I would like to build a "tier 1"AR in 6 ARC.  I think 18" is what I am looking at but not positive on this yet, I need to look at ballistics charts and then judge the need for extra barrel length Vs lighter and easier to maneuver.  This would mainly be used at a 300 yrd plus ranges but the occasional close up shot is not out of the question.  I would like it to be able to reach out to 1200 yards but not willing to be swinging a 26" barrel in the woods.  AS A NOTE BEFORE I GET ROASTED....I would not be hunting probably beyond 400 yards...well maybe a prairie dog shoot I might test my skills but not on bigger animals.  This rifle will have multiple purposes.  I plan to add a can at some point.  I would also like to minimize weight if possible.  

I would like to know what parts I probably need to start looking at, I also have never really assembled an upper.  Not scared of it but usually better deals for a built unit, I have put together several lowers though.  

I will list the following, stuff I have, stuff I am seriously looking at, and stuff I have no clue....the first two list are really short.......I am open to buying stuff that I already have if the part suggested is significantly better than what I have...in other words this list is totally open to suggestion.

Stuff I have:
trigger:  I have both LaRue MBT-2S  or pretty sure it is a Geissele 2 Stage* (*not sure on the model type though)
Lower: either APC lower or I love sweeping up aluminum chips


Stuff I am highly leaning to get:
Barrel: AR proof research carbon fiber


Stuff I might do:
Folding stock: LAW tactical (have)


All the other parts I am open to:

Grip (this is highly personal but I don't have a particle grip I am attached to, open to suggestions I might have not heard of):
Upper (I favor a forward assist just because it was part of a drill when a misfire happened, old habits die hard):
Lower Parts kit (detent pins, springs, grip screw etc): usually CMMG kit has been my go to
Charging handle:
Bolt Carrier Group (believe this is the same as a 6.5 Grendel BCG, price is not a factor):
Gas Tube:
Gas block, probably want adjustable due to adding a can later but never had one before, not sure how critical):
Buffer and buffer spring:
Upper parts kit (not sure if this is sold as a package or order individually is best, things such as the forward assist, and ejection port cover and springs):
Castle nut (have the option for a quick release sling mount)
Barrel nut:
Hand guards will be Mlok with picatinny on the top (no real debate here as I have more of this than dickmod, will depend on barrel length before I narrow this down totally)
buttstock:  no clue on this yet

I am sure I forgot a few things, might modify these list as the thread matures so it is up to date on my thoughts.


I normally use LaRue quick release scope mounts, they have gotten pricey.  Anything of equivalent or better quality and maybe lighter.  I plan on putting an RMR at 45 on one set of rings.

I don't need help with the optic, though not sure if I want to run backup sights or not.

Just curious as to who's "tier" totem you are basing this build on

This isn't what you want to hear, but based on everything you wrote, I recommend buying something off the shelf and not building. You've got so many things going on here that will have downstream effects, that diagnosing malfunctions (highly likely) will be all but impossible. Between the inherent finickiness of 6mm ARC, +1 gas on the Proof barrel, the addition of a LAW folder, as of yet undefined buffer tube length/buffer weight/spring, the possibility of using an 80% lower, etc, not to mention the fact that you've never assembled an upper before....  you are not setting yourself up for success.

San Tan makes an excellent complete rifle, the STT-15 6ARC - it comes with an 18" Proof CF barrel. You can get it for around $2100 right now (LockedLoaded and Defense Depot, both on sale when added to cart). Considering you're looking at around $1600 in parts, I encourage you to spend the extra money and get a purpose built, tested rifle with a lifetime warranty. It is a top tier rifle with top tier parts, a gorgeous ambi lower with every feature, etc.

Save your first upper build for a 5.56 to do a little learning.

I just checked my Hornady load data for 6 ARC for an 18” gas gun.  LeveRevolution max charge is 2550 FPS with a G7 BC .253.   At 1000 yards your velocity is
1131 FPS with 298ft pounds of energy at sea level.   Unless you are at higher elevation there are better long range cartridges than 6 ARC.   The 6 ARC is a fine intermediate cartridge that can do several things well.   Unless you reload your ammo choices are limited with 6 ARC.   Honestly if your intent on shooting long range 600+ yards regularly I think you would be wise to consider the small frame AR-10 in 6.5 Creedmoor or 6 Creedmoor.   There is a great deal more factory ammo available for the 6.5 Creedmoor and it is a significant step up in performance.


