New 6mm Advanced Rifle Cartridge

I wish mine looked that nice.
1The bore is not shiny and the groves look like tank tracks down the barrel

(I do realize that this is zoomed many times so like if you look at your thumb, you’ll see dividing lines in your skin…)

The gas port now looks like someone spit black goo and it travel from the edge of the gas port and slowly formed a tingle pattern of black goo (not sure how to even describe it

I will post photos.

This is a barrel that I had initially called the manufacturer and he had said shoot it and if it doesn’t work out, he would make it right. He had thought that I was having some recoil issues going on so I put another hundred down the tube and it’s shooting horrible ..worse

I shot off essentially a adjustable height, rest, and a bag in the back
 
  • Like
Reactions: Jdowns0415
Yeah, I will be sending it in..
seems Iike it ends up with copper depositing right past the gas port. The gas port I guess is just Gasport erosion? It just looks way nastier than what I’m thinking, but the rest of it looks like a lot of chatter down the runway that has not smoothed out.

As far as just barrels in general, it looks like stainless steel barrels definitely erode much faster than chrome Molly from what it seems like WHEN discussing about AR GAS barrels in general

Not saying the barrel manufacturer fault as I’m sure they’ll make it right. I just wanted to try and understand barrels in general, and what’s normal and what is not.

I saw a picture of a barrel, the Gasport looked almost new and had over 2200 rounds… so not sure must’ve been a different type of metal

I also will add I did clean the barrel, not a massive clean job, but I still ran a carbon and a de copper through it, clean it fairly good and there appears to be quite a bit of copper left in the lands .
 

Attachments

  • IMG_2403.jpeg
    IMG_2403.jpeg
    327.6 KB · Views: 50
  • IMG_2396.jpeg
    IMG_2396.jpeg
    659.8 KB · Views: 51
  • IMG_2398.jpeg
    IMG_2398.jpeg
    677 KB · Views: 49
  • IMG_2399.jpeg
    IMG_2399.jpeg
    383.3 KB · Views: 41
  • IMG_2400.jpeg
    IMG_2400.jpeg
    726.7 KB · Views: 39
  • IMG_2401.jpeg
    IMG_2401.jpeg
    490.6 KB · Views: 42
  • IMG_2402.jpeg
    IMG_2402.jpeg
    610 KB · Views: 43
Last edited:
First reloads for the 6mm ARC using Barnes 105gr matchburners, Leverevolution, and winchester primers. Rounds were made on a dillon 550B, Lee dies, and a chargemaster link for the powder drop. I was kinda surprised that the 28.9 (top left), 29.4gr (bottom left), performed the best even though 29.7 had the best chrono numbers.

The 27.8gr charge of leverevolution is at the bottom right, 28.4gr is top right, 28.9 top left, 29.4gr bottom left, 29.7gr upper center.

AR Xcaliber 24" barrel 1-7t
 

Attachments

  • Screenshot_20240808_193448_ShotView.jpg
    Screenshot_20240808_193448_ShotView.jpg
    132.1 KB · Views: 52
  • Screenshot_20240808_193504_ShotView.jpg
    Screenshot_20240808_193504_ShotView.jpg
    131.6 KB · Views: 35
  • Screenshot_20240808_193543_ShotView.jpg
    Screenshot_20240808_193543_ShotView.jpg
    132.6 KB · Views: 31
  • Screenshot_20240808_193635_ShotView.jpg
    Screenshot_20240808_193635_ShotView.jpg
    132.9 KB · Views: 29
  • Screenshot_20240808_193741_ShotView.jpg
    Screenshot_20240808_193741_ShotView.jpg
    133.6 KB · Views: 33
  • 20240808_181528.jpg
    20240808_181528.jpg
    428.8 KB · Views: 35
  • 20240808_181601.jpg
    20240808_181601.jpg
    947.8 KB · Views: 53
  • 20240808_183223.jpg
    20240808_183223.jpg
    825.5 KB · Views: 51
Hi guys, I am new to the forum and am looking for some help or advice on the 6mm ARC. I have been lurking and trying to look for advice and recommendations. I am new with the 6mm ARC, but not new to reloading. I have been having some issues with accuracy and I would like to look at variables that could be causing some inconsistencies.

