MRGG-A (6.5 CM) vs 6 ARC?

rlsmith1 · Jan 8, 2025

Of course Hornady has done a lot of good with the 6 ARC and I love my 14.5" version has been great. Now I'm starting to see (or maybe just pay attention to) 14.5" 6.5 Creed rifles and I'm kind of intrigued. Anyone have experience with both and have any input?

I love my 18" 6.5 CM AR10 and I'm trying not to convince myself to chop it to 14.5" but the 14.5" AR10's seem pretty sweet and my MK5 2-10 sure feels more at home on an AR10 than an AR15

Bigjake83 · Jan 8, 2025

rlsmith1 said:
Of course Hornady has done a lot of good with the 6 ARC and I love my 14.5" version has been great. Now I'm starting to see (or maybe just pay attention to) 14.5" 6.5 Creed rifles and I'm kind of intrigued. Anyone have experience with both and have any input?

I love my 18" 6.5 CM AR10 and I'm trying not to convince myself to chop it to 14.5" but the 14.5" AR10's seem pretty sweet and my MK5 2-10 sure feels more at home on an AR10 than an AR15

A buddy of mine bought this rifle from PSA. I helped him set everything up and it was easily a Sub MOA rifle with Hornady American Gunner 140gr ammo, keep in mind that was right out of the gate with no break-in so I'm sure once the barrel brakes in and with handloads it could realistically hit the half MOA mark.

They're out of stock now so I would just check in with PSA every week, PSA seems to do a good job at restocking thier rifles in a timely manner.

rlsmith1 · Jan 8, 2025

Bigjake83 said:
A buddy of mine bought this rifle from PSA. I helped him set everything up and it was easily a Sub MOA rifle with Hornady American Gunner 140gr ammo, keep in mind that was right out of the gate with no break-in so I'm sure once the barrel brakes in and with handloads it could realistically hit the half MOA mark.

They're out of stock now so I would just check in with PSA every week, PSA seems to do a good job at restocking thier rifles in a timely manner.

View attachment 8586791

Did you get a chance to shoot it much past 500y yet? Seems like Norma 130 Golden Match might be a good bullet for that barrel length too?

ut755ln · Jan 8, 2025

rlsmith1 said:
Of course Hornady has done a lot of good with the 6 ARC and I love my 14.5" version has been great. Now I'm starting to see (or maybe just pay attention to) 14.5" 6.5 Creed rifles and I'm kind of intrigued. Anyone have experience with both and have any input?

I love my 18" 6.5 CM AR10 and I'm trying not to convince myself to chop it to 14.5" but the 14.5" AR10's seem pretty sweet and my MK5 2-10 sure feels more at home on an AR10 than an AR15

To me they are completely different animals. The advantage of the 6 ARC is that you take a small frame standardized AR and increase the capability versus 5.56. Most of the 6 ARC rifles I have shot or seen shot have no problem staying super sonic to 1k yards and shoot flatter at any range in between versus 5.56.

The 6.5 CM gas guns are large frame, not small frame. So to me they are heavier, kick more, less standardized, ect. They can be just as accurate and depending on the setup (barrel length, cartridge) definitely have more range than the 6 ARC. The MRGG entries the military conducted were very similar in terms of goal compared to the 6 ARC. They are taking an existing platform like the KAC SR25 and changing to a more efficient cartridge that extends the range and arguably the lethality of the weapon.

rlsmith1 · Jan 8, 2025

ut755ln said:
To me they are completely different animals. The advantage of the 6 ARC is that you take a small frame standardized AR and increase the capability versus 5.56. Most of the 6 ARC rifles I have shot or seen shot have no problem staying super sonic to 1k yards and shoot flatter at any range in between versus 5.56.

The 6.5 CM gas guns are large frame, not small frame. So to me they are heavier, kick more, less standardized, ect. They can be just as accurate and depending on the setup (barrel length, cartridge) definitely have more range than the 6 ARC. The MRGG entries the military conducted were very similar in terms of goal compared to the 6 ARC. They are taking an existing platform like the KAC SR25 and changing to a more efficient cartridge that extends the range and arguably the lethality of the weapon.

