CFE 223. I will try Varget and 107 grain bullets when available/delivered. On one of the best groups so far (Sub-MOA), I used some 6.5 Grendel PPU brass with large rifle primer, 105 Barnes, and BLC.
So, I am happy with my complete upper on a budget.

 

[troy fairweather]

Need pictures, I haven't seen any 6arc cmmg uppers or barrels shoot very well.

 

[12Bravo20]

I did something similar but used an Odin Works 18" barrel with +2 rifle gas.

I have only tried factory ammo in mine and so far the Hornady 108Gr ammo does the best. This upper is also one of my test rifles for different inexpensive scopes. The rifle has done great even with the Arken SH4 scope compared to my better/higher quality scopes.

And yes the higher end scopes are definitely better as far as glass quality/clarity goes.

 

[Tinker-S]

I did something similar but used an Odin Works 18" barrel with +2 rifle gas.

I have only tried factory ammo in mine and so far the Hornady 108Gr ammo does the best. This upper is also one of my test rifles for different inexpensive scopes. The rifle has done great even with the Arken SH4 scope compared to my better/higher quality scopes.

And yes the higher end scopes are definitely better as far as glass quality/clarity goes.

No factory ammo or brass is available. I am reloading converted 6.5 Grendel brass. Most of my range buddies have/are awaiting on their upper from vendors like Shaw. Most people I know is waiting on reloading components, and some have purchased factory ammo at premium price.
For scope, I am using an el cheapo Mil 10x fixed Bushell with a 20MOA Extended scope rail to get me to 1K yards. I will probably upgrade it in the future, but for now, that's what I will use.

 

[NR53]

I am thinking of building an upper also. Also with an 18" barrel with rifle length gas system.
I was in my local gun store last week and my longtime friend behind the counter tried to sell me a bolt gun chamber in 6MM ARC. I told him I didn't want one until Starline started making brass for it. He said" They are, but it's got a Hornady headstamp on it." Don't know for sure it that's true, but I am within 50 miles of Sedalia, MO and Starline, so I'm pretty sure there may be local people that work there. If it's true, then Starline should eventually offer 6MM ARC brass for sale.

 

[horsemen61]

It has been a while since I gathered AR parts to put together an upper, and I wanted to put together an AR15 upper chambered in 6MM ARC. I took apart one AR15 upper that was collecting dust, and used the upper receiver for this project.
This is what I purchased:
Ballistics Advantage 18" 1:7 RH twist DMR barrel: $175.00
Rifle length gas tube: $10.00
Stoner complete BCG (the shiny kind): $100.00
Superlative adjustable clamp-on gas block: $85.00
DoubleStar tubular 12" hand guard and barrel nut: $75.00
Muzzle brake with jam-nut from Grendel Hunter: $24.00
Two magazines: $24.00
All in all, I spent $493.00 plus shipping/taxes.
I acknowledge I could have purchased a complete CMMG upper from Midway for $499.00, but then I would have started to change things, like the gas block, and if the gas block would not fit under the hand guards, I would have had no choice but to replace it with something else. If the new hand guard would have used a different barrel nut, I would have ended up taking the whole thing apart, and I do not like that. So, I purchased what I like/want, and put it all together.
The upper, paired with a lower, function as expected, and the recoil is almost like of a .22LR. I was testing a powder/bullet combo, and I experienced what some people calls "pop and no kick". I thought there was bullet stuck in the barrel, and I proceeded to remove the BCG, and I was pleasantly surprised! There was no bullet stuck, and so, I continued to fire the rest of the rounds without much issue. Well, almost without issues: One of the magazines acted funny. The rifle would chamber a round but if failed to fire. I thought that my reloading skills were gone with the wind, so, I separated the "bad" rounds, and started to pack up to go back home and take the ammunition apart, but I decided to use a different magazine, and the rifle fired without any issues. Weird!
This rifle does not beat the brass as my 6.5 Grendel does, and I am hitting targets as far as 645 yards so far, but I have not settled on a powder/bullet combo. I think the rifle likes the 105 Barnes Match Burners and BLC, but does not like the 105 Hornady BTHP Match either with BLC or CFE 223. I will try Varget and 107 grain bullets when available/delivered. On one of the best groups so far (Sub-MOA), I used some 6.5 Grendel PPU brass with large rifle primer, 105 Barnes, and BLC.
So, I am happy with my complete upper on a budget.

