New 6mm Advanced Rifle Cartridge

[Stevenhansell]

This thread has been very informative. I’ll say I love the rifle. Built mine with a Ballistic Advantage 18” rifle gas. Extremely accurate to 100 with Hornady match. Shot a doe at about 75 yards last night with the ELD-M and I’m pleased with performance. Now if the dies would get here I’m all set to start reloading it.

 

[George Mac]

Can anyone help with the pros/con of a 16” or 18” barrel for a 6 ARC build (AR not Bolt). How much distance will 50 fps make before dropping into the transonic range? I’m not a hunter just so it will be for target shooting and maybe competition.

Just relocated to Western North Carolina and am looking for ranges or places in the mountains to stretch the rifles out on steel.

Assuming a 16” barrel and factory 108 ELD-M’s, I put a 2500fps MV into the Shooter App, but I just don’t believe the results I’m seeing. A 108 ELDM @2500fps with a 3500DA shows it is supersonic out to 1230yards? Have I messed up my inputs somewhere or is that a realistic expectation?

 

[ormandj]

Can anyone help with the pros/con of a 16” or 18” barrel for a 6 ARC build (AR not Bolt). How much distance will 50 fps make before dropping into the transonic range? I’m not a hunter just so it will be for target shooting and maybe competition. I put a 108 ELDM into the Shooter App with a 2630/2600 MV, but I just don’t believe the results I’m seeing.

Just relocated to Western North Carolina and am looking for ranges or places in the mountains to stretch the rifles out on steel.

Use the Hornady 4DOF calculator, in 4DOF mode. I get 2643fps from a 18” Bartlein with 108 ELD-M with the factory ammunition. 1200fps is the “safe” spot, below that and depending on conditions you may encounter weirdness. Just do a table every 100yds with velocity and see what you want.

 

[George Mac]

Ormanj, Do you mind posting a table of your results at your DA. I’d like to compare it (entering the same MV/DA) to see if I’ve somehow messed up my inputs or data? Thank you.

 

[ormandj]

Sorry, on the road, so a mobile shot. This is with an 18” barrel. Are you not using 4DOF? I highly suggest it over shooter app, especially with Hornady bullets with radar derived drag models.

 

[godofthunder]

I read basically this whole thread and searched it as well, couldn't find anything so I'll ask:

Is anyone shooting the Berger 87gr VLD Hunting out of this? I'm looking at putting one of these together and think I'd like to stick in the 75-90gr range. Main use for coyotes, secondary use would be deer for my kid when she's old enough.

 

[Parham4020]

If anyone else is interested, I asked LMT if they had plans to make a 6 ARC barrel and they said, not at this time. While I’m not surprised, given their current backlog, I was hoping one was in the works.

 

[LongRangeAggie]

I read basically this whole thread and searched it as well, couldn't find anything so I'll ask:

Is anyone shooting the Berger 87gr VLD Hunting out of this? I'm looking at putting one of these together and think I'd like to stick in the 75-90gr range. Main use for coyotes, secondary use would be deer for my kid when she's old enough.

What's wrong with the 95gr classic hunter? https://www.snipershide.com/shooting/posts/8659277

I plan on trying this bullet and the 108 Elite Hunter with LVR. My Craddock Rock Creek should be getting here by end of week.

 

[godofthunder]

What's wrong with the 95gr classic hunter? https://www.snipershide.com/shooting/posts/8659277

I plan on trying this bullet and the 108 Elite Hunter with LVR. My Craddock Rock Creek should be getting here by end of week.

Nothing at all. I was more thinking I could run the 87gr VLD for deer and 87 vmax for coyotes and not have to worry much about POI difference at 100 yds. The 95gr classic hunter looks good though, especially with those numbers in the post you linked. I would be shooting an 18" barrel, so slightly slower, but still good velocity.

 

[Leftie]

If anyone else is interested, I asked LMT if they had plans to make a 6 ARC barrel and they said, not at this time. While I’m not surprised, given their current backlog, I was hoping one was in the works.

I'm glad that I wasn't the only person interested in an LMT MRP-pattern barrel for this cartridge. I think that, if 6 ARC continues to show such promising results, it could be a really solid option (especially if they provided it with a BCG made by them). I'm curious what the threshold for such a "custom order" would be, although I don't think that it would be anything less than a mid 5-figure number for the barrels alone. The bolts and bolt carrier groups would likely be even more (pure conjecture regarding both).

