6mm ARC "sane" loads ?

[moorepower]

That's Great... and I thought I was the only one guilty of doing this. Welcome to the "I Didn't Mean To Be A Dick" Club. Our membership is continuing to grow, our ranks are filled with the Technologically Challenged. If you were born before 1975 then your automatically a member!!!!

Without tone or body language, the choice of words or even sentence structure can easily be misunderstood. It is not uncommon for me to read a post I made previously and realize I need to hit "Edit" in order to clean up my message and/or possibly rearrange a couple of words to eliminate the inadvertent/unintentional Jackwagon undertone.

I was old enough to know better in 1975.

 

[243Mendoza]

4 out of approx 90 cases.....I also have a 243 lbc that I formed 200 Lapua cases for with no case loss, so I have the process figured out, only difference is .030 more setback on shoulder of arc...besides, forming the case is mostly the neck resize...rsbhunter

So you are setting back the shoulder of 6.5 Grendel brass .030". I always wondered how difficult would be such a large setback?

 

[Ray123]

I didn't anneal the new brass , this was all new , unfired, formed brass.Base to datum was set .003 off of fired factory brass measurements using Hornady comparator and .350 insert, bullets .020 off touch. Fired other loads and no scratches at all. Yes, those are cracks ! The feed ramps were polished with Dremel polishing compound and a "bullet" tip polishing tip....mirror finish, smooth edges, corners. Fired 40 rnds of factory Hornady Black....slight pressure signs, but no scratches, cracks, etc. ???? rsbhunter

I used Starline basic brass to form 6mm arc...had to anneal before and after each sizing operation...or they crack down the middle just like what appears in your picture. I know cause I tried one without annealing it cracked, the only ine I lost cause I got lazy and thought I'd try it without annealing first...I got the answer on my first try.

 

[Ray123]

So you are setting back the shoulder of 6.5 Grendel brass .030". I always wondered how difficult would be such a large setback?

No problem on Starline 6.5 grindel brass, very easy ...hardy know the difference. Done a thousand. Now ...Starline basic 6.5 straight wall start by annealing first, then neck to 30 cal, trim, then anneal, then neck down anneal to 6 5, then anneal, then neck down to 6 arc anneal repeat. PITA... with all the dies and all the annealing I did 250 cases, it all works and shoots great...the way to go is the Starline 6.5 grendel brass....not the 6 5 basic, unless its all you can find.

 

[Bill K]

Who put these AR's together ? You or a gunsmith ? Sounds like maybe a issue with gas block and/or a headspace issue.
For the bulge on the base/brass, you need to resize with a small base die for semi-autos.

 

[pmc847]

I’m into my load development for my AR15 6mm ARC Bartlien 26” 7.25 twist by Paul Craddock.
I’m resizing 6.5 Grendel using L E Wilson bushing FL die. I also anneal my brass.
Here is what I’ve observed.

SAAMI specs cartridge .4410 @ .200 from base and .4315 @ 1.00 from base
specs chamber .4426 @ .200 from base and .4325 @ 1.00 from base.

Hornady 108 match ammo
cartridge .4350 @ .200 from base and .4275 @ 1.00 from base.

Fired bras
cartridge .4425 @ .200 from base and .4320 @ 1.00 from base.

Resized with L E Wilson die
cartridge .4350 @ .200 from base and .4250 @ 1.00 from base

Measurements taken with Mitutoyo CD-6" ASX to the best of my ability.

Question is, is this die re-sizing the body too much? I am getting the shoulder bump I need and use Short Action headspace comparator with datum B .350 insert for measurement..

Shouldn't, ideally, resizing be the same as SAAMI cartridge spec. It seems that the difference from fired brass and resized brass of .0075 is a lot. I know ammo manufactures need to have adequate clearance for all platforms but I’m looking to load for my specific rifle. My 223 Wylde resize the brass no more than .0025.

Talked to John Whidden and he said the 6ARC at .0075 is way too much and my 223 at .0025 is about right (maybe could be a little tighter) even for gas guns.

So, could the problems discussed here be caused by over sizing brass, actual resizing compared to SAAMI spec of .4410? Try measuring your fired brass to your resized brass.