Yeah I agree, but in some ways the 6.5 CM variant is a little more standardized (standard AR10 bolt and magazines) when compared to the ARC (Grendel bolts and mags). I do think the ARC / Grendel cartridge is going to stick around, but being able to run Creed ammo is a really nice feature.

Might just have to try it but I'm a little hesitant to chop this Criterion that shoots so well as an 18" right now!

rlsmith1 · Jan 8, 2025

After running the numbers, the 6 ARC shooting a 108 ELD should expand out to 680y (2525fps MV, 1600fps threshold) while the 6.5 CM shooting a 140 ELD should expand out to 710y (2450fps MV, 1600fps threshold) which is pretty much a wash. Of course the Creed has more energy, but both have over 550ft/lbs of energy at 750y (the 6.5 has 700ft/lbs while the 6 has 575ft/lbs). They are also within 0.5 MIL for drop and 0.1 MIL for wind out to 750y and stay supersonic to pretty much the same distance (within 60y of each other).

Not sure it's worth the weight penalty to me but may try it down the road if real world results are different. Below is a summary of assumptions which are best I could find online (6 ARC is pretty much where I've seen things in my rifle).

14.5" 6 ARC
108 ELD M @ 2525fps
1000' std DA

14.5" 6.5 Creed
140 ELD M @ 2450fps
1000' std DA

smcfarland · Jan 10, 2025

I would look at how far you realistically want to shoot, and the cost of ammo for each. If under 600m and any kind of hunting application I would go with the 6.5cm shooting Hornady 100 ELD-VTs at under $1.50/rd for anything smaller than elk for best likely terminal performance. If shooting longer range on steel/targets looks like a wash and I’d go with cheapest/available ammo.

rlsmith1 · Jan 10, 2025

smcfarland said:
I would look at how far you realistically want to shoot, and the cost of ammo for each. If under 600m and any kind of hunting application I would go with the 6.5cm shooting Hornady 100 ELD-VTs at under $1.50/rd for anything smaller than elk for best likely terminal performance. If shooting longer range on steel/targets looks like a wash and I’d go with cheapest/available ammo.

Kinda wild it’s a logical answer to use the large frame for close stuff and small frame for further away. Goes to show how much Hornady did their homework in my opinion.

A 25 cal with appropriate bullets would be legit in a large frame and be the best of both worlds. 6.5 heavies are just a little long

putput30 · Jan 10, 2025

rlsmith1 said:
Kinda wild it’s a logical answer to use the large frame for close stuff and small frame for further away. Goes to show how much Hornady did their homework in my opinion.

A 25 cal with appropriate bullets would be legit in a large frame and be the best of both worlds. 6.5 heavies are just a little long

I’m kinda torn between the two tbh. They both have their pros and cons. I’m slightly leaning towards an Mrgg-a type rifle if the weight isn’t to high. I’m hoping Geissele releases theres sometime soon. Either way it’s a good problem to have when he got so many options.

AustinP69 · Jan 20, 2025

I totally don't understand why break new ground on this intermediate length receiver AR (other than to drum up new sales) when platforms like the SR-25/Large frame AR in 6.5 Creed already have paid the price for developing reliability

MaximusDecimusMeidius · Jan 20, 2025

rlsmith1 said:
After running the numbers, the 6 ARC shooting a 108 ELD should expand out to 680y (2525fps MV, 1600fps threshold) while the 6.5 CM shooting a 140 ELD should expand out to 710y (2450fps MV, 1600fps threshold) which is pretty much a wash. Of course the Creed has more energy, but both have over 550ft/lbs of energy at 750y (the 6.5 has 700ft/lbs while the 6 has 575ft/lbs). They are also within 0.5 MIL for drop and 0.1 MIL for wind out to 750y and stay supersonic to pretty much the same distance (within 60y of each other).

