New 6mm Advanced Rifle Cartridge

trob_205

Gunny Sergeant
Belligerents
Jul 11, 2013
808
507
99
Coldwater, MI
At the moment Hornady will not admit they are going to do it. There are no gauges, dies, brass or ammo. I could have a batch of barrels in 60 days but I'm not going to produce barrels until all the other parts are out there.
Excuse my ignorance in not knowing that was you! And I don’t blame you. Makes me wonder if it was supposed to be an NRA release or something and are waiting for a big show release for it after this covid stuff settles down?
 

shoot4fun

Gunny Sergeant
Belligerents
Oct 27, 2003
4,072
490
189
Riverside, Alabama, USA, etc
6 Grinch has been around a while now, mostly in the BR game. I've seen where some were shooting it in short-range and some in 600 YD matches.
It is made from Grendel brass. From Bart's Bullets website:
1. What is the Grinch.

The 6MM Grinch is the brain-child of father and son team Dean and Brett Stroud of Cape Girardeau Missouri. The Grinch is a 6.5 Grendel case blown out to a 40° shoulder and neck down to 6MM.


40° shoulder may not feed reliably in the AR platform?
 

Constructor

Private
Belligerents
Excuse my ignorance in not knowing that was you! And I don’t blame you. Makes me wonder if it was supposed to be an NRA release or something and are waiting for a big show release for it after this covid stuff settles down?
Could be, just never know about big companies. Some will test the crap out of things and only release when they know it's right and others will come up with an idea and start advertising parts the next day...with no testing.
I've been shooting a 6mm based on a Grendel case since 07. First it was the Banshee, then 6mmAR then my Predator. I recognize the diameters and freebore on that print, it should shoot.
 
Last edited:
  • Like
Reactions: trob_205

BluntForceTrauma

Private
Belligerents
Aug 5, 2014
9
4
6
No doubt Hornady was planning on making an official, public announcement of the 6mmARC at the NRA Show in Nashville — until it was cancelled over Covid19. And now I'm guessing they're waiting out the whole Covid19 thing.

IF Hornady releases the 6mmARC, it's gonna be a 224 Valkyrie killer — despite the 224V being a very good design in itself.

Why?

SAAMI spec for 224V lists a 90gr @ 2,700 fps.

SAAMI spec for 6mmARC lists a 108gr @ 2,700 fps.

Berger's classic 6mm 105gr Hybrid has a 0.536 BC.

Berger’s new .224 85.5gr Hybrid has a 0.524 BC.

Berger’s new 6mm 109gr Hybrid has a 0.568 BC.

Both of those bullets — to Berger's credit — are amazing bullets.

Launched at roughly the same muzzle velocity, however, there’s no way the lower BC bullet is gonna catch the higher BC bullet.

If a competitor is looking for every little edge at long range in an AR, the 6mmARC has it.
 

dms416

Sergeant
Belligerents
Jan 12, 2014
390
57
34
Central IL
No doubt Hornady was planning on making an official, public announcement of the 6mmARC at the NRA Show in Nashville — until it was cancelled over Covid19. And now I'm guessing they're waiting out the whole Covid19 thing.

IF Hornady releases the 6mmARC, it's gonna be a 224 Valkyrie killer — despite the 224V being a very good design in itself.

Why?

SAAMI spec for 224V lists a 90gr @ 2,700 fps.

SAAMI spec for 6mmARC lists a 108gr @ 2,700 fps.

Berger's classic 6mm 105gr Hybrid has a 0.536 BC.

Berger’s new .224 85.5gr Hybrid has a 0.524 BC.

Berger’s new 6mm 109gr Hybrid has a 0.568 BC.

Both of those bullets — to Berger's credit — are amazing bullets.

Launched at roughly the same muzzle velocity, however, there’s no way the lower BC bullet is gonna catch the higher BC bullet.

If a competitor is looking for every little edge at long range in an AR, the 6mmARC has it.

No doubt from a ballistic standpoint, hell yeah! Hornady knows how to roll out a new cartridge (good, bad or ugly).

Technically speaking, JP has an enhanced bolt so that's covered but what of reliable magazines/feeding? Hopefully there is also a better initial handle on barrel/gas system lengths than with the Valk too.

