New 6mm Advanced Rifle Cartridge

For those of you using the Berger 108gr Elite hunter projectiles with leverevolution in your gas gun what weights are working for you?
I need to do further testing. However, ~29.0 grs was showing promising results. Mag length restricts me to a min. of 60 thou jump (1.655" CBTO). I need to try 29.0-29.1 at different seating depths. I was getting around 2700fps. 20" Craddock Rock Creek 1:7.5.
 
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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.
Best take the upper off, clean up the barrel extention and get a good look at it.
 
I still have a few doubts but it seems as good if not better in terms of accuracy than 556 with factory match ammo and it has other advantages. It also allows me to walk away from large frame gassers as their advantages don't make up for their disadvantages in comparison, at least not for me personally. It has shorter barrel life than 556 sure, but we aren't talking 6Creed barrel life here.
 
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The barrel was a ready to rock craddock six arch barrel those guys have been fantastic to talk to when I’ve had questions via email and phone.

There’s no way for me to check at the moment by measurements if it’s the barrel lugs or the bolt lungs

I’m going to check my assembly process and make sure I didn’t do something goofy …

Not sure what you could do that would affect the headspace on the AR the bolt and rhe barrel …lugs

is almost idiot proof when it comes to how it goes together..
 
Heavy varmint bullets are what I like about the 6mm in general. A massive amount of bullet choices

6arc allows acces w/efficiant case design and semi-auto form.

I know I’ve been long-winded, but I’ve spent quite a minute of time trying to figure out what was going on with the rifle. I’m actually happy that I finally figured out why it had not been shooting.
 
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Cleaned everything up on the gun looked at the barrel lugs and the bolt lugs they both look fine

Perhaps it was always out of headspace from the start?

Ordering a new bolt now

I thought I read in an earlier post that you sent Craddock your bolt to headspace the barrel to? If so, did you reach out to them about the headspace issue? Maybe it was always wrong, and if not they should be able to tell whether it was an extension or bolt failure.
 
I appreciate the response guys….

Your input is very welcomed.



Addendum :: I never sent them my bolt as the barrels are already built.



I headspaced with a Go/NO GO guage. when I first built the gun. I don’t think I had a tool to remove the bolt ejector/Plunger… or maybe something was in the chamber to give it a false reading?


I was going to send my barrel out because it wasn’t shooting. I was told that it’s possible that I was not doing recoil properly… and I’m not the type of guy blame others
for issues, so I began to load and shoot…
Making sure that I had hit every tick in the check box before I sent it in

I had just found out the issue Thursday about the headspace.

I took everything apart. Wanted to make sure that it wasn’t something that I could easily figure out before I went to all that trouble ..

After some of the horror stories of shops, completely destroying someone’s handguard, or gas block by overtightening with gorilla hands or stripping things or misalignments and all kinds of goofy things….

sending a nice product that:
1: isn’t theirs doesn’t belong to them.
2: may not know anything about
Doesn’t make me feel a lot warm and fuzzy inside, so I’m not going to do it that way we’ll just get the barrel

$400in parts and then say it’s your problem not to mention you’re out the barrel as well. ?
I’m not claiming that the barrel manufacturer does this I just figure why take the risk?

A barrel manufacturer that makes AR barrels: they probably have parts to quickly assemble An upper .
doesn’t take long maybe 20 min ….15 min if barrel vice is setup already on the bench.

just because they know how to make barrels doesn’t make them experts on a geissele Handguard or a gas block, etc.

have to send the barrel out on Monday.

I wanted to try and quickly buy a new bolt and see if that would fix the issue but most don’t have it in stock, I might check some local stores..

It has been a learning experience
 
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I cleaned up the barrel extensions to pristine condition, including the bolt, and I looked down the barrel by both ends with a bore scope and I couldn’t tell if there was any wear on those barrel extensions. It sure didn’t look like it. Bolt looks perfect BUT Looks can be deceiving. ( the bolt head wear like any other normal AR 15 bolt.)