Leverevoultion is the powder you seek! It’s awesome in mine everyone I’ve talked to said the same thing it and a 105 match bullet is an awesome combo

 

[Tinker-S]

Need pictures, I haven't seen any 6arc cmmg uppers or barrels shoot very well.

I need to see how to upload pictures. And yes, I have heard that from CMMG economy line, but I have never used one of their uppers. I know their premium line comes with most upgrades that the average user would want in their uppers.

I am thinking of building an upper also. Also with an 18" barrel with rifle length gas system.
I was in my local gun store last week and my longtime friend behind the counter tried to sell me a bolt gun chamber in 6MM ARC. I told him I didn't want one until Starline started making brass for it. He said" They are, but it's got a Hornady headstamp on it." Don't know for sure it that's true, but I am within 50 miles of Sedalia, MO and Starline, so I'm pretty sure there may be local people that work there. If it's true, then Starline should eventually offer 6MM ARC brass for sale.

I am sure there will be brass available in the future, whenever that is. Even the reloading dies are scarce. I like the small base dies from RCBS, and their price just went up. Because of availability, I purchased Lee dies. They are good, in fact, most of my reloading dies are Lee, and I have no issues with them.
Shop around for components for your upper, and get what you want. The cartridge is versatile and great to shoot.

 

[Tinker-S]

Leverevoultion is the powder you seek! It’s awesome in mine everyone I’ve talked to said the same thing it and a 105 match bullet is an awesome combo

I have heard some people at my club say the same, but I have not seen them to shoot their rifles, so I do not know how it performs. My local store has Leverevolution in stock, but at least on paper, BLC is just about the same in performance. Yes, BLC is dirty, but I do not mind since it seem to do well in my rifle, and I have at least 2 lbs. of the stuff on hand. I am set to wait for Varget to be available in an 8 lbs. container, since it will be used in 90% of my applications.
What brand of bullets do you use?
I do appreciate your input.

 

[horsemen61]

I have heard some people at my club say the same, but I have not seen them to shoot their rifles, so I do not know how it performs. My local store has Leverevolution in stock, but at least on paper, BLC is just about the same in performance. Yes, BLC is dirty, but I do not mind since it seem to do well in my rifle, and I have at least 2 lbs. of the stuff on hand. I am set to wait for Varget to be available in an 8 lbs. container, since it will be used in 90% of my applications.
What brand of bullets do you use?
I do appreciate your input.

As far as bullets I use several different brands my best groups have come from Berger though

 

[Varminterror]

Leverevoultion is the powder you seek!

Just be mindful as the weather warms this spring. Powders rarely get more temperature sensitive than Leverevolution - it’s a powder I would highly recommend using the temperature correction features of your ballistic app, or at least catalog velocity change over daily temps and correct MV in the calculator.

 

[Tinker-S]

Just be mindful as the weather warms this spring. Powders rarely get more temperature sensitive than Leverevolution - it’s a powder I would highly recommend using the temperature correction features of your ballistic app, or at least catalog velocity change over daily temps and correct MV in the calculator.

Thank you for your recommendation. I will keep it in mind. I will follow recommendations and will go to the local store to pick up a one pounder of the stuff.
I generally stay at least 1.5 grains below what most reloading manuals recommend before max, with changes in temperature in mind, just so as not to change much, and I plan to chrono my loads as temp changes are happening. I try to keep an e-trail of time, place and loads used. Elevation does not change much, just ~200 sea level.
I do not reload in quantity, and sometimes I just reload enough for one range visit, between 20-30 rounds.

 

[Varminterror]

A grain and a half below max in 6 ARC would be well into Varget realm, which all but eliminates the temp sensitivity issue altogether. But you’re losing valuable speed from an already undersized cartridge, so I’d rather just be mindful with LR than give up 150fps. Loading with temp sensitive powders is kind of like highway driving without cruise control - it’s not hard, it just takes more attention than it otherwise could.