My upper is a 16” Faxon barrel (mid-length). It is in 1:7.5 twist. I am already thinking that my barrel might be my biggest variable. However, I was thinking that I would be able to at least break 2 moa at 100 yds with Hornady factory ammo (103, 105, 108gr). My average is greater than 2 inches. My reloads are even greater of a spread, like 4 inches or greater. Needless to say, I was quite disappointed. My reloading is using Varget and am doing this by measuring and double checking each load for grain accuracy. I have heard that there might be a preference for using Lever powder. Should this be a high consideration for me or is Varget good for the 6mm ARC?

So, while I have been reading so many other good things about different barrels that are more for precision, I am now looking to get a Proof carbon 18” barrel. I know that I could go longer. I am trying to keep my rifle a little versatile.

As I am writing this out and after reading so many posts, I am hoping that the Proof barrel will help me to get to where I want to be. My primary focus is truly target shooting. I am not a hunter. I love to reload and shoot my reloads. Super intrigued by the characteristics of the 6mm ARC.

Thanks for any advice!
 
  • Like
Reactions: rpoL98
Hi guys, I am new to the forum and am looking for some help or advice on the 6mm ARC. I have been lurking and trying to look for advice and recommendations. I am new with the 6mm ARC, but not new to reloading. I have been having some issues with accuracy and I would like to look at variables that could be causing some inconsistencies.

My upper is a 16” Faxon barrel (mid-length). It is in 1:7.5 twist. I am already thinking that my barrel might be my biggest variable. However, I was thinking that I would be able to at least break 2 moa at 100 yds with Hornady factory ammo (103, 105, 108gr). My average is greater than 2 inches. My reloads are even greater of a spread, like 4 inches or greater. Needless to say, I was quite disappointed. My reloading is using Varget and am doing this by measuring and double checking each load for grain accuracy. I have heard that there might be a preference for using Lever powder. Should this be a high consideration for me or is Varget good for the 6mm ARC?

So, while I have been reading so many other good things about different barrels that are more for precision, I am now looking to get a Proof carbon 18” barrel. I know that I could go longer. I am trying to keep my rifle a little versatile.

As I am writing this out and after reading so many posts, I am hoping that the Proof barrel will help me to get to where I want to be. My primary focus is truly target shooting. I am not a hunter. I love to reload and shoot my reloads. Super intrigued by the characteristics of the 6mm ARC.

Thanks for any advice!
Probably the barrel IF you can shoot 1-1.5 MOA with match ammo in .223 gas gun. Some people struggle with accuracy with a gas gun in general.
18” is perfect for a gas gun 6 ARC in my opinion. Especially if you suppress it. A few more fps with extra length doesn’t make sense honestly, unless shooting 800-1000 yds routinely. My Proof is close to 1 MOA with Hornady Black so…

Ballistic-X-Export-2023-03-21 15:57:25.810625.jpg
 
Last edited:
Hi guys, I am new to the forum and am looking for some help or advice on the 6mm ARC. I have been lurking and trying to look for advice and recommendations. I am new with the 6mm ARC, but not new to reloading. I have been having some issues with accuracy and I would like to look at variables that could be causing some inconsistencies.

My upper is a 16” Faxon barrel (mid-length). It is in 1:7.5 twist. I am already thinking that my barrel might be my biggest variable. However, I was thinking that I would be able to at least break 2 moa at 100 yds with Hornady factory ammo (103, 105, 108gr). My average is greater than 2 inches. My reloads are even greater of a spread, like 4 inches or greater. Needless to say, I was quite disappointed. My reloading is using Varget and am doing this by measuring and double checking each load for grain accuracy. I have heard that there might be a preference for using Lever powder. Should this be a high consideration for me or is Varget good for the 6mm ARC?

So, while I have been reading so many other good things about different barrels that are more for precision, I am now looking to get a Proof carbon 18” barrel. I know that I could go longer. I am trying to keep my rifle a little versatile.