I had a bolt that was out of spec. Bolt looked fine didn’t look like there was any abnormal wear like scrapes, gouges, or uneven bolt lug edges. It was a aero precision AR 10 BCG (headspace was too long when checked with a no go gauge ) and that gunshot like this gun, and I couldn’t figure that out, until I got a GO/NOGO MEASURE GAGE, then finally head spaced it.

It was due to his previous experience. I made sure that I never shot another new rifle whether it’s a gasser or bolt again without head-spacing check, making sure within sami

I should’ve bought a set of brass head gauge insert set or made one out of empty handgun brass at the min. I would’ve seen that the brass was growing way too long..

instead, I just resized it until the bolt closed and there was my measurement.

In my experience, it seems like the only thing that I’ve had problems when it comes to AR 15 or AR 10 style rifles have been barrel/bolt headspace issues.

I built a M-16/ retro carry handle type rifle,
That 20” barrel chambered the NO-GO guage like a champ! Bolt closed on it straight from aero precision.

I had tried about five different bolts from different manufacturers to see if I could get it to headspace properly… aero precision had no problem taking the barrel back.

I have a hutch. It is the bolt that is the issue.
 
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how many rounds have you all put through your AR 15- chambered in 6 ARC?

I took an added up all of my rounds that were captured on the chronograph and then how many cases I had that were empty …as this last time I did not even shoot through the chronograph so I’m guessing I’m around 250 rounds on the 6arc
 
I am sitting somewhere between 200 and 300 rounds I believe, I'd have to go count empty brass to know for sure. I am just waiting for some free time and cooler weather to get back out there with all four Hornady factory loads and the chrono to do some more detailed testing. If I keep my current 18" barrel I believe I'll standardize on the factory 108's but I am feeling an overwhelming urge to get a Proof 14.5" and see what it likes best.
 
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I’ll say this cartridge has been fun. I have built several different precision AR’s the last few years and the ARC is without a doubt the best. No recoil, light, and sits between my 308 and 6.5 creed far as ballistics. This is the only 10 shot group I’ve done with it and with factory 108 eldm’s. I mostly just bang steel out to 900 yards (far as my range goes). I haven’t started loading for it yet. It’ll be in the hunting stand a lot this coming season.

3579347B-A003-4241-8D9E-05E3D65DCB7B.jpeg
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Yes, 87 grain 6 mm Vmax is going close to 3000 FPS … and staying within the Gas rifle load grains!
what’s not to like?

Yes, a six mil Creedmoor will go another 300+ FPS, but I don’t think it’s necessary to have all that recoil and powder burnt to do it.

I do not, however, think that the six ARC is LIGHT recoiling round. Especially, when comparing it to other light recoiling rifle rounds like a 17 Remington or 204 Ruger (running off a AR upper) with just an adjustable block and a heavy varmint barrel /w/o threads.

As those lighter bullets shoot just like a braked AR 15 shooting a 55.6 w/a 55 grain pill and a JP muzzle brake (recoil like a 22 long rifle bolt action )

most bolt action rifles that have been around for the last 100 years do not have an 3 or 4 port muzzle brake , or silencer on the end of them..



until I put a 4-port fat -b muzzle break (copy) on my 6-arc AR ( even had an adjustable gas block) This was NOT a light recoiling rifle!

I guess it comes down to physics= more mass to move from zero… the more recoil you’re going to feel.

That’s why the 17 Remington or the 17 556 .. very light recoil, even without a muzzle device

I may purchase a 17 556 just because the barrel is a great price and it works well and you don’t have to mess around with those expenses 17 Remington brass!.. these are the recoil kings when it comes to AR 15 uppers
 
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well boys, I finally figured it out after a long drawn out process of trying to figure out why this barrel wasn’t shooting …..

you have to take out the ejector plunger when checking the headspace with a go or no go gauge!!!!!

If you do not remove it, you’ll get a false reading

When I pulled the plunger, I checked and behold, the go gauge went no problem. In fact, a brass piece that was about 010 Over head Space chambered easily.

I’m sending this barrel back to Cradic precision. I’m sure they’re findings will be the same as mine.
 