Something of note also - elevation, physical elevation that is - doesn’t tend to matter much for internal ballistics, it’s really just temperature. Physical elevation, relative humidity, and barometric pressure matter for trajectory, and even when you’re not changing physical location, it’s not uncommon to see a couple thousand feet of “density altitude” change for any given shooting range over the course of a year. Density Altitude is the effective air density - meaning the atmospheric conditions make the bullet feel like it is flying through air at the Density Altitude, not at the physical altitude. As an example, all 3 of my “home ranges” where I shoot regularly are 1200-1300ft, but I’ve seen Density Altitudes from -800 to +4500ft I’ve even shot ranges where we had 1500ft of change during a single day. It’s not a huge change, but the difference between 8am and 1pm a couple weeks ago was 0.3 mils at 1000yrds, over 10” difference in impact, even using a temp stable powder (rose from 20’s to almost 60, which would have been another ~6” or so, another 0.2 mils-ish if I were using LR). Adding atmospheric change and temp sensitivity, I’d have had a half mil of unresolved error, 18” at 1000, just because the hour hand on my watch turned 150 degrees.

 

[N555]

If you run 6arc it means you have money to burn.

 

[Demi-human]

If you run 6arc it means you have money to burn.

Why? Brass is brass, bullets are bullets, and powder is powder. Why would it be Thurston Howel to shoot a 6ARC as opposed to a Valk?

 

[Varminterror]

If you run 6arc it means you have money to burn.

If we’re playing silly, absurdist games, then if you shoot recreationally, it means you have money to burn.

But still, an interesting quip coming out of the dude which takes pride in over complicating the AR recoil mechanism.

 

[CapnMac]

I need to see how to upload pictures.

Note--the below is predicated on being on a laptop or desktop--mobile devices differ a bit.

If you have the photos someplace online--Imagr, Flickr, Google Photos, etc., you can right-click them, and you want to select "Copy Image Link."
Then, you can click on the Image button (next to the smiley face) in the Reply Toolbar.
That will pop up the Image Insert box. The cursor will default to the "Image URL:" box. You can use CTRL-V or right-click and select Paste, to insert the link. You will get something like this:

Note that the Image will "drop" to where ever the cursor is in the Reply box.

If your images are on your computer, you can use the "Upload a File" button at the bottom right of the Reply window. That will bring up the File Upload dialog box, which will have navigation tools to let you browse for where your photos are (that location will be "remembered" handily).
After selecting a file, you will see it appended to the bottom of the posting. Note that it has two buttons, "Thumbnail" and "Full Image."
You can insert either in the Reply text by moving the cursor to the desired location, then clicking the desired button.
Which looks like this

(Full Image) Or like this:

(thumbnail).
Hope that helps.
6arc is such a fascinating round, it's a shame that it's being ignored by the ammo makers and rifle builders alike.

 

[Tinker-S]

A grain and a half below max in 6 ARC would be well into Varget realm, which all but eliminates the temp sensitivity issue altogether. But you’re losing valuable speed from an already undersized cartridge, so I’d rather just be mindful with LR than give up 150fps. Loading with temp sensitive powders is kind of like highway driving without cruise control - it’s not hard, it just takes more attention than it otherwise could.

Something of note also - elevation, physical elevation that is - doesn’t tend to matter much for internal ballistics, it’s really just temperature. Physical elevation, relative humidity, and barometric pressure matter for trajectory, and even when you’re not changing physical location, it’s not uncommon to see a couple thousand feet of “density altitude” change for any given shooting range over the course of a year. Density Altitude is the effective air density - meaning the atmospheric conditions make the bullet feel like it is flying through air at the Density Altitude, not at the physical altitude. As an example, all 3 of my “home ranges” where I shoot regularly are 1200-1300ft, but I’ve seen Density Altitudes from -800 to +4500ft I’ve even shot ranges where we had 1500ft of change during a single day. It’s not a huge change, but the difference between 8am and 1pm a couple weeks ago was 0.3 mils at 1000yrds, over 10” difference in impact, even using a temp stable powder (rose from 20’s to almost 60, which would have been another ~6” or so, another 0.2 mils-ish if I were using LR). Adding atmospheric change and temp sensitivity, I’d have had a half mil of unresolved error, 18” at 1000, just because the hour hand on my watch turned 150 degrees.