I really like the AR-15 but the Ruger or POF small frame AR-10 perform better at long distances.   If you only occasionally shoot beyond 600-700 yards the 6 ARC might be worth buying.    To me the intermediate cartridges are better in closer where you are going to be carrying the rifle where size and weight is a concern.   Determine your goals then select the most appropriate tool.


https://ruger.com/products/sfar/models.html

With an Aero adjustable GB, I've really been enjoying my RCA Ti BCG and Unrivaled Competition Buffer.

I appreciate the response and will try to answer some of the questions in the replies.

I guess when I say "tier 1" I am referring to good quality parts.  Some people refer to this more as brand such as a KAC parts and many times the "brand name" and price does reflect the quality as well but not always the case.  To specify this some and define it.  To me good quality parts: the ability to be accurate, has longevity and I won't have to replace it 87x before I would another company, and also not have to tweak it 87 times to put it back in specs Vs an equivalent part that stays solid.  I understand in some cases there is a trade off in the "type" part purchased such as a chrome lined barrel or not.  I do not consider these equivalents for this thread.  That would be more of a choice of what I want in the end result.

I specifically picked 6 ARC due to being slightly better than most other "small frame" AR platforms at longer ranges.  Anything beyond the 700 yrd range would be more plinking than anything else...besides maybe the attempt on a prairie dog just to see if I could do it.  I already have several large frame AR's to include 6.5 Cr.  I already have a V-Seven 16" enlightened rifle in 6 ARC which is why I picked an 18" barrel for this one.  Most of this is just for me.  My physical limitations cause most of my grief with larger frame AR's.  

I was not aware the 6 ARC was more "finicky" than most other small framed AR's based on some of the replies.  I would agree it would be better to build a plain jane .223/5.56 to "see if it works" first if it is that much more of a pain to get a 6 ARC build right.  The LAW folder is just an option but not required, I can always make it work first and add this part and play with it later.

I took the 1200 yard range from this article: https://shootingsavvy.com/6mm-arc-effective-range/

"The Hornady 6mm ARC has a max effective range of 500-yards for deer hunting, 900 yards for coyote hunting, 1,000 yards for military use, and 1,300-yards for target shooting. Past 500-yards, hunting bullets will no longer expand enough for deer-sized game. At 1,000-yards the bullet lacks deep penetration. Past 1,200-yards, the bullet goes subsonic and loses stability."

Now that being said, not everything on the internet is true.  I do have the dies to reload my own, currently just shooting factory ammo and building up cases to use later.  Not a lot of brass on the market when I looked... but it has been a while since I looked much less bought anything.  At the time the only brass you could get was Hornaday and I might as well shoot a factory load and reuse it.

Why not go with a 12” or step up to a 20-22”?

There won’t be any measurable difference in performance between a 16 and an 18”.

Sounds like you’ve researched the 6 ARC and are working from a knowledgeable position.   I have several 6.5 Grendel AR-15’s and a Cz 527 American in 6.5 Grendel.   I have seriously considered adding a 6 ARC but age and family obligations have taken a lot of my available time to shoot.    I like the intermediate cartridges because they use less powder and cover most of my shooting needs /desires.    It is difficult to know how much experience a forum member has when starting this type of thread.    


At this point I’m leaning more towards the 22 ARC mainly because it appears to be a good varmint and target cartridge.   Already having a supply of bullets and components is a bonus.    Speaking of components Rexus/6.5 Outfitters has Starline 6 ARC brass in stock for $68 per hundred.   Good luck Op!


https://rexusoutfitters.com/starline-brass-cartridge-cases-6mm-arc/

Not really wanting to go the SBR route at this time, then not really wanting to swing 20" in the woods.  The one option might be to get a 14" barrel and pin and weld a can adaptor (that makes it 16") to the end, not sure how common this might be especially on a carbon barrel.  My 6.5 Cr has a 22" barrel the the .3 Oh Hate has a 20" barrel and part of the reason I pick something else depending on what I am doing.  For shooting stationary I like the bigger platform, for anything when I am moving around and might find myself in a tight spot....not so much.  

This will serve as a backup for the V-Seven in a pinch.  This should give similar results reloading the same ammo.

Well if you burn out one of the barrels and replace it, correct me if I am wrong but you could just get a 6 ARC barrel and run it.

Thanks for the brass link.  I have not even researched the 22 ARC round....