I can’t stress enough for my experience to check your case growth on your cases when they come out of the gun it’ll tip you quite quickly as if there’s a problem with headspace

It’s the first thing I should’ve purchased when I bought a gun and reloading equipment

I have an AR 10 that I didn’t group well. I checked on that and that is 016 that’s correct so looks like this is also suspect it’s from a different manufacturer.


Very important to pull the ejector plunger out of the bolt when checking headspace
Otherwise, I’ll give you false reading
 
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I loaded up 50rd last night with 87 VMAX to get some initial rounds down this new 22" RTR barrel..

I used CFE223 which is the closest powder to Lever I had on Hornady reloading data for 87 VMAX. I dont have any Lever and just trying to get some rounds down this barrel so this will work for now. Ive seen a few people getting really good results with 87 VMAX/CFE223 in the 29.5 - 31.0gr range.

I loaded up 10rd each 29.8, 30.1, 30.4, 30.7 and 31.0

We will see how it goes..
 
I loaded up 50rd last night with 87 VMAX to get some initial rounds down this new 22" RTR barrel..

I used CFE223 which is the closest powder to Lever I had on Hornady reloading data for 87 VMAX. I dont have any Lever and just trying to get some rounds down this barrel so this will work for now. Ive seen a few people getting really good results with 87 VMAX/CFE223 in the 29.5 - 31.0gr range.

I loaded up 10rd each 29.8, 30.1, 30.4, 30.7 and 31.0

We will see how it goes..
Let us know how it goes. Going to be loading some 87's here shortly. Had good luck with H4895 and Berger 87 VLD's back in the day with the 243 LBC. Haven't tried the 87's in the ARC yet.
 
Let us know how it goes. Going to be loading some 87's here shortly. Had good luck with H4895 and Berger 87 VLD's back in the day with the 243 LBC. Haven't tried the 87's in the ARC yet.

H4895 was the next closet powder to Lever on Hornady 87 vmax reloading data for 6 ARC after CFE223..

I'm not using my H4895 for 6 ARC. Too hard to find to waste on 6 ARC. It's my.go to 6BR powder
 
Just got back from putting the first rounds through this 22" RTR 6 ARC @ 100yd. I will start out by saying it impressed me way more than I expected.

I shot the first 5rds to get a rough zero and tune my gas which was stupid easy. Im using the Rubber City adjustable gas BCG which is my go to favorite over an adjustable gas block for a few years now. I started it off all the way in then backed out 1 full turn. I shot 2 rounds that both locked back on empty mag then the 3rd didnt lock back. I opened the gas key 1/4 of a turn more and shot 47 problem free rounds all locking back on empty mag. That was the extent of tuning my gas. hahah

After I shot these first 5rd out of the gun i proceeded to shoot for groups with each charge weight. First charge 29.8gr I only had 5 left so I shot a 5 shot group but all the rest I shot 10 shot groups with and they really surprised me.

I pulled a few shots going to fast but all in all, Im very happy and cant wait to continue load development now that I have a starting point.

Ill probably play around with 31.0gr with the other 50pcs of virgin brass I have primed. Probably load up 3 batches 31.0gr and play with seating depth a little and see how they do and go from there. 31.0gr was the highest I tested today and ZERO pressure signs... Pictures below of the brass. Not a mark on the case head, nice round primers.



Here is the first 5 shots out of the gun tuning the gas. shot to the right out of the group is shot #1 out of the brand new barrel and the next 4 were into a 0.5" group....


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Here the load testing target. first group far left 29.8gr is 5 shots, all the rest are 10 shots..



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Here some pictures of the brass. The 2 pics of case heads are from the hottest charge I tested, 31.0gr looks absolutely perfect.



wZlIbAE.jpg


wrey3xs.jpg


E8pVG40.jpg
 
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Looking at the burn rate chart, PP 2000MR is right next to Lever and just a tad slower that CFE223.