Not sure it's worth the weight penalty to me but may try it down the road if real world results are different. Below is a summary of assumptions which are best I could find online (6 ARC is pretty much where I've seen things in my rifle).

14.5" 6 ARC
108 ELD M @ 2525fps
1000' std DA

14.5" 6.5 Creed
140 ELD M @ 2450fps
1000' std DA

if you can get 2500 fps out of a 115 DTAC then the bc's and velocities would be very close

LRRPF52 · Jan 20, 2025

AustinP69 said:
I totally don't understand why break new ground on this intermediate length receiver AR (other than to drum up new sales) when platforms like the SR-25/Large frame AR in 6.5 Creed already have paid the price for developing reliability

When the DoD entities that were working with Hornady ran through a series of scenario-based evaluations using 12” to 18” 6.5 Grendels from close-in out to long range, after the evals, they were asked:

“Which stages of fire would you have preferred to have an SR-25/large frame gasser instead, or were there any?"

Without exception, every shooter said, “No, I can’t think of one now that you mention it."

Hornady then said they could tweak the cartridge a little and deliver something for them.

That’s where 6mm ARC came from.

I’m also a big fan of AR-10s and SR-25s, but I don’t like all the penalties that come with them.

Weight, bulk, recoil-induced loss of sight picture (difficulty self-spotting), reduced magazine capacity, ammo weight, loss of mobility/maneuverability, component wear.

This is why the High Performance Intermediate Rifle cartridges in small frames make a lot of sense.

Tex68w · Jan 21, 2025

LRRPF52 said:
When the DoD entities that were working with Hornady ran through a series of scenario-based evaluations using 12” to 18” 6.5 Grendels from close-in out to long range, after the evals, they were asked:

“Which stages of fire would you have preferred to have an SR-25/large frame gasser instead, or were there any?"

Without exception, every shooter said, “No, I can’t think of one now that you mention it."

Hornady then said they could tweak the cartridge a little and deliver something for them.

That’s where 6mm ARC came from.

I’m also a big fan of AR-10s and SR-25s, but I don’t like all the penalties that come with them.

Weight, bulk, recoil-induced loss of sight picture (difficulty self-spotting), reduced magazine capacity, ammo weight, loss of mobility/maneuverability, component wear.

This is why the High Performance Intermediate Rifle cartridges in small frames make a lot of sense.

This ^^^^

The 6 ARC gives me everything I want from a large frame gasser inside of 800 and all while staying in a small frame with less weight and recoil. I too like the idea of a 6.5 shorty gasser and I might add one in the coming years (LMT, KAC or Geissele) but it's not high on the priority list since there's so much overlap and if I am going to add weight and length to the scenario I'll just opt to shoot 6.5 out of my bolt gun.

steve123 · Jan 21, 2025

Tex68w said:
This ^^^^

The 6 ARC gives me everything I want from a large frame gasser inside of 800 and all while staying in a small frame with less weight and recoil. I too like the idea of a 6.5 shorty gasser and I might add one in the coming years (LMT, KAC or Geissele) but it's not high on the priority list since there's so much overlap and if I am going to add weight and length to the scenario I'll just opt to shoot 6.5 out of my bolt gun.

I sold my 243 and 308 large frames years ago after buying a 6MMART40. Man that was one precise and soft shooting AR. So much so I won a long range steel night match with it once while using the only semi.
It had a 26" barrel sending 105Amax at 2900. A hot load but that's where it shot the best.

Jsp556 · Jan 22, 2025

You didn’t say if this was going to be used as a target only, varmint/predator rig, medium game, do it all rifle or what.

Personally, I’d leave a good shooting rifle alone and build or buy what I wanted next.

The ICAR type rifles coming out may allow for some higher performance from the 6 arc so it may be worth waiting if that interests you.

