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Hornady 6mm ARC.
- Thread starter orkan
- Start date
Kind of neat to see what's essentially a SAAMI-spec 6 Grendel come on the scene, even though I have no intention of dropping my 6RAT rifles to try the ARC. Started out with a 28" bbl'd AR15 6RAT match rifle; sold it after switching to an Eliseo R5 in 6BR as my XC HP rifle. But still had a soft spot for the RAT, so bought a CZ527 carbine in 7.62x39, then turned the shank of a Krieger #4 sporter down to be a better fit for the little 527, chambered it with my 6RAT reamer, finished at 24", and swapped a Rifle Basix trigger for the OEM single set one, and enjoy! Then decided to build an AR around a Krieger 24" bbl, and most recently - after Howa finally got some Mini bbl'd actions out in 6.5 Grendel & 7.62x39, I built myself another 6RAT on a Mini with a 24" Bartlein in light Palma contour. I get a little over 2800fps with S95MKs out of either the Howa or CZ, but prefer the Howa for its push-feed action, which feeds more smoothly & with better reliability than the CZ. Not really pushing any of these rifles hard for velocity, accuracy is more attractive & important to me. Only downside I see with the the RAT is the need for fireforming - so for guys who hate doing that, the 6 ARC might be a good alternative. I've used LMT & J-P enhanced SAE 9310 bolts in both my ARs, and in every RAT bbl I've done for a customer. Even though my RAT loads generally aren't max pressure barn-burners, I'll stick with these enhanced 9310 bolts for any round based on the Grendel boltface.
'Fraid not. The velocity I'm getting with factory ammo (52ksi) is right in line with the published data/charts. 2700-2750 at the muzzle doing 2820-2850 with 4" more barrel is nothing exciting.
A clear distinction needs to be made with this caliber as to "bolt gun" 62ksi loads and "Gas gun" 52ksi loads. Current published load data is only at 52ksi max for the sake of AR-15s' bolts.
You'll see a few powders make 2825-2875, maybe even edge in on 2900fps with the 105-110gr bullets in 24" barrels when 60-62ksi data is published. Figure 20fps per inch and all of a sudden a 28" barrel pushing 2940 doesn't seem so crazy... Because it's not.
I look forward to some factory bolt guns. Any word on first productions and ETA on when someone like Ruger/Howa/or Bergara will start offering them?
Gun makers who are producing the 6mm ARC
Adams Arms
APF Armory
Barrett
Brownells
Christensen
CMC Triggers
CMMG
GAP
Geissele
Howa
Lantac
Mile High Shooting Accessories
Mossberg
NEMO
Noveske
Odin Works
Proof
Radical Firearms
SanTan Tactical
Seekins Precision
Uintah Precision
Wilson Combat
Thanks for that, wonder when the Howa mini will actually be chambered and offered up. I'll keep my eyes peeled.
I like A2520 in 6.5G, it is slower than Tac and CFE223 but more compact. 30.6gr still isn't compacted. 6 Grendel has been around a long time and I think the speed claims above are going to turn out to be simple over pressure.
I agree with your assessment of velocity claims. I've owned four 6RAT rifles, the longest bbl being a 28" Bartlein 1:7.8tw on an AR15 match rifle, the following three all having 24" bbls (another Bartlein & two Kriegers), and looking back at a lot of chronograph data over the years, I never got close to some of the velocity claims I've seen in this thread - and the RAT has more case capacity than the ARC. Obviously, since I still have three of these rifles, and shoot them with some regularity, I like 'em just fine, and have no problem accepting what I get out of this little case. If I want more velocity, there are three Dashers in the safe, along with three 6x47s and a couple of 6XCs.