Check out Whidden Gunworks custom dies and his videos.

By the way, standard dies setup is to have the die hit the shell holder which doesn't give you any leeway if you have to bump the shoulder back more were as Whidden dies are made to be setup with a gap between die and shell holder thus giving better range for shoulder bump.

Just my 2cents worth. YMMV.


Philip

 

[GetReal]

I converted Norma 6.5 Grendel brass. (Hornady brass is garbage. Had loose primer pockets after 1 firing)

28.6 LVR
105 Berger HTs
450CCI
1.686 to BTO
1.188 base to shoulder

Running about 2600 FPS from 20" Bartlein 1:7

Always under 0.75" sometimes 0.5" No pressure signs.

 

[rsbhunter]

That sounds like a good load...alot of the "book" loads showed 30gr + with 105's....and yes, they were for ar's. I think like alot of things, people wanted the 6 ARC to be something it never could, nor wasn't designed to be. My next project might be a 22 Grendel, the matches I shoot are only out to 500 meters, so it will do what I need in an AR platform... rsbhunter

 

[JimSC]

I have found that a 90 gn high BC bullet gives me better performance with lower pressures(<50K according to GRT) than the 105/107's. I have been playing with AR Comp, LvrEvo, and ACC 2520. I am still in the early test stage but initial results are looking promising.

 

[GetReal]

That sounds like a good load...alot of the "book" loads showed 30gr + with 105's....and yes, they were for ar's. I think like alot of things, people wanted the 6 ARC to be something it never could, nor wasn't designed to be. My next project might be a 22 Grendel, the matches I shoot are only out to 500 meters, so it will do what I need in an AR platform... rsbhunter

Yeah.....6 ARC is a medium range / velocity cartridge.

I shoot 224 V outta a 26" bolt gun, and I can run with the 6.5 CM and hotter cartridges well past 600 yd.

 

[rsbhunter]

GetReal, as in alot of cases, the purpose of the cartridge was over run by the marketing hype, and there's always keyboard commando's that add fuel to the fire.....as you stated, it's a great cartridge for it's intended purpose... rsbhunter

 

[David Milisock]

GetReal, as in alot of cases, the purpose of the cartridge was over run by the marketing hype, and there's always keyboard commando's that add fuel to the fire.....as you stated, it's a great cartridge for it's intended purpose... rsbhunter

True, true true! The 6MM ARC certainly can be used in bolt rifles in ways not intended but in most of those cases there are better options.

It was intended as a special purpose cartridge in the AR/M4 platform. In the roll it is in its own league. I carried the M2 Carbine in the M1A1 configuration and in close it was very good. The CAR 15 and the M4 were improvements but not anything close to my 6MM ARC. The AR/M4 platform allows modern (force modifiers) but has issues with energy on target, significantly at range. The same platform chambered in 6 MM ARC can now carry a short barrel and reach out better than a standard M4 or mount a 20" barrel and accurately reach out well past the old M 16 A2.

Comparing my Aero Precision M4E with a 16" barrel to my M1 Carbine with an 18" barrel in a tactical configuration both weigh around 7 3/4 pounds. Recoil from from the 6 MM ARC is less even with both rifles wearing muzzle brakes.

The Aero in 6MM ARC is vastly more accurate, 1/2" at 100 yards, out past 600 yards with iron sights, hitting 1/2 sized steel all the time. It pushes a high BC 105 factory load at a clocked (10 FT from muzzle) 2,600 FPS, versus the 30 Carbine pushing a 110 RN at 2050 FPS with a realistic maximum accurate range of 200 yards.

More energy, more reach, better accuracy, less recoil, I waited 50 years and I'm happy.

 

[barefooter56]

Me and a friend have built 6 arc ar's. And knowing that the pressure is lower on the gas guns, followed some Hornady and other published load data. Problem is, that by the time we reach even mid level loads in any given bullet weight, the brass is taking such a beating, or producing a "belt" on the base of the case, they are not reloadable. We each have a 24" bbl of the same mfg, and he has a second different mfg. Both of these bbls are from reputable mfg's, so just curious what others are seeing on CFE,Leverevoloution , RL 15, or any powder, with 95gr Bergers, 105 Bergers or Hornady, or 108 ELD-M bullets....Thanks for any help or advice... rsbhunter

You can contact the BERGER BULLET support team at: Support@capstonepg.com for 6 ARC GAS GUN load data using BERGER BULLETS or VV POWDERS . 8AM TO 4:30PM EASTERN TIME MON thru FRI.