And that's why I got here in the first place! I always learn from hands-on experience.
I do appreciate your advice, and, yes, I went to the store after lunch. I was lucky and found two containers of LR on the shelf. Sweet! I didn't have to pay HazMat + S&H! and as a bonus, I picked up several bags of plastic Bass lures and hooks!
I prepped 20 shells and will add primers and powder tomorrow. Will have range time on Thursday, so I will not have anything to report till then.
I will use Hornady load chart, and see how it goes.

 

[Tinker-S]

If you run 6arc it means you have money to burn.

Well, I also run a big Diesel truck. I guess I do have money to burn. Wait! If I didn't drive, how would I get to work, and to the range, and to the lake?
Never mind. I always attempt to make sense of it all.

 

[Tinker-S]

Some pics of the 6MM ARC project.
I have to put together another lower. This one is for my SR upper.

 

[N555]

I got a diesel truck too. It stays parked most of the time. Haven't put fuel in it since 2018. It comes out about once or twice a year.

 

[N555]

If we’re playing silly, absurdist games, then if you shoot recreationally, it means you have money to burn.

But still, an interesting quip coming out of the dude which takes pride in over complicating the AR recoil mechanism.

That's a really weak straw man. I though you could do better than that.

 

[12Bravo20]

WOW! Here we go again. Hopefully this thread does not get locked

The cost of factory 6mm ARC ammo is around the same as other match grade calibers. Though 6 ARC has been harder to find in stock. I have been paying between $28 and $30 per box of Hornady 108Gr 6 ARC ammo.

As of right now no one makes new unfired 6 ARC brass so one would have to either save their Hornady brass or buy Starline 6.5 G brass and reform it. Again the cost of unfired new bras is the same as other calibers.

Reloading supplies are going to cost the same no matter what caliber you shoot. The main difference in cost will be powder since bigger calibers will use more of it.

Even with the limited availability of factory ammo and reloading supplies, 6 ARC is no more expensive than other comparable calibers. And I can still reload more 6 ARC rounds compared to .243 or 6 Creedmoor since 6 ARC uses less powder. Bullets and primers are the same no matter which caliber you are reloading. Powder is also the same price but you can get more rounds loaded with 6 ARC.

 

[gunmechanic]

You will enjoy the 6ARC it is a great cartridge .The components you chose are great it should perform well, let us know how it runs. I built a 6 arc I used the odin works barrel 21" 2+ gas system, rifle buffer system .I had an under gas problem ,even with the gas block wide open it would not pick up the next round.I talked to odin works they told me the early barrels gas ports were under sized for certain configurations. I had to open gas port to #35-.108 number drill then the gun ran reliably.Hope this help some one.

 

[Tinker-S]

I got a diesel truck too. It stays parked most of the time. Haven't put fuel in it since 2018. It comes out about once or twice a year.

Mine is a daily driver, but just for short rides. Once a month I have to take it for at least 50 miles, or else, they tend to go bad.

 

[Tinker-S]

You will enjoy the 6ARC it is a great cartridge .The components you chose are great it should perform well, let us know how it runs. I built a 6 arc I used the odin works barrel 21" 2+ gas system, rifle buffer system .I had an under gas problem ,even with the gas block wide open it would not pick up the next round.I talked to odin works they told me the early barrels gas ports were under sized for certain configurations. I had to open gas port to #35-.108 number drill then the gun ran reliably.Hope this help some one.

Nice to know.
My setup runs great! Well, so far that is. Only 40 rounds through it, but the gas systems is doing good. I had started with the wrong gas block setting, but on the second outing, it did fine.
I will load some rounds to test with LR, and will report as I test.