As much as I like my large frame guns I find myself shooting my 18” Grendel and 16” 6 ARC guns more and more while those large frames sit in a safe.

steve123 · Jan 23, 2025

How much extra velocity are people getting with bullets seated out farther, with a tad more powder, when using 105-ishgr, in 6 ARC?

rlsmith1 · Jan 23, 2025

steve123 said:
How much extra velocity are people getting with bullets seated out farther, with a tad more powder, when using 105-ishgr, in 6 ARC?

Check out the 6 ARC gas gun vs bolt gun data, I think it's 150 fps or so

DeathBeforeDismount · Jan 26, 2025

The same difference you get out of any Gas vs bolt gun. One can handle much higher pressures (and hide pressure signs, which can be a saftey risk in itself) than the other. 6 arc, 6.5 creed ect. Mag length also comes into play as the small frame ar severely limits COAL. The large frame does as well but not as restrictive considering the uber efficient cartridges we would use.

rlsmith1 · Thursday at 12:22 AM

This that have a rifle length 14.5” 6.5 CM, what is your gas port size and what are you running for a buffer?

MK20 · Thursday at 2:36 AM

I have been saying for years that an intermediate size rifle frame was needed between ar 15 and ar 10.

45-90 · Thursday at 5:31 AM

MaximusDecimusMeidius said:
if you can get 2500 fps out of a 115 DTAC then the bc's and velocities would be very close

I ran the 115 DTAC in 6 ARC to 2603 fps in an 18" Proof barrel, but 2532 fps is where it was running good. So it would depend on the barrel 14.5" would be really pushing it at 2500 fps...
My go to load is 108 gr eldm at 2667 fps Ave fps its very accurate in this barrel.
The 112, 110, and 115 grain all shoot over 2550 fps in the 18" barrel.

Cascade Hemi · Thursday at 10:27 AM

45-90 said:
I ran the 115 DTAC in 6 ARC to 2603 fps in an 18" Proof barrel, but 2532 fps is where it was running good. So it would depend on the barrel 14.5" would be really pushing it at 2500 fps...
My go to load is 108 gr eldm at 2667 fps Ave fps its very accurate in this barrel.
The 112, 110, and 115 grain all shoot over 2550 fps in the 18" barrel.

That's a great velocity so long as you don't mind running 65kPSI in an AR15 Grendel/ARC. Maybe bolt technology has come far enough to disregard the relatively low Grendel pressure ceiling though.

45-90 · Thursday at 12:33 PM

Cascade Hemi said:
That's a great velocity so long as you don't mind running 65kPSI in an AR15 Grendel/ARC. Maybe bolt technology has come far enough to disregard the relatively low Grendel pressure ceiling though.

Hornady’s load data for an 18" gas gun is 2575 fps for the 110 Atip .604 g1 BC
Run the 115 DTAC .620 BC at the same speed or the .634 BC 115 gr RDF...or the 112 gr Barnes....I shot them all in that velocity area with the 18" AR 15.
The 2603 fps 6 DTAC was .2 gr over book max but seated to 2.290" use in fire formed Grendel basic or reformed Grendel cases, it works...and ya "might" get 2500 fps out of your 14.5" barrel.

LRRPF52 · Thursday at 12:44 PM

MK20 said:
I have been saying for years that an intermediate size rifle frame was needed between ar 15 and ar 10.

Army Ordnance Board had Stoner and the drafters at ArmaLite in Hollywood chasing their tails with more intermediate cartridge designs, while they tried to push the M14 across the finish line into mass-production through the old arsenal system.

Their efforts may have been genuine or nefarious, but I think that was the direction the AR-15 should have evolved more in the beginning, not being limited to the .222 Remington case head size cartridges like it was.

One of the intermediate cartridges they were using was the 25 Remington necked down to .224”.

I think the whole limiting parameters to .224” was handicapping them from achieving the down-range performance they were looking for, as it could have been done much better with 6mm, .257”, or 6.5mm with a slightly-larger case.