I have 10-12lb of PP 2000MR I'm not using for anything. Gonna work up some loads with it and see how velocity/pressure/accuracy compares to CFE 223


 
I need to do further testing. However, ~29.0 grs was showing promising results. Mag length restricts me to a min. of 60 thou jump (1.655" CBTO). I need to try 29.0-29.1 at different seating depths. I was getting around 2700fps. 20" Craddock Rock Creek 1:7.5.


I finally was able to focus on my notes and put this together on my target with the burger 108gr Elite hunters. The 28.4gr group wasn't bad just low on velocity where as the 29.4gr was just a bit bigger and right were I want to be velocity wise out of the 24" barrel. At seated depth of 2.252-2.260" COL (the tips vary so I use the comparator number of 2.650") I am .085 from the lands. With the duramags it seams like I have some wiggle room to go longer? Kinda tempted to seat them at COL of 2.275" for a .070" jump if it fits in the mag. Other wise I'm tempted to seat them a little deeper for .090 and .095 jump. Just not sure which way to run because as you'll see below the other two bullets seam to like being .050"-.060" off the lands.
20240901_160333.jpg




This target shows my Barns 105gr matchburners on the right, and the hornady 108gr ELD on the left. The Barns were jumped .050" and did not like it compared to my first test with had them at .060". So I'll load them up again at .060" and .065" just to see. The Hornadys were interesting. The factory ammo shots about 1"-1.5" groups but they have a .045" jump. These were tested at .050" and I'm tempted to try them again at .055" and .060" to see if they tighten up even more.

20240901_160320.jpg
 
I went to the range yesterday to shoot my setup once again. I had a great first impression with it and was hoping to have a similar experience as the last one. I was a little disappointed. Despite the Proof barrel, I was not seeing consistency. It was not as bad as previous attempts.

I know that some people have said that finding consistent accuracy from a gas gun, can be a challenge. I am seeing that to be the case.

So, here are some thoughts or questions on what has worked well for you guys.

1) How long do you typically wait between shots? I know that a warm to hot barrel to affect accuracy. Thoughts?

2) discussion on BCG here recently. Currently am using a Faxon Arms. I have looked into JP, but they are out of stock. I also have an AR Stoner milspec BCG. Have not tried that out. Thoughts on my setup with Faxon Arms? Could be a variable, right? I do plan to buy one once available to try it out

3) adjustable gas block. Should I have one for the 6mm ARC?

4) shooting with a suppressor. I have been using a suppressor and it seems to work fine. However, I took it off and there was not enough back pressure to cycle the rifle. I thought that was weird. Hence my question on adjustable gas block

5) what buffer weight are you finding to be the best? Currently using an H1

I will try it all out again here soon to see if the results change or what.

Thanks again!
 
I finally was able to focus on my notes and put this together on my target with the burger 108gr Elite hunters. The 28.4gr group wasn't bad just low on velocity where as the 29.4gr was just a bit bigger and right were I want to be velocity wise out of the 24" barrel. At seated depth of 2.252-2.260" COL (the tips vary so I use the comparator number of 2.650") I am .085 from the lands. With the duramags it seams like I have some wiggle room to go longer? Kinda tempted to seat them at COL of 2.275" for a .070" jump if it fits in the mag. Other wise I'm tempted to seat them a little deeper for .090 and .095 jump. Just not sure which way to run because as you'll see below the other two bullets seam to like being .050"-.060" off the lands.
View attachment 8492603



This target shows my Barns 105gr matchburners on the right, and the hornady 108gr ELD on the left. The Barns were jumped .050" and did not like it compared to my first test with had them at .060". So I'll load them up again at .060" and .065" just to see. The Hornadys were interesting. The factory ammo shots about 1"-1.5" groups but they have a .045" jump. These were tested at .050" and I'm tempted to try them again at .055" and .060" to see if they tighten up even more.

View attachment 8492604
Your groups are kind of like mine. I too am working with factory Hornady loads and reloads, both with 108gr bullets. I hope that you find success in tightening those up. Good luck and keep us posted.
 
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Your groups are kind of like mine. I too am working with factory Hornady loads and reloads, both with 108gr bullets. I hope that you find success in tightening those up. Good luck and keep us posted.