Inevitably guys are also going to do the Bolt/AR combo for various reasons...hopefully it translates over better than trying to build a .224 Valk bolt gun. At the very least barrel blanks would be easier to source.
 

Constructor

Private
Belligerents
John I'm betting it is going to hurt the Grendel too. Those guys that shoot long range targets and varmints/yotes will get much better exterior ballistics out of this 6mm.
Best combo in the Valkyrie is 80gr ELDs at 3000fps using h4895, G1 BC of .485 (same as 6.5 123) but 350fps faster than the Grendel.
 
  • Like
Reactions: Lightning8

tomcatfan

Sergeant
Belligerents
Nov 22, 2010
582
281
69
36
Southern MD.
IF Hornady releases the 6mmARC, it's gonna be a 224 Valkyrie killer — despite the 224V being a very good design in itself.
This is how I see it. If this thing does get buy in from Hornady, I would convert one of my AR’s over in a heart beat. 224V never blew my skirt up. I have a RPR 556 that I shoot out to 1000 yds with. Spotting can get tricky at distance, I would rather shoot my 6.5 or better than that, my 7mm SAUM at distance. A 6mm would be a little more reasonable compared to a 224 IMO.
 

BluntForceTrauma

Private
Belligerents
Aug 5, 2014
9
4
6
Young Manufacturing also has an enhanced bolt, as well as JP, but any standard Grendel bolt will work. Been working for something like 16 years now and still on the rise.

Any Grendel magazine will work.

Question is, would the market want 6mmARC bolts with a 0.136 boltface counterbore (which I call Mk136) or 7.62x39 bolts with 0.125 boltface (which I call Mk125)? I'd recommend Mk125 for the slightly greater bolt body strength.

6mmARC would probably cut into 65G sales a bit, I'd guess, but nowhere near what it would do to 224V.

6.5 Grendel is the multi-purpose F6F Hellcat of the AR world and this 6mmARC is like the F8F Bearcat dedicated interceptor. :cool:
 

Yondering

Sergeant
Belligerents
Mar 16, 2017
574
196
49
Skagit Valley, WA
No doubt from a ballistic standpoint, hell yeah! Hornady knows how to roll out a new cartridge (good, bad or ugly).

Technically speaking, JP has an enhanced bolt so that's covered but what of reliable magazines/feeding? Hopefully there is also a better initial handle on barrel/gas system lengths than with the Valk too.

Inevitably guys are also going to do the Bolt/AR combo for various reasons...hopefully it translates over better than trying to build a .224 Valk bolt gun. At the very least barrel blanks would be easier to source.
It's not like the Grendel and all of it's wildcats haven't been worked out in the AR15 a long time ago. All of the points you bring up have been well established, and are frequently discussed on this site and several others. This 6mm ARC is nothing really special or new in that regard; bumping the shoulder back .030" doesn't change much other than to be different than existing wildcats.
 

dms416

Sergeant
Belligerents
Jan 12, 2014
390
57
34
Central IL
It's not like the Grendel and all of it's wildcats haven't been worked out in the AR15 a long time ago. All of the points you bring up have been well established, and are frequently discussed on this site and several others. This 6mm ARC is nothing really special or new in that regard; bumping the shoulder back .030" doesn't change much other than to be different than existing wildcats.


True, but people that experiment and wildcat are a bit more used to tweaking/bending/cutting and finding solutions. They're stubborn people that make things work. Once you leave the mindset of a place like this and get out into the dregs of commercial end user expectations its a whole other animal. I'm talking the "why won't my Mk18 digest Tula ammo???" people that want their cake, want to eat it, and want it yesterday.
 
  • Like
Reactions: Constructor

Yondering

Sergeant
Belligerents
Mar 16, 2017
574
196
49
Skagit Valley, WA
True, but people that experiment and wildcat are a bit more used to tweaking/bending/cutting and finding solutions. They're stubborn people that make things work. Once you leave the mindset of a place like this and get out into the dregs of commercial end user expectations its a whole other animal. I'm talking the "why won't my Mk18 digest Tula ammo???" people that want their cake, want to eat it, and want it yesterday.
That's true, but the Grendel is not a wildcat and uses the same magazines. The other points you brought up for the wildcats are ironed out well enough already that there doesn't need to be any experimenting, other than normal load development. We know how they feed, what gas systems to use, what bolts to use, how to form brass, etc; all that stuff that wildcatters normally have to tinker with and "figure out" is already done.