As I am writing this out and after reading so many posts, I am hoping that the Proof barrel will help me to get to where I want to be. My primary focus is truly target shooting. I am not a hunter. I love to reload and shoot my reloads. Super intrigued by the characteristics of the 6mm ARC.

Thanks for any advice!
Sounds like standard Faxon stuff, assuming you are an experienced gas gun shooter.
 
I think if you're going to have just one 6ARC and plan to use it at the range more than anything else an 18" barrel is the best overall length. I love mine but I am getting the itch for something shorter for hunting now, I might have to build a 14.5" next.
 
Guys, thanks for the replies. I too am thinking that it is the barrel. I went ahead and have ordered the Proof 18” carbon barrel. Now, I can’t wait to build up another upper as well and get it to the range.

I have a couple of AR’s that I would consider a little more of a DMR. I was shooting one of them today at 100 yards with 62gr and 75gr 223 and my groups were so much better than my 6mm ARC results today. I do like gas guns. I also love a good bolt action as well.

It would be fun to take the 6mm ARC out further at some long range stuff. That is my plan.
 
Guys, thanks for the replies. I too am thinking that it is the barrel. I went ahead and have ordered the Proof 18” carbon barrel. Now, I can’t wait to build up another upper as well and get it to the range.

I have a couple of AR’s that I would consider a little more of a DMR. I was shooting one of them today at 100 yards with 62gr and 75gr 223 and my groups were so much better than my 6mm ARC results today. I do like gas guns. I also love a good bolt action as well.

It would be fun to take the 6mm ARC out further at some long range stuff. That is my plan.


18" Proof CF with factory Hornady 108's. They can definitely do it.

dTLPrtD.jpg
 
You can buy that seekins rail with barrel nut to go on any ar upper.... or you can buy the rail without the nut that goes on seekins irmt-3 upper. I've done both multiple times and have a few in the safe
Ah yes, thanks.
I’ve been using the IRMT-3 so long I forgot about that.
Those Megas are nice. Or at least used to be. I don’t know much about them after the ZEV takeover or whatever.
 
  • Like
Reactions: padom
Ah yes, thanks.
I’ve been using the IRMT-3 so long I forgot about that.
Those Megas are nice. Or at least used to be. I don’t know much about them after the ZEV takeover or whatever.

Yea me either. I stocked up on them cheap when the takeover was announced and places had inventory. I have a bunch of small and large frame MEGA sets. They are very nice
 
  • Like
Reactions: db2000
Good day gents. Have a questions about gas tube length. Is a +2 on a 22" barrel too much for the ARC? I'm getting short strokes with the bcg. Thanks for info in advance.
Shouldn't be, you just need to tune it. If its short stroking you either need more gas or less buffer weight maybe both. I bought the kak buffer kit "Link" and paired it with an adjustable gas block. I (think) am currently running a carbine weight buffer on my 24" +2 barrel with the aero adjustable gas block at about half open.
 
  • Like
Reactions: winxp_man
Shouldn't be, you just need to tune it. If its short stroking you either need more gas or less buffer weight maybe both. I bought the kak buffer kit "Link" and paired it with an adjustable gas block. I (think) am currently running a carbine weight buffer on my 24" +2 barrel with the aero adjustable gas block at about half open.
Solid info. I need to check the what I have for the buffer again. Cant remember. But it was on the lighter side. I was at one point thinking to drill the port a bit bigger. Would you happen to know much about the port sizes?
 
Solid info. I need to check the what I have for the buffer again. Cant remember. But it was on the lighter side. I was at one point thinking to drill the port a bit bigger. Would you happen to know much about the port sizes?
I don't. I just know that when I ordered my custom barrel I had to let them know I was going to use a adjustable gas block. I would only drill the gas port as last resort as I'm sure it won't be clear of burrs. You will inevitably see metal burrs sticking down into the bore and I have no idea how to get those out.
 
  • Like
Reactions: winxp_man
I don't. I just know that when I ordered my custom barrel I had to let them know I was going to use a adjustable gas block. I would only drill the gas port as last resort as I'm sure it won't be clear of burrs. You will inevitably see metal burrs sticking down into the bore and I have no idea how to get those out.

