r/6ARC

Looking to get a case trimmer pilot, however Lyman doesn’t have one for the cartridge. Will 6.5 grendal case trimmer work as a substitute?

I have been looking into 6 arc suppressors for awhile now and just can not decide on what to get. Currently running a 30 cal can and using a plan b muzzle device. Any ideas would be awesome!!!

I'm building a medium-tier precision AR in 6ARC around a BCM thermal fit upper that's been lapped and accurized by a machinist. Probably going with an 18 inch barrel, but might cut it back to 16 as I'm planning to put a can on it more or less permanently (probably OCL Polonium-K).

Who's used a carbon fiber barrel from some of Proof's marginally cheaper competitors like Carbon Six, Bartlein, Benchmark, or BSF? I was also taking a hard look at Boss Barrels which seems like it's a LOT cheaper and 95% as good. Any other recommendations?

Just recently finished building a 6.5CM on an Impact 737 action, Proof CF 22” barrel, NF NX6 and MPA Ultra Light chassis. Goal was to build a rifle to qualify for NRL Hunter Light (less than 12lbs) I do enjoy shooting it but I also have a 12.5” Noveske 6ARC that can do about 3/4” MOA with factory ammo.
My goal with the 6 ARC Bolt gun is quality action, quality barrel 16-18”, and a chassis. I honestly don’t want to drop the same amount of $$ into this as I have the 6.5CM. Not saying I wouldn’t but $1500 for a bare action hurts…. I would really like to hear some build component suggestions. My head hurts trying to filter through what and where to get started. I don’t want to go longer than 18” and I still prefer a “light” gun. Thank you 🤘🏻

I am putting a scope on my 6arc 14.5” and the 3-18x50 seems like a stand out choice for a budget scope comparable to razor 3-18. But at ~30oz and ~14” I think it may be too much?

I want to build it as an spr I can compete with and take shots to the maximum range of the rifle but still want to be maneuverable in terms of the advantages of 14.5”

If you have this Athlon on your 6arc please share your experience.

Thank you

Edit: I’ve done my best confirmation bias on the comments and pulling trig on the Athlon

I currently have a BSF stainless barrel I bought last fall. I’m considering buying a proof, MTE, or a Rexus steel barrel. I haven’t even finished building my 6 arc so I haven’t even shot a round through it. I really wanted a proof barrel but bought the BSF since I thought I’d be done with my build much sooner then that fizzled out. Would you keep the BSF and see how it shoots or sell it and buy a different barrel? I’m not sure how well everything will fit either with the BSF needing a .875 gas block and the handguard with clearance. That’s another reason I’m considering selling the barrel and going a different route. Thanks for any help and replies!

I was going to build a 16in 556 now I’m thinking 6arc but I already have a 15in rail that I was planning to use. What’s a pretty good sub moa barrel that’s 16in? Not quite proof barrel price range but like noveske or lower priced. I would go with noveske but I don’t really want a 14.5 or 18

I am looking at reloading 115 grain burger bullets into the 6 arc and was wondering if there was any data on that heavy of a bullet and am thinking of using Winchester staball match or staball 6.5 any recommendations requested

Looking for opinions on suppressor choice. 50/50 use between .308win and 6mm arc. The 308 is a tikka t3 used for hunting and mid range target. 6mm arc is on a howa mini bolt action for hunting only and also to be used on a 21” gas gun for long range target only.

Looking to keep weight under 10oz and not longer than 7”, ideally less for hunting. I prefer sound suppression over flow.

Kind of narrowed my search down to Enticer S ti, TBAC ultra 7 or 5, Mack Bros Zenith or Zenith -k (thank you Mr. Hamilton/Muckenhirn), or hux flow.

I already have a YHM R45 and some .22LR cans so not a complete stranger to the game.

Thoughts?

I am openly complaining about an industry wide design problem I believe we are seeing so that more companies will address their engineering limitations, and provide better products and feedback. YouTube video to follow. Hoping I get informative feedback. Also to inform others in how to diagnose their gassing issues in this now endemic malnourished weapon system.

TLDR: manufacturers are undergassing their barrels by porting too small and providing lower than acceptable dwell time for the cartridge.

I will start with the basics about me.