Take the 243 LBC for example - it's a regular production item from Columbia River Arms (and they have a 30% off sale right now too FYI). You can buy off the shelf reloading dies and components, and basically treat it the same as a standard Grendel. The only real difference is the lack of mainstream factory ammo. These have been done so thoroughly that they barely even count as wildcats any more; if a guy wants to pretend he's a wildcatter without really putting any effort into it, these are the easy choice right now.

Sure, if Hornady introduces this they'll do it right and it'll become a lot more popular, but the point is that it's already been done, A LOT, and there's not really anything left to figure out and tinker with like there would be with a true wildcat.

I predict this 6mm ARC is going to be a repeat of the 6.5 Creedmoor phenomenon, where we've got a group of people who've been using essentially the same thing for 10+ years while the general uninformed masses go nuts about this latest new thing they read about in a gun rag. They'll talk about how new and innovative it is, and wonder if xx works, or if yy works better, and so forth without understanding that it's not new at all, just the latest thing to go mainstream. Of course there will be the "260 Remington" group too, who insist the new cartridge is dumb and gay, and their 6x6.8 or whatever is just as good while ignoring the benefits of a cartridge that works well with long sleek bullets.
 

Cajuntransplant

Learning all I can...
Belligerents
Feb 23, 2017
73
44
24
SDakota
I know I’m excited about it cause I don’t prefer to neck size down brass or wildcat things. And if it’s picked up from Hornady then dies and brass will be readily available and when it’s mainstream it’ll be less expensive as well. Love my 6.5 grendel and love the heavy 223 and I’m excited to get another upper done up if this comes through.
 

Bantam1

Private
Belligerents
Nov 18, 2008
174
130
49
USA
When I was at SHOT I spoke to my contact at Hornady. This was developed for some military requirement and test. He said the test rifle was an AR with a Proof barrel. Proof also chambered the barrel. He said they were getting good barrel life out of it and testing "went really well". I walked over to Proof and they didn't want to acknowledge it...so not sure how far away this is from coming to the public.

When I got back home I tried to find info on this and nothing came up. Then last week the drawing came out. I was really interested when we discussed the capability and performance they were seeing.
 
  • Like
Reactions: dms416

Ledzep

Chancellor
Belligerents
Jun 9, 2009
2,437
1,512
219
NE
That's not uncommon for Proof. Stuff on their military side is pretty quiet.
 

cleric

Private
Belligerents
Nov 13, 2011
472
133
49
38
Dallas, tx
I was looking at an ar platform for shooting some distance. I was debating some of the 6mm wildcats, but I will hold up and wait and see what this has to offer
 

Gtscotty

Sergeant of the Hide
Belligerents
Minuteman
Jul 22, 2018
270
226
49
When I was at SHOT I spoke to my contact at Hornady. This was developed for some military requirement and test. He said the test rifle was an AR with a Proof barrel. Proof also chambered the barrel. He said they were getting good barrel life out of it and testing "went really well". I walked over to Proof and they didn't want to acknowledge it...so not sure how far away this is from coming to the public.

When I got back home I tried to find info on this and nothing came up. Then last week the drawing came out. I was really interested when we discussed the capability and performance they were seeing.

Cool, thanks for posting that up. Like others have said, it's not a big leap to knock the shoulder back a couple hundredths on a 6mmAR, but standardization of a capable AR-15 sized round will catch a lot of consumer attention (hopefully Hornady has that squarely in mind).

I wonder what the .gov wanted with the round? Something specialized and small scale no doubt. Either way, it seems like the only reason to establish a SAAMI standard for the round is for commercial introduction. With the standard published, and H headstamped cartridges floating around out there, you'd hope it won't be too long until they are ready to introduce the round.

I like the idea that they were planning on rolling out the round at the NRA Annual Meetings before the Kung Flu killed all that, apparently that's what happened with the Ruger PC Charger.
 

Bantam1

Private
Belligerents
Nov 18, 2008
174
130
49
USA
I'll see if I can get some velocity numbers from him. I am not sure if they are open due to the stupid closures.
 