I could hardly wait for Howa to get bbl'd actions in 6.5 Grendel out so I could re-barrel one for the RAT, and since we now have a couple of sources of aluminum DBM to replace the chintzy OEM plastic unit, as well as a couple of nicely done BDL-style hinged floorplate units that get away from having to use the rather poor plastic 5-rd mags, the Howa has come into its own as far as being a quality rifle. If only someone would come out with better magazines that would fit & work with the aluminum DBMs, in my mind, the Howa Mini would be the top choice for shooters wanting an action to use with all the 6mm versions of the 6.5 Grendel - unless Sako L461 Vixens were still available at prices comparable to the Howa.... To confirm how much I enjoy the small actions - from top to bottom: CZ527 6RAT, Sako 6PPC, Sako 223, Howa 6.5 Grendel/Bartlein in B&C stock, Howa 6RAT/Bartlein in McM Game Scout.
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In AR-15s. In AR-15's Hornady has already published 52ksi data and my brief experience with my own AR-15 in 6 ARC (1 range trip) is that "pressure signs" show up much earlier than in a bolt gun. Not hard to get ejector swipes. HOWEVER... there is a gas system in play, and gas timing to contend with, and powder burn rate that would produce the highest velocities probably also has the highest port pressures (right? because velocity is correlated to the area under the pressure vs. time curve, more area means the curve is higher longer down the barrel if the peak is fixed at a ceiling), which in turn means the gas system is going to start trying to unlock the breech at a higher retained pressure inside the case (even if the bullet is out of the barrel by the time unlocking starts, the pressure takes time, as small of a time as it is, to subside), which means stuff like ejector swipes are going to show up much sooner in an AR-15 than they would in a bolt gun. Material on the case head may still be ELASTICALLY (could be as low as 20-40ksi) pushed into the ejector hole when the bolt starts to unlock, shaving some of it away, where as in a bolt gun you have to PLASTICALLY flow material (70ksi or more) before you see ejector swipes. Some of it can be tuned out with adjustable gas systems, weights, etc...
Nonetheless, In a bolt gun the pressure peaks, subsides, then waits a quarter second before the quickest bolt runner opens the bolt. If anyone has tried reloading for a gas gun in .308, 6.5 creed, etc.. You've seen the same thing. A load (even factory ammo) that is fine in a bolt gun will shave brass all over in an auto-loader. It's not peak pressure, it's residual pressure at the time the bolt unlocks. A fun test might be to remove the gas block completely (and handguard if it's going to get flame-jetted) and take a load that is ejector swiping normally and see if it still does it when you operate the rifle as a bolt-action.
After a cursory glance at a few forums Google provided, I still think my numbers are in line. I think a lot of folks are pushing their luck in AR-15s with 6AR/Turbo/RAT/LBC... lol Nonetheless, the powder charge vs. velocity vs. barrel length all correlate. Hopefully official 60-62ksi data will get published soon.
Another variable is brass and internal capacity. Especially with as small a case as this one it doesn't take much to change internal volume by a significant percentage, and that can really skew pressure and velocity numbers. I should also mention that lot-to-lot consistency on powder can change things considerably.
As far as your 6.5 Grendel w/100gr pills. Take 20-25fps per inch and add 8" of barrel to that. Right off the bat you're 2890-2930. Try a few powders with burn rates faster/slower and maybe one has the right density to fit enough in the case to get you to 2950 in a 28" pipe. Barrel length is always the safest method to get more speed.
Nonetheless, In a bolt gun the pressure peaks, subsides, then waits a quarter second before the quickest bolt runner opens the bolt. If anyone has tried reloading for a gas gun in .308, 6.5 creed, etc.. You've seen the same thing. A load (even factory ammo) that is fine in a bolt gun will shave brass all over in an auto-loader. It's not peak pressure, it's residual pressure at the time the bolt unlocks. A fun test might be to remove the gas block completely (and handguard if it's going to get flame-jetted) and take a load that is ejector swiping normally and see if it still does it when you operate the rifle as a bolt-action.
After a cursory glance at a few forums Google provided, I still think my numbers are in line. I think a lot of folks are pushing their luck in AR-15s with 6AR/Turbo/RAT/LBC... lol Nonetheless, the powder charge vs. velocity vs. barrel length all correlate. Hopefully official 60-62ksi data will get published soon.