If you haven't checked out Nefarious Arms or D. Wilson Manufacturing, they will likely be able to convert a 6 ARC AR barrel from nearly any manufacturer to work in an LMT monolithic upper with no problems. I'd email them and find out.

While I can't speak personally for either of their work, I do know that they offer this service, and others appear to have had great results - I've just not heard of it having been done with 6 ARC, yet...

Hope this helps.

 

[eugevita]

This thread has been very informative. I’ll say I love the rifle. Built mine with a Ballistic Advantage 18” rifle gas. Extremely accurate to 100 with Hornady match. Shot a doe at about 75 yards last night with the ELD-M and I’m pleased with performance. Now if the dies would get here I’m all set to start reloading it.

Awesome! I also purchased a 18" BA barrel! hopefully mine will also shoot well! What sort of MV are you getting with the 108ELDM? Also are you using an adjustable gas block? If so which one? Thanks!

 

[godofthunder]

Awesome! I also purchased a 18" BA barrel! hopefully mine will also shoot well! What sort of MV are you getting with the 108ELDM? Also are you using an adjustable gas block? If so which one? Thanks!

Question wasn't directed at me, but the Aero Precision gas block looks nice and is also reasonably priced.

 

[Stevenhansell]

Awesome! I also purchased a 18" BA barrel! hopefully mine will also shoot well! What sort of MV are you getting with the 108ELDM? Also are you using an adjustable gas block? If so which one? Thanks!

I’ve got the standard non adjustable gas block that came with it. Haven’t shot with the magnetospeed yet but will try to this weekend.

 

[Bantam1]

Question wasn't directed at me, but the Aero Precision gas block looks nice and is also reasonably priced.

I have one on a 16” Rainier 223W barrel and I am happy with it. They made a running change so make sure the adjustment part is the bronze colored one. The stainless one doesn’t close all the way or something like that. I have another on the way for my 6ARC build.

 

[jbailey]

Technical data point on 6ARC gas port size for 'long' gas systems:

BACKGROUND:
I had short-stroking issues in my 20" Rifle +2 length gas system. Couldn't solve with mag changes, different lowers, ultra light weight buffers, different springs, different loads, different gas blocks, etc.

Finally, I measured the gas port: it was 0.085ish". I got some great advice from fellow members @Constructor and @357Max that 0.085ish" was likely too small for this gas system length. @Constructor recommended 0.095ish".

SOLUTION:
@357Max was kind enough to offer his skills and his lathe to drill out the port to 0.095ish". Luckily he is about 45minutes away, so I drove up and he drilled it out in under an hour.

I returned home and back to the range. I set the gas block to the middle of the adjustment range and bang, first shot, beautiful 3:30 injection and locked back bolt - first time ever! Opened block one more click and bang, 3:00 injection and another locked back bolt. Then tried a 10 rd loaded magazine: 100% cycled, locked bolt and all rounds landing 3:00 o'clock. Perfect.

CONCLUSION:
0.095ish" is the recommended gas port size for long gas systems.

Huge thanks to @357Max and @Constructor - you guys get gold stars from me!

 

[LongRangeAggie]

A work of art

 

[Rumblestrip]

 

[Capri_Man]

A work of art

Indeed! But who made it and how many flutes?

 

[LongRangeAggie]

Indeed! But who maked it and how many flutes?

Rock Creek blank. Chambered, threaded and fluted by Craddock Precision.
It has 9 flutes.

 

[LRRPF52]

Didn’t know GAP was doing a 6mm ARC AR-15. Way cool.

GAP knows how to build a super-accurate gas gun. There are things that they’ve known how to do dating way back that really fine-tune a gas gun’s accuracy and reliability.

I don’t recall any malfunctions with the .308 or .260 Rem gassers they’ve built for me, with one exception.

I had a weird incident where .260 Rem bounces brass off the ejection port door before it could open fast enough, and go back into the port.

Chris Kyle said he had the same issue with the SR-25 Mk.11 Mod 0. I think a stronger ejection port door would fix that on the large frame guns, but very few people see it because they are normally shooting with an open port door.

I sent them DPMS receivers, BCG, small parts, rifle RET, BCM CH, JP Handguard, basically everything but the barrel, and they hooked my builds up before there was a GAP-10.