 

[gunsandgunsmithing]

True, true true! The 6MM ARC certainly can be used in bolt rifles in ways not intended but in most of those cases there are better options.

It was intended as a special purpose cartridge in the AR/M4 platform. In the roll it is in its own league. I carried the M2 Carbine in the M1A1 configuration and in close it was very good. The CAR 15 and the M4 were improvements but not anything close to my 6MM ARC. The AR/M4 platform allows modern (force modifiers) but has issues with energy on target, significantly at range. The same platform chambered in 6 MM ARC can now carry a short barrel and reach out better than a standard M4 or mount a 20" barrel and accurately reach out well past the old M 16 A2.

Comparing my Aero Precision M4E with a 16" barrel to my M1 Carbine with an 18" barrel in a tactical configuration both weigh around 7 3/4 pounds. Recoil from from the 6 MM ARC is less even with both rifles wearing muzzle brakes.

The Aero in 6MM ARC is vastly more accurate, 1/2" at 100 yards, out past 600 yards with iron sights, hitting 1/2 sized steel all the time. It pushes a high BC 105 factory load at a clocked (10 FT from muzzle) 2,600 FPS, versus the 30 Carbine pushing a 110 RN at 2050 FPS with a realistic maximum accurate range of 200 yards.

More energy, more reach, better accuracy, less recoil, I waited 50 years and I'm happy.

I appreciate your perspective and why you like it so well but where terminal performance is concerned, I think most people on here worry more about how it performs on target and possibly game than on a human being. I suppose that aspect has its place too but it's one that I hope I never have to worry about. In that event though, I'm a reloader and have several 6 Grendel barrels and components. Other than the availability of factory 6 ARC loaded ammo, I see nothing that the ARC does better, if as well as the very slightly larger 6 Grendel. I also have 30 Major(grendel) bbls and components for impressive CQB(is that the right term) performance. In a gas gun, I shoot 125s at 2650 from a 18" bbl without pressure issues due to the larger bore and hence, expansion area. I can push it a little harder but in my own testing while developing that cartridge in 2007, I settled on that speed as a safer max than what I could get if I pushed it a little harder with select components that may or may not shoot quite as well, but built pressure and velocities a bit better. That testing is how I knew before (possibly) the first ARC was produced that the speeds they were advertising to sell more guns, was very much MAX for the AR15 platform and that bolt failure was likely rather than vaguely possible, over time and with the nature of people to push the envelope a bit. Again though, I can appreciate your perspective...it's just not at the top of my list of attributes for the aforementioned reasons. Thank you for your service!! The ARC does have an audience and a market area that it fills well. I think it's a shame that they didn't just use Grendel brass and case dimensions rather than introducing something different that requires more components and equipment, and still doesn't quite have the same performance as a 6 Grendel does. I don't fault Hornady so much for that though, as I'm familiar with the attorney that claims rights to a straight 6 Grendel(6AR) cartridge. It was likely done to work around him more than any other reason. I think they overcomplicated it and left some performance on the table due to him...just my opinion. And yes, I've dealt a bit with him too. He's still never told me the difference in (his) 30 AR and my 30 Major, but claims it has his design and that it's a different cartridge. I've also been told he wouldn't know how to turn a lathe on, yet he can work a pencil when it comes to claiming design work as his own. I strongly suspect that's why there is a 6 ARC at all and why it could've been even better. All of the above mentioned cartridges will perform at a much better level in a bolt gun, though.