Ledzep

Chancellor
Belligerents
Jun 9, 2009
2,437
1,512
219
NE
Figure 15-20fps per inch. 18" around 2600-2650fps.

ETA: looks right in line with 6mm AR. Go figure :D
 
  • Like
Reactions: NewsShooter

cleric

Private
Belligerents
Nov 13, 2011
472
133
49
38
Dallas, tx
He said 2750 with the 108 ELDM from a 24" barrel. It will be commercially available in the future. He mentioned it outperforms the 65 Grendel.
as I understand the 6 gt is like 3k fps, so this is only a couple hundred FPS less on an ar frame
 

Bantam1

Private
Belligerents
Nov 18, 2008
174
130
49
USA
I suspect commercial loading might be a little slower, or maybe it can be hand loaded a little hotter. At least there is a ball park number for everyone to think about. It's a barrel change only if you have a 65G build already. Same bolt face.
 
  • Like
Reactions: Earnhardt

Strykervet

Resident Phoenix Eye and Dim Mak Instructor
Belligerents
Jun 5, 2011
4,775
3,314
219
44
Pierce County, WA
Just when I’m close to pulling the trigger on ordering a 12.5” grendel barrel this drops. Now I have to wait and see what support this gets and who wants to be the first to try it out in a short barrel configuration.
Here's mine. It's certainly a bad motherfucker and it's quiet but it looks a lot more high speed than it really is. That 6.5Ultra9 suppressor is just the titties with these 6.5's though.
IMG_0882.JPG

I build a 6.5G SBR and IMO it's not worth it. Maybe before .300BLK came out but not now. I used an 11.5" Lilja bbl. and it's fairly accurate and a very soft shooter but I wouldn't wanna bet my life on it as is and the velocity of a 120gr. Nosler BT is only around 2000-ish. In the 20"bbl. they're quite a bit faster. I think I'll mess with this one and try to find some light FMJ's if they make 'em or just resort to 95gr. pills so at least it'll trump a 5.56 at x range, hopefully to 600 but I haven't mapped it, shot it much or done anything really to work out the bugs yet. Too many forks in the fire.

You can get slightly more velocity out of a .300BLK using supers out of an 8.5"bbl. plus the ability to use subs, which is just a no-go in Grendel. A .300BLK has slightly less velocity than an AK in these shorter bbl.'s but it's shorter, quieter and more accurate so it makes up for it. A 16"bbl. is pretty much on par with the AK.

I seriously doubt a 6mm will perform any better and possibly worse than the Grendel in a short bbl.

Bill A. liked the 22 and 24"bbl.s IIRC. But he also like the 11.5 for a shorty because at the time it was better than 5.56 at that length and like I said, no .300BLK to compete with.

My old neighbor had a 6mm Fat Rat and some other 6mm's, Turbo something comes to mind. Lots of wildcats, he has like fifty rifles and most are wildcats of some sort. Anyway, he said it fired like laser. I still prefer 6.5G.

But have you seen the Army's new cartridge? It's classified but from what folks can tell it pushes a 100something grain 6.8 bullet at 3100fps! NOT 6.8SPC and the bullet weight is heavier, wanna say 120-130gr. but not positive. Chamber pressures for that are estimated to be between 80-90k PSI! That means proof loads gotta be ~100,000PSI! Damn! Now THAT would be the round to go with IF you could get it, but I always figured based on politics that when the army gets a new rifle/ammo, that it'll be unavailable to us plebs. Says round can defeat any and all body armor plus any future armor in the works at range. Including stand alone lvl.4 plates. The General Dynamics rifle they made for it just looks to be the titties, I'd trade half my shit for one if it works as well as it looks.
 

cleric

Private
Belligerents
Nov 13, 2011
472
133
49
38
Dallas, tx
Here's mine. It's certainly a bad motherfucker and it's quiet but it looks a lot more high speed than it really is. That 6.5Ultra9 suppressor is just the titties with these 6.5's though.


I build a 6.5G SBR and IMO it's not worth it. Maybe before .300BLK came out but not now. I used an 11.5" Lilja bbl. and it's fairly accurate and a very soft shooter but I wouldn't wanna bet my life on it as is and the velocity of a 120gr. Nosler BT is only around 2000-ish. In the 20"bbl. they're quite a bit faster. I think I'll mess with this one and try to find some light FMJ's if they make 'em or just resort to 95gr. pills so at least it'll trump a 5.56 at x range, hopefully to 600 but I haven't mapped it, shot it much or done anything really to work out the bugs yet. Too many forks in the fire.