Another variable is brass and internal capacity. Especially with as small a case as this one it doesn't take much to change internal volume by a significant percentage, and that can really skew pressure and velocity numbers. I should also mention that lot-to-lot consistency on powder can change things considerably.
As far as your 6.5 Grendel w/100gr pills. Take 20-25fps per inch and add 8" of barrel to that. Right off the bat you're 2890-2930. Try a few powders with burn rates faster/slower and maybe one has the right density to fit enough in the case to get you to 2950 in a 28" pipe. Barrel length is always the safest method to get more speed.
18" - 2600 (my 18" AR is 2596 avg)
28"- 2835 (my 28" bolt gun, same ammo, 52ksi)
23fps per inch
Correlates to this chart... like exactly.
I'm about to stop posting about this. If you don't want to believe it, that's cool man. Wait a few months to believe it then.
Again, there's a hole in the powder lineup for this volume of case @ 6mm bore as far as extruded powders go. Guys are running extruded powders in the Dashers/BR/BRA/BRX/BRXYZLMNOP, which is fine. If you run Varget, 8208, h4895, RL-15, etc.. in the 6 ARC you will also be slow. Subtract 150-200fps from the above.
PLEASE NOTE THIS IS 52,000psi DATA FOR AN 18" BARREL BEFORE YOU TELL ME HOW SLOOWWWW IT IS.
There just happens to be a window of available spherical powders that jive with this case capacity and bullet weight really well.
28"- 2835 (my 28" bolt gun, same ammo, 52ksi)
23fps per inch
Correlates to this chart... like exactly.
I'm about to stop posting about this. If you don't want to believe it, that's cool man. Wait a few months to believe it then.
Again, there's a hole in the powder lineup for this volume of case @ 6mm bore as far as extruded powders go. Guys are running extruded powders in the Dashers/BR/BRA/BRX/BRXYZLMNOP, which is fine. If you run Varget, 8208, h4895, RL-15, etc.. in the 6 ARC you will also be slow. Subtract 150-200fps from the above.
PLEASE NOTE THIS IS 52,000psi DATA FOR AN 18" BARREL BEFORE YOU TELL ME HOW SLOOWWWW IT IS.
There just happens to be a window of available spherical powders that jive with this case capacity and bullet weight really well.
Thanks for taking the time to share the data and your experiences. Until others start loading for their own 6ARC barrels and seeing much slower velocities then I just don’t see the reason to call yours an outlier.
I think the most outlying factors are that you are running a 28” barrel in a bolt gun—which more than explains everything I need to know for now.
I have 3 guns bolt guns in the Grendel family
Stiller 223 action(sako extractor)
2 -Tikka T3 223 actions
All three where opened up and run without any issues whatsoever
I've done Grendel load development for almost every powder on that list plus some that aren't. To get 2945 with 110A-Tip out of a 28" barrel you would have to be north of 62K PSI. Both my own personal experience, that of others in this thread, and QL have your stated performance well above what anyone considers a safe load. The question you should be asking yourself is why everyone else who's loaded 6AR (which has more case capacity than 6ARC) hasn't been seeing the velocity you're seeing now? Your chronograph is telling you that you're over max but you aren't listening.
Frankly, 6ARC out of an AR makes tons of sense. However, 6ARC out of a full sized bolt action makes zero sense if your objective is to push it to 6BRA or Dasher performance. You can get the same exact performance from a 6GT without the non standard bolt face, feeding problems/custom magazines, or sky high pressure. All of them will have the same recoil using the same bullet and velocity.
@reubenski Look into AA2520, BLC-2, and CFE223 for your Grendel. Not guaranteeing anything, I've not loaded 100gr class pills in the Grendel but judging by burn speeds and velocities from Hodgdon, Accurate, and Hornady those look promising. 2520 especially. You're going to want a little bit faster burn rate than what works in the ARC, having the larger bore diameter on the Grendel.
Great discussion guys, appreciate it a lot. Thanks for keeping the discussion focused and not an insult competition.