I know a few gunsmiths that have been doing AR barrels for a long time have a tool that looks like an upside down lollipop. After they drill the gas port they put that in the gas port hole to clean up the burs on the bottom side of the hole in the bore...
 
  • Like
Reactions: winxp_man
Good day gents. Have a questions about gas tube length. Is a +2 on a 22" barrel too much for the ARC? I'm getting short strokes with the bcg. Thanks for info in advance.
i have a 22" 6 ARC, rifle +2 gas length, gas port is 0.089". 4oz carbine buffer, USGI mil-spec M4 carbine spring, obviously a M4 carbine buffer tube. fixed (i.e. non-adjustable) gas block. cycles just fine, used the buffer weight to tune. solely non-suppressed.

it originally pin-gauged at 0.088", but i drilled it .001" to clean up the burr at the bottom of the gas port. Drill press, really sharp carbide drill, very slow on depth progress, cutting fluid. that worked, the drilled hole-end came out really clean. the going slow, I think, is the key, to not getting any flashing or dingle-berries or hanging chips or shavings at the bottom-end of the hole.
 
Last edited:
  • Like
Reactions: winxp_man
I know a few gunsmiths that have been doing AR barrels for a long time have a tool that looks like an upside down lollipop. After they drill the gas port they put that in the gas port hole to clean up the burs on the bottom side of the hole in the bore...
Tony Rumore indicated one of tools that did that job. I tried looking for it, seems to be made in jolly old England, sold to commercial or industrial or manufacturing entities "request a quote", no US on-line retail availability that I could find for the gas-port sizes. shucks.

Cogsdill Burr-Off
 
Tony Rumore indicated one of tools that did that job. I tried looking for it, seems to be made in jolly old England, sold to commercial or industrial or manufacturing entities "request a quote", no US on-line retail availability that I could find for the gas-port sizes. shucks.

Cogsdill Burr-Off
McMaster has the round ball burs that look like what this smith was using..


"Ball—For curved surfaces, round slots, and round-bottom holes."



Here another link to ball burs.. The 1/16 ball bur is probably what you want (0.0625")


 
  • Like
Reactions: rpoL98
My Craddock RTR 22" has a +1 Gas length
Same barrel but the +2 should have done +1 possibly. The issue presented itself when I run factory Hornady ammo I think it was the 108, 105 but the 103's where okay. Or other way around the 103, 105 where causing jams and 108's where find. I cant remember. I was out last this past winter. But will play the trick with the buffer and see what happends in addition to an adjustable gb.
 
i have a 22" 6 ARC, rifle +2 gas length, gas port is 0.089". 4oz carbine buffer, USGI mil-spec M4 carbine spring, obviously a M4 carbine buffer tube. fixed (i.e. non-adjustable) gas block. cycles just fine, used the buffer weight to tune. solely non-suppressed.

it originally pin-gauged at 0.088", but i drilled it .001" to clean up the burr at the bottom of the gas port. Drill press, really sharp carbide drill, very slow on depth progress, cutting fluid. that worked, the drilled hole-end came out really clean. the going slow, I think, is the key, to not getting any flashing or dingle-berries or hanging chips or shavings at the bottom-end of the hole.
Thanks for the info..... I think I will get it tuned just haven't had time to get to the range with the rifle. Will get to it this Nov when the heat dies down here in CA.
 
+2would be great for suppressed.
Factory ammo = will make less gas (just guessing)

Rolling your own will make more gas, if you make them spicy.

Running heavy bullets 106+ will also have more force to knock back the buffer.
 
Well, I went out yesterday again to see if I could figure this barrel out…

Put four port fat b. type port and it absolutely tamed the larger recoil I was getting….

I really concentrated on my fundamentals
Re-tightened everything

It just does not shoot the 87 gr Vmax

I did have one really good group with a believe. 106 or 108 ELD.

nearly 100 rounds and just does not want to group…. I started thinking it was my reloads,
But the Sd,s were around I believe 12.


i’m using a whiden die now, but I think the Hornady dies fucked up the cases by scraping and pushing brass causing a bell at the bottom of the case early on.