A slightly-larger mag well and magazine would have kept the rifle still very lightweight and compact, without being a beast like the AR-10. I still think 5.56 has been a great SCHV solution, up until you start looking at some common barriers and distance where battle rifle cartridges rule the roost, but have all their weight/recoil/bulk/limited round count limits nobody wants.

Cascade Hemi · Thursday at 1:04 PM

45-90 said:
Hornady’s load data for an 18" gas gun is 2575 fps for the 110 Atip .604 g1 BC
Run the 115 DTAC .620 BC at the same speed or the .634 BC 115 gr RDF...or the 112 gr Barnes....I shot them all in that velocity area with the 18" AR 15.
The 2603 fps 6 DTAC was .2 gr over book max but seated to 2.290" use in fire formed Grendel basic or reformed Grendel cases, it works...and ya "might" get 2500 fps out of your 14.5" barrel.

Hornady's load data only applies to their test barrel. Velocity is the pressure sign for Grendel. I rounded down the predicted pressure by 5kPSI. 115DTAC at 2.290 going 2603fps out of an 18" barrel is actually predicted to have greater than 70kPSI pressure. Again, maybe bolt technology has improved to the point it doesn't matter any longer.

LRRPF52 · Thursday at 1:29 PM

Cascade Hemi said:
Hornady's load data only applies to their test barrel. Velocity is the pressure sign for Grendel. I rounded down the predicted pressure by 5kPSI. 115DTAC at 2.290 going 2603fps out of an 18" barrel is actually predicted to have greater than 70kPSI pressure. Again, maybe bolt technology has improved to the point it doesn't matter any longer.

If you’re using QL or GRT, we found that the calculated pressures were 9,000 to 14,000psi higher than real-world pressure trace and industry-tested data in test breeches at Hodgdon’s with 6.5 Grendel.

I take any numbers I see from those programs with a grain of salt.

Cascade Hemi · Thursday at 2:24 PM

LRRPF52 said:
If you’re using QL or GRT, we found that the calculated pressures were 9,000 to 14,000psi higher than real-world pressure trace and industry-tested data in test breeches at Hodgdon’s with 6.5 Grendel.

I take any numbers I see from those programs with a grain of salt.

How long ago?

Hornady's load data conflicts with Sierra and Hodgdon, both of which match QL and user reported data on this site. Recent, and historical, reported data on Grendel forum also matches current QL. My own load data closely matches QL. Five years ago QL was really off for Grendel, after quite a few updates it is pretty spot on.

45-90 · Thursday at 9:34 PM

Here's the manual 110 gr Atip at 2575 fps in 18" AR gas gun Noveske Model N4 starting on page 239 of the Hornady manual. Not a test barrel but velocities taken from a Noveske 18" AR.
My 18" Proof barrel will shoot the same velocity, and up to 2603 fps. With maximum loads of Leverevolution, the 115 gr DTAC seated out to 2.290 vs the 110 gr Atip, almost the same length, and seated at 2.245" have the same pressure and the 115 is 2593 fps, which is what Hornady recommended for their gas gun load data.
It has been working for me for years with 2 ARs with 18" Proof barrels.
Just the facts

Cascade Hemi · Thursday at 10:55 PM

45-90 said:
Here's the manual 110 gr Atip at 2575 fps in 18" AR gas gun Noveske Model N4 starting on page 239 of the Hornady manual. Not a test barrel but velocities taken from a Noveske 18" AR.
My 18" Proof barrel will shoot the same velocity, and up to 2603 fps. With maximum loads of Leverevolution, the 115 gr DTAC seated out to 2.290 vs the 110 gr Atip, almost the same length, and seated at 2.245" have the same pressure and the 115 is 2593 fps, which is what Hornady recommended for their gas gun load data.
It has been working for me for years with 2 ARs with 18" Proof barrels.
Just the facts

110 A-Tip is not 115 DTAC or RDF. The Hornady manual doesn't tell you difference between 108ELDM and 110A-TIP because the load data is for 108ELDM. 108ELDM is not 115 DTAC or RDF. There is no published load data for 6ARC with 115 DTAC or RDF. QL can gets pretty close to the Hornady 108ELDM data by adding case volume, within what I think the margin of error should be. Your 115 RDF recorded data still isn't even close to 52kPSI. 115 DTAC going 2603 is worse yet. This is SH though, where starting loads begin at 10kPSI over book.