I’ve built many AR15s and 10s for myself and friends, have some precision gunsmithing friends I shoot with and shops I field questions to. I’ve spent almost two decades of competitive amateur shooting. Most of it is in multi gun, military, and tactical, with the past 6 focused almost entirely on precision rifle type matches.

My background in business is logistics which gives me a foggy window into production.

I personally have a sample size of 4 6ARC barrels and have now met in person at least 11 other shooters who have experienced the exact symptoms I am posting about, and a cursory search of this page is indicative of the same epidemic.

Obviously everyone’s sample of their own forms their opinions, and are often defensive of their investment, sunk costs and all.

The problem appears to be dramatic under-gassing of the rifles. Addressing the 8 cycles of function feeding-chambering-locking-firing-unlocking-extracting-ejecting-cocking The symptoms largely are feeding and extraction related.

1. extracting short stroke failure to lock back on an empty magazine. This occurs when the bolt does not return fully behind the magazine.

2. Feeding failure (most common) due to the round not being fully picked up. The timing of the pickup is important as the round must raise enough to contact the magazine feed lips to position the bullet for the feed ramps. If the bolt moves forward too soon it has less power due to not acquiring full spring compression, and may deflect the projectile into the gap of the chamber extension feed lips and the upper reciever or misdeed the round skyward into the chamber almost sideways. This is exacerbated with the large shoulder, narrow and long projectile profile and the wider cartridge needing more time to fully rise in the magazine. The damage results in dented shoulders and marred tips/broken ballistic tips.

3. Ejecting the pattern is most commonly in the historic under gassed range of 4-5 o clock ejection pattern. 4 is good if you’re building a race gun that dribbles out brass in pristine conditions such as 3 gun or a bench, but not hunting or combat. Notably an M4 or M16 eject m855 and m855A1 at about 2 o clock ( overgassed )

Diagnosing the problem:

Obviously if the claim is that the manufacturers are making unreliable barrels, how do I measure and identify it as the culprit: eliminate other weak areas by testing.

A. Ejection pattern is a known test to identify gassing pressure, but this can occur due to numerous issues as there’s more than just gas. Gas is the fuel, there’s inertia of mass, friction of parts and spring tension.

How can we eliminate these to determine if they’re the problem? Reduce spring tension, buffer weight, and friction with oil and polished surfaces.

-simply put did it all.

Minus 20% spring weight with nylon coating, removed weights from a standard weight buffer (3oz) and brought it to 1.9 then 1oz (no weights inside)

Same ejection pattern, mildly better reliability: from 1/3 feeding failing to a 1/10 failure rate.

Oiled the ever loving crap out of a DLC coated BGC after fully cleaning.

The pattern was consistently 4-5 o clock. The feeding issue kept occurring, while improved in the right extremely pristine conditions, I wouldn’t ever consider that good considering I can go hundreds of rounds with any 5.56 rifle I own and milspec tan follower mags without cleaning.

So we addressed weight, tension, and friction for ejecting, what about feeding?

B. What if it’s the magazines: Duramags: multiple 10, 15 and 20s tested. Asc as well. It is well established that duramag is of the better option by many users of this cartridge regardless of the issues they’ve had to address with their gun, a Dueamag is often the first way of addressing a feeding issue.

Maybe they’re not as good as some say? Have you tried the bent lips trick? Yes I bent the lips up on some 15s ever so slightly to see if a tip up positioning would improve it. I had less broken tips (3 from 45 rounds instead of ~3 from a single mag)

C. Address ammunition maybe your home brew ammo is junk.

I wish it were that simple. I’ve had this issue through 60 rounds of Hornady 108 match, 80 rounds of Hornady 105 black alone on two different barrels.

My cousin has some less issues than I and he also experienced it. I will say they ran better but still show undergassing signs and I had more than one double feeds on the Hornady blacks.

I have at least 550 rounds of starline hand loads with 90 grain Sierra TGK run in both barrels I tested. My cousin has about the same between his two builds.

Ok so what sample of barrels are we talking about:

Proof research 14.5 carbon mid length gas

Faxon 16” gunner mid “intermediate” length gas

Faxon 20” fluted rifle length gas

Ranier Arms 18” fluted rifle +1

We started with the faxons because we’ve had good luck I’d say and didn’t know we’d like the cartridge enough to do more than just a bolt and barre swap. They weren’t accurate enough for me. He built another gun and I fully converted and dedicated a match gun.