Placed 2nd with the .308/Obermeyer pipe rifle in a military International Team Sniper Competition in Europe. My partner was shooting a .25-06 AICS with Berger VLDs.

Something like 6mm ARC would be perfect for those events, since there is a lot of movement through terrain between stages, a speed orienteering course with all your rifles, ammo, optics, and gear, and stages with trenches, obstacles, etc.

 

[John Burns]

About 1/2 dozen of these deer were taken with the 6MM ARC.

Works fine but so does a 5.56MM or a 6MM Creedmoor.

Looks to be a good choice in a 16 inch suppressed AR to offer a bit more bullet weight.

 

[godofthunder]

About 1/2 dozen of these deer were taken with the 6MM ARC.

Works fine but so does a 5.56MM or a 6MM Creedmoor.

Looks to be a good choice in a 16 inch suppressed AR to offer a bit more bullet weight.

What bullet was used? Any info on terminal performance, distances shot, etc?

 

[LongRangeAggie]

About 1/2 dozen of these deer were taken with the 6MM ARC.

Works fine but so does a 5.56MM or a 6MM Creedmoor.

Looks to be a good choice in a 16 inch suppressed AR to offer a bit more bullet weight.

Cool pic. What's the deal with those tiny suppressors?

 

[Chase214]

Anyone shot any 95 gr tmk through a 20 or 22 inch barrel just wandering what kind of velocities your getting

 

[Chase214]

Has anyone compared the older leverevolution ( metal lid) with newer plastic lid

 

[Yondering]

Has anyone compared the older leverevolution ( metal lid) with newer plastic lid

I've been shooting Lever for a handful of years but don't think I've ever had any with a metal lid, sorry. The different batches I've used over the years seem to be remarkably consistent, in my experience. Or maybe I've gotten lucky, dunno.

 

[westcoasteast]

Just a three shot group, but it proved to hold close on a subsequent ladder test then ran out to 500 ringing 12 down to 4 inch plates with each. Proof carbon fiber 18inch barrel, vltor billet upper, adjustable gas block, geissele rail, surefire rc2 762 can, factory hornady ammo. Had planned to reload with cfe but looks like I’ll be getting some leverevolution now too.

 

[newageroman]

Just got 500 more cases of Starline to convert
I also just ordered more 105 VLDs to go in them. I was hoping to snag some 105 HTs but they were out of stock because I snoozed... I feel pretty good about making these work though.

I went ahead and loaded up100+ of the 105 HTs that I DO have on hand last night over some LeverLoution in the middle of my best nodes, which run about 2600. Will most likely be next year before I can try thos out on longer targets.

I also have a few hundred 105 Boat Tail Target bullets to try as well.

I'm working on getting the Dillon setup to pump these out. Right now its a manual powder drop/confirm/trickleup, then seat on the Dillon using shellplate #1 The rounds fall off the plate when indexed unless I go very slow. Need to check Dillon site and see what plate is suggested for Grendle cases.

 

[Yondering]

Why are you trickling Lever? Just dump the exact charge to start with. That’s one of the big advantages of ball powders like this that meter so well.

 

[dankcincy]

Hello all.
New to the reloading game and have been playing with the 6Arc.
I have read through the entire post. lots of good info
I was wanting to try the heavier bullets, 109-115 so I picked some up and starting testing, keeping an eye on my brass.
I'm using CFE223 and Leverevolution, Hornady Brass, and Federal GM205M AR Small Rifle Match Primers
Ar-15
16" Proof Barrel, 7.5 twist.
My documentation is a bit sloppy but getting better.
Edit:
I'm trying to share a google doc but it doesn't seem to be working right.
Okay....for whatever reason if you're viewing it online it doesn't show some of the stuff but if you download it you can see it all.
Thoughts?

ShootersCalculator.com | 109 Berger

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

www.shooterscalculator.com

6Arc Tests.xlsx

drive.google.com

 

[newageroman]

Why are you trickling Lever? Just dump the exact charge to start with. That’s one of the big advantages of ball powders like this that meter so well.

Using the manual powder drop and still see +/- .1 grains variance on some rounds. Honestly I'm good with it, as resetting the tray on the scale fixes it most of the time, so I just ran them. I hand trickled up a couple rounds but for this set of ammo its nitpicking so I just load them. That's what I LOVE about this powder (ball powders) they flow like water!. There were a couple of charges that I saw +.2 grains, which I just dumped back in the top and went again.