Ya we'll see how things go Thursday at the range. But here's what the Barns 105's did for me on the 1st outing with two tight groups half a grain apart. I truly believe it's in the bullet seating that gonna make or break it.
20240901_162953.jpg



As for your question about buffer and adjustable gas block. It depends on a few things. What's your barrel length and gas system length? Where is your brass ejection at when suppressed? But being as your gun won't cycle without the suppressor you would need a lighter buffer to function. However if you keep the lighter weight and try to use the suppressor then you will probably be over gassed.
 
I went to the range yesterday to shoot my setup once again. I had a great first impression with it and was hoping to have a similar experience as the last one. I was a little disappointed. Despite the Proof barrel, I was not seeing consistency. It was not as bad as previous attempts.

I know that some people have said that finding consistent accuracy from a gas gun, can be a challenge. I am seeing that to be the case.

So, here are some thoughts or questions on what has worked well for you guys.

1) How long do you typically wait between shots? I know that a warm to hot barrel to affect accuracy. Thoughts?

2) discussion on BCG here recently. Currently am using a Faxon Arms. I have looked into JP, but they are out of stock. I also have an AR Stoner milspec BCG. Have not tried that out. Thoughts on my setup with Faxon Arms? Could be a variable, right? I do plan to buy one once available to try it out

3) adjustable gas block. Should I have one for the 6mm ARC?

4) shooting with a suppressor. I have been using a suppressor and it seems to work fine. However, I took it off and there was not enough back pressure to cycle the rifle. I thought that was weird. Hence my question on adjustable gas block

5) what buffer weight are you finding to be the best? Currently using an H1

I will try it all out again here soon to see if the results change or what.

Thanks again!

Sample size of one here with a single 18" Proof Carbon build and roughly 200-300 rounds of experience with this caliber so take this with a grain of salt. So far it has grouped well with factory loaded 108's, 103's grouped just under 1" and the 80's have been all over the place but I did have a group under 1". See pic below for best five-round group with the 108's.

  1. I shoot five round groups in roughly one minutes time, so 15-20 seconds between shot. I typically don't shoot more than 5-10 rounds without allowing the barrel to cool down for at least five minutes.
  2. I have run a JP bolt in a LMT SA carrier with great results and I have run the full JP FMOS BCG as well. I haven't noticed any changes in performance with the full JP BCG but the round count with it is still sub 100.
  3. Some swear by the need for an adjustable gas block but there have been wide selections in gas lengths which definitely creates another variable that can have an impact here. I believe Proof has the gas lengths the most sorted of any manufacturer currently making 6ARC barrels. I am running a non-adjustable SLR Micro on mine and have no issues suppressed.
  4. I had the same experience with the 80 VT's specifically without a can but it was simply to test for shift. I think most will shoot the 6ARC suppressed so it's not an issue in my eyes.
  5. With my 18" Rifle +1 I have beening a Carbine buffer but I could see moving up to an H1 as I go shorter. Lot's of variables here, just play with your particular setup until you find what works best.


dTLPrtD.jpg
 
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Have had very good success with the Berger 95 classic hunting bullet in my GAP-15. Not the highest BC bullet but very accurate. It's design allows you to seat at the lands, easily stay under mag length, and keep the bullet above the neck/shoulder junction. 31.2 gr lever in a 22" barrel with lapua grendel brass = right at 2900fps.

I've heard it said and definitely experienced it..... this cartridge seems to really tighten up at the top charges. I would start load development with a quick ladder test just to find pressure and check ES/SD, I suspect you'll find things best toward the top and youll know where to focus. I havent really found good "low nodes". SD's are crazy good with leverevolution.

87 vmax shot awful for me. Not sure why but I won't even give it another chance. 109 hyb shot decent, big jump at mag length.

Factory hornady ammo shot decent for me on paper, under MOA usually, but had really large velocity spreads and shot like shit at long range. Kind of frustrating as I didn't want to reload for 6arc, factory ammo was like $21 a box when I had the rifle built and I wanted at least 1 rifle I could just grab a few boxes and go shoot! Owell.
 