I did not chrono today so I was going by my previous results.

I did find when I was having really bad flyers when you get up to the 30.8 grains of levrevolution,.. I had to readjust the gas as it was opening too soon, causing the flyers… throwing them over 2 inches from where I was aiming. 3000fps+ And caused considerable marking to actually leaving a indentation on the plunger site.

Otherwise, the brass looks great, once adjusted the gas block =closing it down
 
Before you install the barrel you might want to use your bolt and some empty brass with the projectile of choice to find the lands.
1-One can always seat to the bullet long put a lot of your favorite imperial wax or hornady, or other lube, all over the bullet
2-shut the bolt
3-Take the round out ( obviously don’t put powder or primer in it)
4-set that round aside and mark with a black salt tip pen permanent “lands zero” and have that to set your bullet seater as your zero mark.

Can do that with each of your different bullets saves a lot of time and you know exactly where things are for measurements

For this reason, I love my Hornady click adjuster for bullet cedar that they just came out with absolutely awesome. I have those for my Hornady bullet cedars. I have two of them now.. it is the easy button for loading your rounds to whatever thousands of the lands are in the lands as you wish.
More than likely, you might need a mallet to tap on your charging handle to get the round out and even put the round in. I do it with the upper off that we have got clear access to my BCG

Take your measurement and that is your lands location

I just put the cartridge in my bullet seater back it off and then come down onto the top of the bullet until it touches and then click .020 thousands
 
1-One can always seat to the bullet long put a lot of your favorite imperial wax or hornady, or other lube, all over the bullet
2-shut the bolt
3-Take the round out ( obviously don’t put powder or primer in it)
4-set that round aside and mark with a black salt tip pen permanent “lands zero” and have that to set your bullet seater as your zero mark.

Can do that with each of your different bullets saves a lot of time and you know exactly where things are for measurements

For this reason, I love my Hornady click adjuster for bullet cedar that they just came out with absolutely awesome. I have those for my Hornady bullet cedars. I have two of them now.. it is the easy button for loading your rounds to whatever thousands of the lands are in the lands as you wish.
More than likely, you might need a mallet to tap on your charging handle to get the round out and even put the round in. I do it with the upper off that we have got clear access to my BCG

Take your measurement and that is your lands location

I just put the cartridge in my bullet seater back it off and then come down onto the top of the bullet until it touches and then click .020 thousands
Makes sense! Thanks for that info
 
Well, holy shit I went ahead and headspace my six arc barrel when I first got it and it did not close on the no go gauge..

closes easily on it now!

Was the bore not clean and something in the way , and I get a false reading?

after measuring the cartridges that came out of the gun, ===. 0.30 longer than new cases!!!!

Wtf?
I use plenty of lube even on the barrel lugs
I use lube, even on the bolt logs forward and rear logs get some form of lubricant

The loads were about 30 grains to 30.5 of leverlution.. max for a gas gun. These were Starling brass so they might punch out a little bit earlier before you hit that max charge, but I didn’t go over but maybe 10 rounds.approx..(and that was maybe half a grain or one grain over)
I’ll have to compare it to a new bolt but good God?

so either of the barrel lugs or the bolt started give way??

this is a Brownell’s six arc bolt.
I know a lot of guys use the JP bolts so somebody did not have the correct bolt steel heat treatment or the barrel lugs?

It would explain my shitty groups.

photo -you can see space between the caliper that is how much .30. Looks like!

what the heck?
 

Attachments

  • image.jpg
    image.jpg
    450.4 KB · Views: 23
Last edited:
I thought I didn’t have the proper tools until I saw one post that literally you can use an empty and Deprimed resized and then case trimmed 9 mm 10 mm 45acp, 44spc/mag ect to get a reading.

I purchased the Hornady headspace kit last week and added a bottom anvil, so I had a flat surface to check the headspace.

I didn’t think they were that far off least time?

Apparently, some people have an actual angle that matches the case head angle, some people just have a set up like Hornady and area419, they use a very sharp edge that touches the shoulder to get their dantum.