I will add W748 to your powder list as well. Another ball powder that produces lots of velocity in the 6.5G. 2520, BLC2 and 748 all produced great precision in my 6.5G gasser, with lots of velocity w. the 100gr range of 6.5mm bullets. I was using the 107gr SMK and it would print v nice groups. It was easy to see why the benchrest guys use the PPC cartridge - precision was stupid easy to achieve.
I'm now looking forward to messing around with the 6ARC, going to try either the 88gr Flatline or the new 95gr Flatline. Hoping for stupid easy precision, low SD/ESs at 2900+fps MV from 20" gasser that weighs in under 12lbs. Ground hogs and yotes on my farm are on notice!
recent guns & ammo magazine says the US military is skipping 6.5CM and converting from 7.62x51mm to 6mm ARC because of the smaller cartridge and lighter load outs and longer barrel life. don't know anything concrete...
I'm surprised by the numbers you are getting too considering that is out performing other rounds with more case capacity. But it isn't impossible that you got a barrel that just shoots fast.
As more people go a similar direction as you, there will be more data to comb over. That's the biggest benefit of a community like this is the sharing of information. If that's what you are getting, that's what your getting. Just the results may vary for others.
I have friends over at Savage who are telling me that yes, we will get one, no timetable.
I have received a flat "NO!" for the time being from Ruger, citing their desire to cash in on the very busy AR market right now. They understood that it would be easy to run another barrel and reamer setup for their existing 6.5G guns, but they were not interested for now.
Howa hasn't said a peep and I haven't found any information anywhere about a release date.
I brought up the question of a Howa Mini in 6ARC being offered with my sales rep at Legacy Sports today after placing an order for a couple of Mini rifles, and was told that they're working on it. No timeline, and it's no surprise since they already do the 6.5 Grendel & 7.62x39, both of which have the same boltface as the ARC. Why on earth would they miss out on the opportunity to sell a bunch of these little rifles as they ride the wave of popularity of the ARC?
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@Cascade Hemi , @reubenski
Lucky coincidence, but take my 23fps/inch and figure what a 28" barrel would do... Then scroll up to the first post on page 3...
Lucky coincidence, but take my 23fps/inch and figure what a 28" barrel would do... Then scroll up to the first post on page 3...
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This one bit me hard. I jumped in with both feet and could not be happier.
I had ES Tactical build me a conversion kit for my MDR, and it has been a blast. Real easy to load the 105’s and shoots lights out.
Shot this at 100 yds with my handloads, but the Hornady stuff shot just as good.
I had ES Tactical build me a conversion kit for my MDR, and it has been a blast. Real easy to load the 105’s and shoots lights out.
Shot this at 100 yds with my handloads, but the Hornady stuff shot just as good.
Not sure if brought up. Anyone know what the status on brass is? Seems to be a rare commodity rn. Hope they are ramping up production soon.
I don't doubt you're getting those velocities and I'm glad you're doing the load work. Please let us know what kind of brass longevity you get. I'd guess you're in the 63k PSI range.
When I get a chance I'll reload at the range and kill a case. I've got 4 firings on a few cases and they're still tight in the primer pocket. I just mixed all of my fired stuff together yesterday so I'll start fresh with a new round once.
6mm ARC = 6mm Grendel in my eyes.
Pretty much good idea for the AR but the magazine reliability issues kill it for me.
in a bolt gun it doesn’t make much sense either unless I want to run a Howa 1500 Micro Action.
it seems like a cool new hype cartridge that does nothing for my real world needs.
Pretty much good idea for the AR but the magazine reliability issues kill it for me.
in a bolt gun it doesn’t make much sense either unless I want to run a Howa 1500 Micro Action.
it seems like a cool new hype cartridge that does nothing for my real world needs.
It looks like Savage has a pair of 6mm ARC bolt guns that can be found on some different sites (out of stock but listed), although I don't see them on the Savage website.
I wouldn't hold you breath on this one. I called Savage the other day to see if they are still producing the 110 prairie in 224 Valkyrie and they said that it was discontinued (it was in production for almost a year) and because of current state of EVERYTHING that they are only working on rifles that will guaranty sales... aka AR15 and the more popular hunting rounds.
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