You can get slightly more velocity out of a .300BLK using supers out of an 8.5"bbl. plus the ability to use subs, which is just a no-go in Grendel. A .300BLK has slightly less velocity than an AK in these shorter bbl.'s but it's shorter, quieter and more accurate so it makes up for it. A 16"bbl. is pretty much on par with the AK.

I seriously doubt a 6mm will perform any better and possibly worse than the Grendel in a short bbl.

Bill A. liked the 22 and 24"bbl.s IIRC. But he also like the 11.5 for a shorty because at the time it was better than 5.56 at that length and like I said, no .300BLK to compete with.

My old neighbor had a 6mm Fat Rat and some other 6mm's, Turbo something comes to mind. Lots of wildcats, he has like fifty rifles and most are wildcats of some sort. Anyway, he said it fired like laser. I still prefer 6.5G.

But have you seen the Army's new cartridge? It's classified but from what folks can tell it pushes a 100something grain 6.8 bullet at 3100fps! NOT 6.8SPC and the bullet weight is heavier, wanna say 120-130gr. but not positive. Chamber pressures for that are estimated to be between 80-90k PSI! That means proof loads gotta be ~100,000PSI! Damn! Now THAT would be the round to go with IF you could get it, but I always figured based on politics that when the army gets a new rifle/ammo, that it'll be unavailable to us plebs. Says round can defeat any and all body armor plus any future armor in the works at range. Including stand alone lvl.4 plates. The General Dynamics rifle they made for it just looks to be the titties, I'd trade half my shit for one if it works as well as it looks.
sigs offering is called 277 fury and they released some stats at shot. right now it uses a bi metal casing to support the pressure. If it takes off it could be interesting but I am not sure what level of support it will have
 

Constructor

Private
Belligerents
6mmARC is designed perfectly for today's long-range shooting from an AR platform.

Dimensionally-correct illustration attached shows 6mmARC at COL of 2.260 loaded with a Berger 6mm 105gr Hybrid Target bullet (G1 BC 0.536).
.030 isn't going to make a bit of difference between it and the 6mmAR that has been out since 2006. What will make a difference is any joe blow can walk into a store and buy ammo.
 

BluntForceTrauma

Private
Belligerents
Aug 5, 2014
9
4
6
.030 isn't going to make a bit of difference between it and the 6mmAR that has been out since 2006. What will make a difference is any joe blow can walk into a store and buy ammo.
Agree on both counts. 6mmAR, since they're so similar, is also designed perfectly for a long-range 6mm in an AR.

With its 0.441 case head you get the biggest diameter cartridge that can double stack within a standard AR magazine well, plus you get plenty of room for long, sleek ogives with the boattail optimally seated at the neck/shoulder junction — all within a standard AR mag well.
 
  • Like
Reactions: Earnhardt

Yondering

Sergeant
Belligerents
Mar 16, 2017
574
196
49
Skagit Valley, WA
Figure 15-20fps per inch. 18" around 2600-2650fps.

ETA: looks right in line with 6mm AR. Go figure :D
Yes, all of these 6mm Grendel-based rounds do about the same speeds. The choices right now really come down to who you want to do business with. My 19" 243 LBC is doing ~2760 fps with the 105 BTHP.
 
Last edited:

Yondering

Sergeant
Belligerents
Mar 16, 2017
574
196
49
Skagit Valley, WA
I build a 6.5G SBR and IMO it's not worth it. Maybe before .300BLK came out but not now. I used an 11.5" Lilja bbl. and it's fairly accurate and a very soft shooter but I wouldn't wanna bet my life on it as is and the velocity of a 120gr. Nosler BT is only around 2000-ish. In the 20"bbl. they're quite a bit faster.
LOL, what kind of wimpy loads are you using in that thing? Even the 300 Blackout will do ~2100 fps with a 125gr in that barrel length. My Grendel accuracy load for the 123 ELD is doing 2360 in my 12.5", and that's with good brass life; it can be pushed hotter.