Took my 6ARC out for the first time this weekend. LMT MARS upper/lower. Proof 18" CF barrel converted by D. Wilson. Kahles 318i. Geissele SSA-E. JP bolt. I only shot factory Hornady Black 105 BTHP. The gun flat shoots. 2642fps with 3.5SD from factory ammo in an 18" barrel. Zeroed in 3 shots then took it out to 591 (4mils) . The range only goes to 640 and it was bloody hot out, so I called it a day. Smacking small steel targets was too easy from prone on bags. I know I've only scratched the surface - looking forward to a real test with the rifle soon.
 
I scrubbed my 6 ARC clean this morning after the first 50rd put through it the other day. Loaded up a seating depth test going longer as well and tested 10rd each of 2 higher charge weights of CFE 223... 31.3gr and 31.6gr.


The original seating depth I tested the other day is just hammering. Going longer just opened up the groups but the first 2 groups going longer were still 0.75moa.

This is the first 5 shots out of the cold clean gun. The high shot was the 1st shot out of the clean cold bore then the next 4 went into this 0.25moa group.

Im done with CFE223 and 87 VMAX. This load is great.


31.0gr CFE 223
87 VMAX
New Starline brass
CCI 450
2.143" COAL / 1.635" Ogive
2882.3 - ES 9.7 SD 3.9


22" RTR


wqhZo2J.jpg



Here the numbers on the 2 higher charge weights I tested. Again, not a mark on the case head, primers still nice and round, no pressure.


10 shots each


31.3gr - 2919.6 - ES 32.8 SD 8.3


REiQ9lX.jpeg





31.6gr - 2960.6 - ES 52.5 SD 14.8



CTGkYzF.jpeg
 
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Can I just stick a stainless Proof barrel in my current 223 receiver and have a pretty decent gun?

Bolt, barrel, mag, that's all that's needed.

Also, Ive read mixed reviews on what mags work with 6 ARC.

Just to give some feedback here, Ive been running an ASC SS mag and I have had zero issues. Feeds great, runs great.

I've been running DuraMags with zero issues. I have a Geissele mag here that I have yet to try.
 
Bolt, barrel, mag, that's all that's needed.



I've been running DuraMags with zero issues. I have a Geissele mag here that I have yet to try.

I saw Geissele had 6 ARC mags the other day. I planned to buy one if I had any problems with these ASC SS mags. I read people saying the ASC 6 ARC mags were nothing but problems.

I've got lots of SS ASC mags over the years and never had a single issue with any of them. Same goes for these 6 ARC mags. So no need to buy a geissele for me.
 
I consider JP and Rubber City the best. I've been shooting both for a long time.. I'm shooting the Rubber City bolt with their adjustable gas BCG in my 6 ARC

Here the 6 ARC bolt which uses a 6.5 Grendel bolt

 
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I saw Geissele had 6 ARC mags the other day. I planned to buy one if I had any problems with these ASC SS mags. I read people saying the ASC 6 ARC mags were nothing but problems.

I've got lots of SS ASC mags over the years and never had a single issue with any of them. Same goes for these 6 ARC mags. So no need to buy a geissele for me.
Same. ASC SS 6.5 Grendel with blue followers have worked fine for me. They’re 10 rounders in a Seekins frame.
 
Here’s 108 ELD-M factory performance from my Seekins 18” Proof CF 1:7.5

9/4/24
72F 40% 30.36in

Hornady 108 ELDM
2504, 2506, 2480, 2472, 2445
2505, 2492, 2488, 2480, 2463
2498, 2517, 2511, 2513, 2510
2479, 2511, 2487, 2508, 2494
SD 18.5 ES 72 2” group
 
I think someone at Horndady is smoking meth! Decided to see what the max charge of 33.6gr of leverevolution looked like in the case and well.... there is no freaking way a 75gr vmax is gonna fit with the powder half way up the neck. The base of the vmax sits almost down to the beginning of the shoulder.
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So I poured some out till I got below the neck and came up with 31.7grs which looks like this...
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To top it off the recommended COL of 2.095" is jammed into the lands on my gun.