The ranier is the lowest performing in reliability. The Faxons are most reliable but least accurate.

Ok so how do we determine that it’s the barrels.

Well right off the bat: if a rifle is using good ammo, magazines, bolts and head spacing are good, no wear or damage it should cycle well and eject around 3 to just past o’clock typically using a standard carbine buffer and spring. We also tried JP silent captured springs from other builds.

In the end the only way to see real improvement was to reduce weight and friction, which means they’re undergassed.

So let’s compare the barrels.

The two areas of difference in the same chambering to consider is dwell time to total volume of available gas (the time the round spends inside the barrel past the gas port and the amount of gas it can harvest to direct to the BCG) and port size (the diameter of the gas port itself which allows the rate of flow. Rifle twist rates can add friction for dwell time but it’s a microscopic difference. All of these are 1:7 except the proof which is 1:7.5

Why are the faxons more reliable? Easy; longer dwell times and larger gas ports.

Proof research 14.5 carbon mid length gas

has ~5” of available dwell bore and gauged at 0.083”

Faxon 16” gunner mid “intermediate” length gas

Has ~6.5” of available dwell and guaged at 0.097”

Faxon 20” fluted rifle length gas

Has ~7” of available dwell and gauged at 0.096”

Ranier Arms 18” fluted rifle +1

Has ~4” of available dwell and gauged at 0.086”

Of note I attempted to use adjustable gas blocks to no avail, as over-gassing wasn’t even a thing suppressed and wide open still had issues. I was advised here and on the range to run a fixed low pro and it helped again. Stacking small gains but not solving the problem.

The weapons also cycle better with suppressors indicating it is still very gas related. The final straw was when I found out that some manufacturers like Odin had reportedly began increasing their port sizes to 0.106”! Let’s not forget that this is only 6 years on the market in a niche area of gas gun precision mid range shooting enthusiasts. Of course there are growing pains. At the adoption of the AR15 it took the military years to identify and replace the buffers to work reliably in combat on the m16 and m16A1 models.

So I ported my ranier the most undergassed of the bunch to 0.103” and what do ya know? Best performance ever. Granted I’m still running a 1oz buffer but a standard spring. It cycled well with 3oz but the EP was at ~5 so I went back to 1oz for a 3:30 pattern. 125 rounds so far and no issue.

So why do I think this is happening in so many barrel makers? 1. Frankly the number of posts here. Never meeting another 6 arc shooter who didn’t have the same issues, and the makers are selling the long gas systems with low dwellings times.

Why are they doing this? Likely tooling. From the small precision shops I talk with customization is their market. They hand lathe their barrels. But major brands are mass producing thousands a year and so they are tooled and dedicated to do runs of barrels. It’s far easier to revive blanks with ports lengths pre located. Particularly when conducting fluting or carbon wrapping. While I can be wrong on this hypothesis, after all that’s its point is to be tested and checked, I believe the tooling is a main culprit. They’ve dedicated themselves to precision and a market who tells them what they’d like. It’s cool to get the 18” 5.56 fluted barrel with the rifle +1 ‘carbine? Ew, it will be too gassy’ well now you make a 6arc and the comments I see here proclaim the same? Why would you want a mid length on an 18”? “Swing and a miss” -direct quote about a WC barrel design

So in conclusion, we need to be informing these manufacturers to open up ports and provide several inches of available dwell. Particularly when the gasses in this efficient cartridge are burnt so much more and cooler than 5.56 by the rifle length (or more) position tube. Since the bore is wider back pressure drops quickly, while the bullet, particularly light ones, is traveling faster than say a 6.5 grendel.

It should not be acceptable that companies like proof research add notes stating “not guarantee cycling for projectiles under 100 grains” - an admission of failure to design right. When you would never accept someone saying the same for 55grn in 5.56.

Just food for thought. If you made it this far you’re equally to or more autistic than I and I await your wall of complimentary or angry text. Thanks forum. You’ve been helpful on these insights. I will be emailing and calling the manufacturers to provide this feedback.

Thinking of building a 6 arc to reach out and touch some stuff. I had mentioned it to my buddy and he asked me “you man enough to put your FRT in it?” As a /s, but it got me to thinking…. I wonder what that would be like. Not that it would be practical or cheap.