Also, the difference between these short barrels and longer 18-20" barrels is not all that much with the 6.5 Grendel; only about 200-250 fps depending on the barrel.

I'm not sure what you're doing, but it doesn't sound like your experience is a good representation of the Grendel in a short barrel. It absolutely outperforms the Blackout at any distance, but especially past 100 yards or so; that's an apples to oranges comparison. Don't know if you've tried to hit much at 600-700 yards with a short 300 Blackout, but it's not very impressive; in contrast the short Grendel is easy, and in my experience is easier to hit with in the wind than a 16" 5.56 with 75/77gr. At distance, the 6mm versions of the Grendel are another step up for a small frame long range cartridge.
 

Gtscotty

Sergeant of the Hide
Belligerents
Minuteman
Jul 22, 2018
270
226
49
Yes, all of these 6mm Grendel-based rounds do about the same speeds. The choices right now really come down to who you want to do business with. My 19" 243 LBC is doing ~2760 fps with the 105 BTHP.
I want to do business with whoever is offering factory ammo, brass, dies and abundant load data, no one yet, but hopefully Hornady with the ARC soon. The 50 fps or so lower velocity vs some of the wildcat options is an easy trade for me to make for the convenience and time savings in the reloading room.
 

Baron85

Sergeant
Belligerents
Mar 18, 2012
470
112
49
34
What would be cool is if the factory 6mm arc can be shot through some of the different wildcat chambers so people that have already invested can use the factory ammo as needed or hand load to gain the extra performance.
 

Gtscotty

Sergeant of the Hide
Belligerents
Minuteman
Jul 22, 2018
270
226
49
Playing with Quick Load, it looks like compressed RL17 loads should give near top velocities with heavy bullets in the 6mm Grendel variants. That leads me to wonder if 6.5 Staball might be a good heavy bullet powder (with a better packing density), has anyone has any success in the 6mm Grendels with it yet?
 
Last edited:

coach4christ

Head mop pusher
Belligerents
Nov 23, 2010
360
94
34
43
NW Louisiana
I'm very interested in this topic. I looked at the 6mm wildcats really hard but went with the valk instead due to the support factor. Would love to shoot 105-108 pills in the ar 15 package..
 

Constructor

Private
Belligerents
Playing with Quick Load, it looks like compressed RL17 loads should give near top velocities with heavy bullets in the 6mm Grendel variants. That leads me to wonder if 6.5 Staball might be a good heavy bullet powder (with a better packing density), has anyone has any success in the 6mm Grendels with it yet?
I think Re17 is too bulky. I've had better luck with SWM, CFE, N540 and 550, 8208 for lighter bullets.
 
  • Like
Reactions: Gtscotty

MotorOilMcCall

Mandalorian
Hessian
Belligerents
Feb 13, 2014
224
193
49
Buffalo
I just loaded a couple dozen rounds of 6mm Pred.

85gr SGK over 28gr of IMR4895 at 2.150" OAL (worried about a long jump on this one, bullets are pretty short, and to get them seated enough, end up with a long jump to the lands)
100gr Sierra Spitzers (all I could find) over the same load. These I ran at 2.250" OAL

I plan on getting some Vmax or Berger pills to try later, but wanted something to load while I'm stuck home.
 
Last edited:

Ledzep

Chancellor
Belligerents
Jun 9, 2009
2,437
1,512
219
NE
I've been getting 8-10 reloads on my Hornady 6.5 CM brass in a bolt gun.
Hornady brass (barring the occasional factory F-up where the brass actually is made wrong) is fine up to 65,000psi (ETA: In bolt guns, 52-55ksi in the grendel in an AR is a safe limit for the sake of lug loading). Exceed that and you start wrecking primer pockets. Guys like to say "I'm getting ####fps and 'no pressure'". but what they mean is "I'm getting no signs of dangerous excessive pressure", which usually happens around 70-73ksi.

Put another way, loose primer pockets IS a sign of excessive pressure... Lapua, ADG, etc... are harder in the head and handle the higher pressures but that doesn't make it a good idea (barrel life, brass life, safety factor, etc..).
 