 

[David Milisock]

I appreciate your perspective and why you like it so well but where terminal performance is concerned, I think most people on here worry more about how it performs on target and possibly game than on a human being. I suppose that aspect has its place too but it's one that I hope I never have to worry about. In that event though, I'm a reloader and have several 6 Grendel barrels and components. Other than the availability of factory 6 ARC loaded ammo, I see nothing that the ARC does better, if as well as the very slightly larger 6 Grendel. I also have 30 Major(grendel) bbls and components for impressive CQB(is that the right term) performance. In a gas gun, I shoot 125s at 2650 from a 18" bbl without pressure issues due to the larger bore and hence, expansion area. I can push it a little harder but in my own testing while developing that cartridge in 2007, I settled on that speed as a safer max than what I could get if I pushed it a little harder with select components that may or may not shoot quite as well, but built pressure and velocities a bit better. That testing is how I knew before (possibly) the first ARC was produced that the speeds they were advertising to sell more guns, was very much MAX for the AR15 platform and that bolt failure was likely rather than vaguely possible, over time and with the nature of people to push the envelope a bit. Again though, I can appreciate your perspective...it's just not at the top of my list of attributes for the aforementioned reasons. Thank you for your service!! The ARC does have an audience and a market area that it fills well. I think it's a shame that they didn't just use Grendel brass and case dimensions rather than introducing something different that requires more components and equipment, and still doesn't quite have the same performance as a 6 Grendel does. I don't fault Hornady so much for that though, as I'm familiar with the attorney that claims rights to a straight 6 Grendel(6AR) cartridge. It was likely done to work around him more than any other reason. I think they overcomplicated it and left some performance on the table due to him...just my opinion. And yes, I've dealt a bit with him too. He's still never told me the difference in (his) 30 AR and my 30 Major, but claims it has his design and that it's a different cartridge. I've also been told he wouldn't know how to turn a lathe on, yet he can work a pencil when it comes to claiming design work as his own. I strongly suspect that's why there is a 6 ARC at all and why it could've been even better. All of the above mentioned cartridges will perform at a much better level in a bolt gun, though.

My concept for my 6MM ARC was and still is as a general purpose rifle in an AR only. The AR does very well as a working rifle in many environments outdoor and indoor. Being old school I'm a firm believer that every man needs one rifle that fits a self defense and medium game hunting role.

The 6MM ARC in an AR works as a general purpose working rifle, self defense if needed, taking medium game at reasonable ranges if needed. It fits in an ATV, a Jeep or in a scabbard on horse back. Even the 30 Carbine has been used to take game and historical records show brown bear taken with an M1 Carbine. Is that nuts or what?

It's certainly not my only rifle but I've built one to have a state of the art GP rifle. I prefer to carry it with 5 round magazines for easy carry and handling. I carry the 24's but in 50 years I never needed more than 1 or 2.

To say that the 6MM ARC is more than what I've described is in my opinion reachiing a bit. I certainly would never tell anyone not to play around with it, it's America after all.

What is important is that a man can readily buy factory ammo, reloading supplies and tools because it's an adopted cartridge. I love wildcats but not for a working tool.

 

[rsbhunter]

As I said, I have sold off the 6mm ARC, and kept the 243 LBC. The 243lbc is the 6.5 grendel necked down. It was alot better than the arc, in my case. I am loading the hornady 105gr hpbt with 30.5 gr of a popular "lever" gun powder and getting great velocity (2800fps) and under moa @100. This is out of an ar15 with Craddick Precision parts and a Patriot Valley Arms barrel.....rsbhunter

 

[pmc847]

I'm curious whether you have shot any of the factory Hornady 108gr ELD-M loads in your 6mm ARC?

Some report these to show pressure.

My personal experience is that they shoot without issue. In fact, 2743 fps and sub 0.75 MOA (hard to beat with handloads). To me, I think it helps to set a baseline for performance with factory ammo that is loaded to 52K PSI pressures. If your AR shoots with pressure signs with this ammo it may be a dwell time issue related to gas, premature bolt opening, mass, spring or other timing related issue with your rifle. Mine is a 24" bbl, 1:7.5 twist, with +2 gas and a Superlative adj gas block.

re5513
Just came across this and was wondering what buffer and spring are you using? What is the weight of your buffer and what is you gas block set at?

I have a similar set up. 26" 1:7.25, +2, Superlative adj gas block. working on load development. having lock back issues. took all the weight out of the buffer (rifle length) and gas block all the way open. switching to carbine buffer (adjustable) and flat wound spring (with spacer). Have't tested yet. Sure would like to get the timing and lock back right.

Cheers

Philip