Since you have a can, any recommendations for 6 ARC?  Most cans I have seen people use are really for 6.5, of which would make it a dual use can.  I was looking at the surefire TI model for the weight reduction part, not sure if still made.  My other cans are YHM, which are not all that light.

I prefer quick attach models but getting this picky probably won't help me and willing to sacrifice in some areas.

What would ever give you the impression OP might be stubborn..... .

Still probably build a 5.56 first though.  Not like its a bad thing to have the skill to do it.

For my 6 Arcs I have a 12.5 Beer City Bullets (?), a 14.5 Noveske, a 16” V-Seven, and an 18” Proof. Haven’t shot the V-Seven yet but I have no doubt it shoots. The Noveske is solid. Of course the Proof shoots. What impressed me was that Beer City Bullets. I mostly got it because I liked the specs and it’s hard to find a 12.5 that’s not like BA or something. Turns out it’s one of the best shooting barrels I have, and I have some good ones. Would recommend.

I will say that while assembling an upper isn’t hard, this may not be a good one to start on. 6 Arc does have a bit of a learning curve, and there are a lot of things to make sure they all line up. Plus assembling an AR for accuracy is a whole different ballgame compared to just plugging in parts.

I’ve run three different cans on it: Rex MG7K.30, OCL Polonium K, and DDC Enticer S. Enticer is the quietest but longest, Polo probably the loudest but shortest, Rex in the middle.

Buy a Seekins DMR complete rifle and be done with it. You should be able to get the rifle for $1600 if you shop around and they’re absolutely amazing rifles. If/when the bolt breaks they will do whatever is required to repair it at zero cost to you, not even shipping if the upper has to go back. They build top tier stuff almost exclusively in house and stand behind it 100%. The value you get in their DMR rifle is great too.

PSA is making 6ARC ammo soon.  That will be a big boost.

Review of the RCA Ti BCG and Unrivaled Deadblow competition buffer I’m running in my 6 ARC. In conjunction with an Aero AGB, it is a very smooth shooting rifle.

Thanks,

I just looked at the DDC Enticer, I have to assume the variations are; S or L for Long or Short and Ti is for titanium Vs Stainless steel?  

Interesting the Polo seems to be much louder since it is meant for smaller diameter bullets, understand it is shorter though (maybe I took too much from that post though).

Correct about DDC and the length/materials. They use the Dead Air end cap thread pitch, and I have a 6mm end cap that I’m using on it, so that helps with noise. The Polo K is 6mm bore as well, but is louder since it’s got a smaller volume. Not a huge difference in sound between the 3, but just enough to be noticeable I think.

Here’s the DDC:

 This

Seekins factory gun would be my suggestion.

I built a 24" barreled 6arc for prs, BA barrel, aero adj gas block, sharps ambi lower, tt special trigger, seekins bar upper with sargent of arms 17" arca handguard, aero bcg, little bastard muzzle brake,
Seekins precision stock with standard rifle buffer setup. Atlas cal bipods rrs pic/arca mount

Has a reptillia 1.7 mount and for now a viper pst2 5-25.

Rifle is the damn easy button I'm getting almost 2700fps with 105 ncc and rl15.  9.6mils to 1000yd.

The 41st round from rifle was a neck hit on a 50% ipsc at 1000yds.

18” Proof SS barrel
Geissele rail, gas block, and trigger
CMC bcg

It has been through a few parts iterations. Very happy with the current setup.

That is a VERY NICE looking setup indeed!  Which Geissele Rail is that?




Any reason you didn't go with an adjustable Gas Block?

I’m addicted to those Mk18 rails, I think I’m up to 5 and wouldn’t mind a black one. I’m up to 4 DDC and one ODG at the moment

I originally started with an adjustable gas block and just could not get it to cycle correctly no matter what setting.
I went full Monty on the gas block then tuned it at the other end with a Viltor A5H2. Now it’s very smooth and cycles perfectly. Easy consistent hits out to +1200 with 108’s when breaking it in at Coleman’s Creek.

Originally used a 3.6-18 Mk5 but was hitting much farther than expected. 5-25 is great with the 18” Proof.

Nice rifle, I assume those are 16" and 15" rails?

Check out Argos Ordinance. Chad from IV8888 makes 6 Arc rifles and sells complete ones on his site. Chad loves 6 Arc and has a lot of time building them.

Sorry for the late reply.

Yes, 15” Mk16 and 16” Mk18 Geissele rails.