So now the question is: are all my cases trashed ?

Head spaced 0.30 over stock brass.

In a AR— makes use of a spring plunger.

Which forces a case forward, which then causes the shoulder to bottom out into the chamber, but the back end or the ass of the case is now free and spaced 0.30 from the bolt.

means the case will grow in the rear and not the front.

if the sides of the chamber hold the cartridge forward and not let it slide back, = and then you also have a spring plunger, shoving the case forward away from the boat face, only makes the case growth in the ass end more certain/ or at least highly plausible.

I believe there’s three ways that I could attempt to fix this wrong when the case is growing the wrong way you want the front shoulder to puff out not the ass end:

1- create a false shoulder so you size a little ways down the case after you don’t size the rest of it or you actually bring the shoulder out to the next size caliber up and size portion of that neck

2- you take the bullet and you make sure that it literally is jammed into the lands which acts similar to a false shoulder so the back of the case is touching very hard onto the bolt face

3- I could remove the plunger/ejector from the bolt. I think that’s the least desirable method because then you’re gonna have to literally take out each individual case what a pain in the ass. But it would do the same thing as the previous two methods because it allows the case to sit flush against the bolt face without the plungers, shoving it hard into the shoulder of the case into the barrel..

Otherwise, I’ve literally just ruined approx. 100 pieces of 3- time shot starline 6 ARC brass.

So I either will send the barrel back or I’ll just order up another bolt and take a measurement.

Probably easier to do the ladder

i’m thinking it might be the bolt but I don’t know it doesn’t look worn out and it doesn’t look like it’s had massive wear, but it’s really hard to visually check something and I don’t know what the bone stock measurements are supposed to be because again we’re dealing with measurements to the
0.000
 
Last edited:
Well, scratch that JP I’ll probably be the only bolt be able to get because Brownell’s bolt is out of stock. I contemplated getting three of them because you can literally buy three of them for the same price as a JP bolt and it’s advertised as the same steel as JP, obviously hardening processes may differ, but, I can’t imagine a bolt would be worn out, driven in pristine conditions on a bench cleaned after every session & oiled, lubed the lugs and all the load shots through the gun almost every single one of them were under max by 1 grain loads of the gas gun .

I never scraped or did anything to alter the lug depth. The only thing it did do was knock off the sharp edges of the barrel log so it didn’t wreck the cases and it was only done on the right side lugs, and never on the inside of the lugs only on the edges.

I’m actually relieved that I found out why the gun wasn’t shooting well.. it was getting in my head.
 
Well, scratch that JP I’ll probably be the only bolt be able to get because Brownell’s bolt is out of stock. I contemplated getting three of them because you can literally buy three of them for the same price as a JP bolt and it’s advertised as the same steel as JP, obviously hardening processes may differ, but, I can’t imagine a bolt would be worn out, driven in pristine conditions on a bench cleaned after every session & oiled, lubed the lugs and all the load shots through the gun almost every single one of them were under max by 1 grain loads of the gas gun .

I never scraped or did anything to alter the lug depth. The only thing it did do was knock off the sharp edges of the barrel log so it didn’t wreck the cases and it was only done on the right side lugs, and never on the inside of the lugs only on the edges.

I’m actually relieved that I found out why the gun wasn’t shooting well.. it was getting in my head.

Get the JP, start with the best, one less thing to worry about.
 
Yep Rainier Um x 2 due to soft extensions. Super corndogs also had the same issue x 2.
Reading @Kocher s post, I was thinking about those Ranier extension failures and wondered if maybe he was in the same boat?

If it really is a compressed bolt a opposed to a deformed extension, I've heard good things about the Rexus superbolt. Figured I'd give them a try if I ever had any issues with my toolcraft bolts.
 
Last edited:
  • Like
Reactions: Shoreglide
I went with the Rubber City bolt and Ive been using them and JP for a long time. RCA bolts and BCG's are top notch. Waiting for my mags to get here so I can go shoot this 6 ARC for the first time.

I have to say, Im skeptical on this cartridge and wonder if I made a bad decision building one. Time will tell...