Last edited:

Constructor

Private
Belligerents
Hornady brass (barring the occasional factory F-up where the brass actually is made wrong) is fine up to 65,000psi. Exceed that and you start wrecking primer pockets. Guys like to say "I'm getting ####fps and 'no pressure'". but what they mean is "I'm getting no signs of dangerous excessive pressure", which usually happens around 70-73ksi.

Put another way, loose primer pockets IS a sign of excessive pressure... Lapua, ADG, etc... are harder in the head and handle the higher pressures but that doesn't make it a good idea (barrel life, brass life, safety factor, etc..).
Sorry buddy I don't think you can load anywhere near 65000 psi. I have pressure equipt and anything past 58000 starts bulging the cases...damn near rupturing. Norma brass will outlast all others.
This is what the belted Grendel magnum looks like and it happens when you push the pressure.
grendel belted.jpg
 
  • Wow
Reactions: MotorOilMcCall

cleric

Private
Belligerents
Nov 13, 2011
472
133
49
38
Dallas, tx
Playing with Quick Load, it looks like compressed RL17 loads should give near top velocities with heavy bullets in the 6mm Grendel variants. That leads me to wonder if 6.5 Staball might be a good heavy bullet powder (with a better packing density), has anyone has any success in the 6mm Grendels with it yet?
what other powders were on the list? I think cfe 223 and leveroution are popular with grendel reloaders
 
  • Like
Reactions: Lightning8

BluntForceTrauma

Private
Belligerents
Aug 5, 2014
9
4
6
SAAMI drawing for 6mmARC says Maximum Average Pressure (MAP) is 52,000 psi and is still launching a 108gr @ 2700 fps. This cartridge is gonna be just fine on pressure and will be a joy to shoot with easy recoil.

Want to hotrod it with handloads? Cool. Your choice. Practice standard safe-reloading practices. I suggest one stops adding pressure before one gets a belted magnum effect on one's brass.
 
  • Like
Reactions: lumberjack78

Gtscotty

Sergeant of the Hide
Belligerents
Minuteman
Jul 22, 2018
270
226
49
AR-Comp and H4895 work well in the Grendel, seems like they'd be good temp insensitive powders to try in the ARC as well.
 

Yondering

Sergeant
Belligerents
Mar 16, 2017
574
196
49
Skagit Valley, WA
SAAMI drawing for 6mmARC says Maximum Average Pressure (MAP) is 52,000 psi and is still launching a 108gr @ 2700 fps. This cartridge is gonna be just fine on pressure and will be a joy to shoot with easy recoil.

Want to hotrod it with handloads? Cool. Your choice. Practice standard safe-reloading practices. I suggest one stops adding pressure before one gets a belted magnum effect on one's brass.
Exactly. All the constant harping about how the 6.8 handles more pressure is pretty pointless. The fat Grendel case does what it does, and gets it done at lower pressure and we're all fine with that. That harping also disregards the huge quantities of garbage 6.8 brass out there that doesn't handle the 6.8's supposed pressure advantage. The fanboy 6.8 vs Grendel arguments get really old; just shoot/buy what you want and enjoy it, and let other people enjoy theirs.

I suspect this 6mm ARC is .030" shorter specifically so that it won't be fired in wildcat chambers. There's not much reason to push the shoulder back otherwise; it didn't need the extra magazine space.

Also - Leverevolution is where it's at for the 6mm Grendel cartridges with medium-heavy bullets. You can expect both top accuracy and velocity.
 
  • Like
Reactions: SupressYourself

BluntForceTrauma

Private
Belligerents
Aug 5, 2014
9
4
6
If they didn't shorten the case to avoid accidental loadings and their attendant legal issues, then they shortened the case for technical reasons to "build-in" accuracy.

Many seem to think that technical accuracy is improved when bullets are seated with the boattail at the neck/shoulder junction. I don't know who, if anyone, has rigorous technical proof. Hornady has designed the 65CM, 65PRC, and 300PRC with this feature, so they certainly believe it, and they've also done so with the 6mmARC.

If I was designing a 6mm Grendel, I'd have set the case length at 1.550 as a nod to more powder and shorter bullets. Yes, long bullets would be stuck farther into the powder column, but if one assumes there's no detriment to accuracy, then it's a fair compromise. If there IS a provable accuracy advantage to Hornady's theory, then I agree with the 6mmARC case length as designed at 1.490.
 

Attachments