 

[tasty_chicken]

@dankcincy nice velocity numbers for a 16" barrel. Are you running a carbon or steel? What about elevation and temperature when you are shooting?

 

[trdjohn]

...seat on the Dillon using shellplate #1 The rounds fall off the plate when indexed unless I go very slow. Need to check Dillon site and see what plate is suggested for Grendle cases.

dillon shell plate A according to their chart, was just looking at this the other night

 

[dankcincy]

@dankcincy nice velocity numbers for a 16" barrel. Are you running a carbon or steel? What about elevation and temperature when you are shooting?

SS barrel, I forgot about the carbon barrel they make.
The indoor range I'm shooting at is at around 580ish ft.
It's pretty chilly around here at the moment. 30s and 40s.
The ammo stays indoors except for the trip to the range which as mentioned is an indoor range so the ammo stays above 65° or so.
I would like to try something more temp stable but finding powder at the moment is a bit impossible or ridiculously overpriced as all in here are probably aware.

 

[tasty_chicken]

SS barrel, I forgot about the carbon barrel they make.
The indoor range I'm shooting at is at around 580ish ft.
It's pretty chilly around here at the moment. 30s and 40s.
The ammo stays indoors except for the trip to the range which as mentioned is an indoor range so the ammo stays above 65° or so.
I would like to try something more temp stable but finding powder at the moment is a bit impossible or ridiculously overpriced as all in here are probably aware.

Thanks for the info. Can't wait to get my 18" Proof build started.

 

[dankcincy]

Thanks for the info. Can't wait to get my 18" Proof build started.

Np
The 16" easily gets hits on a 12x12 out to 1000yrds with factory ammo.
It's not super consistent though. The ES on the Hornady is just too much.
You'll go over, adjust, and then under.
Best strategy I found with the factory loads is to just hold on and take the hits you can get. Lol

 

[godofthunder]

Np
The 16" easily gets hits on a 12x12 out to 1000yrds with factory ammo.
It's not super consistent though. The ES on the Hornady is just too much.
You'll go over, adjust, and then under.
Best strategy I found with the factory loads is to just hold on and take the hits you can get. Lol

Makes me question if I should go 16" instead of 18". I was planning on 18" because I like that length and a little extra velocity never hurt anyone, but it will mostly be a coyote gun with hopefully some shooting out to 1k down the road.

 

[dankcincy]

Makes me question if I should go 16" instead of 18". I was planning on 18" because I like that length and a little extra velocity never hurt anyone, but it will mostly be a coyote gun with hopefully some shooting out to 1k down the road.

If that's what you already have in mind then you probably ought to stick with it.
Otherwise you'll always question the decision. Just my . 02

 

[ormandj]

Makes me question if I should go 16" instead of 18". I was planning on 18" because I like that length and a little extra velocity never hurt anyone, but it will mostly be a coyote gun with hopefully some shooting out to 1k down the road.

Go 18” if 1000yds is in the cards and you want reliable hits. Any less and depending on conditions even with the best powders for velocity and you’ll be entering the transonic zone. It’s still a short and handy rifle.

 

[PoorFarmer]

Do you handload it? If so, What’s the case capacity? Is this a “varget” cartridge?

Not sure on h2o capacity but I’ve been running 35ish grains of leverrution. From what I’m hearing from others they‘re getting good results with varget.

 

[dankcincy]

Go 18” if 1000yds is in the cards and you want reliable hits. Any less and depending on conditions even with the best powders for velocity and you’ll be entering the transonic zone. It’s still a short and handy rifle.

According to Shooters Calculator these loads are super sonic past 1300yrds with a 16" barrel. It shows that even factory 108s are good past 1200yrds. Am I missing something?
EDIT: I had the wrong velocity numbers in for the 108s. With the correction it appears that they run out of steam shortly after 1000yrds or so.

ShootersCalculator.com | 108, 109

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

www.shooterscalculator.com

 

[westcoasteast]

According to Shooters Calculator these loads are super sonic past 1300yrds with a 16" barrel. It shows that even factory 108s are good past 1200yrds. Am I missing something?

ShootersCalculator.com | 109 Berger

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

www.shooterscalculator.com

With the data and my current groupings I’m good just shooting factory ammo for a while

 

[dankcincy]

With the data and my current groupings I’m good just shooting factory ammo for a while

How much luck are you having finding it?

 

[westcoasteast]

How much luck are you having finding it?

Been able to find a box here and there...ima catch heat for this one

 

[dankcincy]

Been able to find a box here and there...ima catch heat for this one

LMAO!!!
I thought about doing that. I had a store chain local to me that was stocking it with no limits.
I did end up with 500pcs of brass from the factory ammo.

 

[westcoasteast]

LMAO!!!
I thought about doing that. I had a store chain local to me that was stocking it with no limits.

I just put in for “notify when in stock” on 8-9 websites and for about 6 months if I got the email I purchased 100-200 rounds

 

[LongRangeAggie]

Technical data point on 6ARC gas port size for 'long' gas systems:

BACKGROUND:
I had short-stroking issues in my 20" Rifle +2 length gas system. Couldn't solve with mag changes, different lowers, ultra light weight buffers, different springs, different loads, different gas blocks, etc.

Finally, I measured the gas port: it was 0.085ish". I got some great advice from fellow members @Constructor and @357Max that 0.085ish" was likely too small for this gas system length. @Constructor recommended 0.095ish".

SOLUTION:
@357Max was kind enough to offer his skills and his lathe to drill out the port to 0.095ish". Luckily he is about 45minutes away, so I drove up and he drilled it out in under an hour.

I returned home and back to the range. I set the gas block to the middle of the adjustment range and bang, first shot, beautiful 3:30 injection and locked back bolt - first time ever! Opened block one more click and bang, 3:00 injection and another locked back bolt. Then tried a 10 rd loaded magazine: 100% cycled, locked bolt and all rounds landing 3:00 o'clock. Perfect.

CONCLUSION:
0.095ish" is the recommended gas port size for long gas systems.

Huge thanks to @357Max and @Constructor - you guys get gold stars from me!

Doubt it, but were you using a suppressor?

I shot my CP Rock Creek 20" rifle +2 with standard carbine buffer/spring, adjustable gas block and my Silencerco Omega on it this past Sunday and it shot great. I emailed Paul Craddock last week asking what size he uses for the gas ports and he told me he uses 0.086". I was using factory Hornady 108s. Time only allowed for 8 shots.

Next time I take it out I will try it w/o the supp on and see if I have any issues and report back.

 

[jbailey]

Doubt it, but were you using a suppressor?

Negative. Only using the brake supplied by manufacturer. My gas port was 0.085" and went up to 0.095" with the problem solved.

 

[ormandj]

According to Shooters Calculator these loads are super sonic past 1300yrds with a 16" barrel. It shows that even factory 108s are good past 1200yrds. Am I missing something?

ShootersCalculator.com | 109 Berger

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

www.shooterscalculator.com

Yes, an accurate calculation. Here’s calculations on my 18” with my Labradar measured velocity with factory 108 ELD-M:



You can see somewhere between 1000 and 1100 yards it drops below 1200FPS which is where all the funky things start to happen to bullets as they cross the transonic boundary. Also, keep in mind this is just for the conditions I measured locally, you want some headroom for various environments.

Also, try 4DOF or Applied Ballistics, they really are the best ballistic calculators. I’ve always had spot on results from them when trued to my rifles and loads; not so much on the others. The above is using a drag curve determined via radar, not a simple BC which has been proven to not be consistent across multiple velocities. G1 is awful, and G7 isn’t the answer either.

 

[dankcincy]

Yes, an accurate calculation. Here’s calculations on my 18” with my Labradar measured velocity with factory 108 ELD-M:

View attachment 7509567

You can see somewhere between 1000 and 1100 yards it drops below 1200FPS which is where all the funky things start to happen to bullets as they cross the transonic boundary. Also, keep in mind this is just for the conditions I measured locally, you want some headroom for various environments.

Also, try 4DOF or Applied Ballistics, they really are the best ballistic calculators. I’ve always had spot on results from them when trued to my rifles and loads; not so much on the others. The above is using a drag curve determined via radar, not a simple BC which has been proven to not be consistent across multiple velocities. G1 is awful, and G7 isn’t the answer either.

I double checked my testing numbers and I did have too high of a initial velocity in for the 108 on Shooters Calculator. I still had an estimate in there and hadn't updated it since testing. I ran it again and it does appear that the 108 starts to have issues shortly after 1000yrds
That would explain what I was seeing when I was shooting out to 1100yrds.

ShootersCalculator.com | 108, 109

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

www.shooterscalculator.com