Now mind you, I've recorded somewhere close to 100 Grendel combinations and QL is dead on. Reported 6ARC data here closely matches QL too. Your data? <chortle>

45-90 · Thursday at 11:28 PM

Cascade Hemi said:
110 A-Tip is not 115 DTAC or RDF. The Hornady manual doesn't tell you difference between 108ELDM and 110A-TIP because the load data is for 108ELDM. 108ELDM is not 115 DTAC or RDF. There is no published load data for 6ARC with 115 DTAC or RDF. QL can gets pretty close to the Hornady 108ELDM data by adding case volume, within what I think the margin of error should be. Your 115 RDF recorded data still isn't even close to 52kPSI. 115 DTAC going 2603 is worse yet. This is SH though, where starting loads begin at 10kPSI over book.

Now mind you, I've recorded somewhere close to 100 Grendel combinations and QL is dead on. Reported 6ARC data here closely matches QL too. Your data? <chortle>

First don't let your bias blind you...
Look at the photo it shows the same load data for the 108 gr and the 110 gr Atip
Here's a close up ....they are interchangeable in their load data.
I have quick load too...it's a prediction only..
It says so every time ya use it. Use loading manuals over Quick Load.
That is from the makers of the QL program.
I use its predictive software...too, as a guideline and when manuals are not available.
Bullet length and if the 110 Atip and 115 DTAC are almost identical the 5 grains in weight is not as significant as length, and I add .050" to that 110 gr COAL manual length when loading helps bring down the pressure on the 115 according to QL it will have slightly less pressure than the shorter COAL of the 110 gr.
The 115 gr RFD at 2550 fps and .634 BC is an excellent load for a 18" AR 15 probably hanging with most 16" 6.5 CM autos with factory loads.
Just the facts.

Cascade Hemi · Friday at 1:06 PM

45-90 said:
First don't let your bias blind you...
Look at the photo it shows the same load data for the 108 gr and the 110 gr Atip
Here's a close up ....they are interchangeable in their load data.
I have quick load too...it's a prediction only..
It says so every time ya use it. Use loading manuals over Quick Load.
That is from the makers of the QL program.
I use its predictive software...too, as a guideline and when manuals are not available.
Bullet length and if the 110 Atip and 115 DTAC are almost identical the 5 grains in weight is not as significant as length, and I add .050" to that 110 gr COAL manual length when loading helps bring down the pressure on the 115 according to QL it will have slightly less pressure than the shorter COAL of the 110 gr.
The 115 gr RFD at 2550 fps and .634 BC is an excellent load for a 18" AR 15 probably hanging with most 16" 6.5 CM autos with factory loads.
Just the facts.

I've shot all of these bullets and have first hand experience. I went ahead and measured their bearing surfaces for the sake of this thread. Here's the comparitor measurements, it should make it obvious why there's such a large difference in pressure and why A-Tip data doesn't work very well with RDF and DTAC despite the close weights.

108ELDM .474"
110 ATip .404"
115 RDF .520"
115DTAC .466"

LRRPF52 · Friday at 2:09 PM

Cascade Hemi said:
How long ago?

Hornady's load data conflicts with Sierra and Hodgdon, both of which match QL and user reported data on this site. Recent, and historical, reported data on Grendel forum also matches current QL. My own load data closely matches QL. Five years ago QL was really off for Grendel, after quite a few updates it is pretty spot on.

If they patched it recently, I would test it against the latest Hodgdon’s updates with CFE223, LVR, and 8208XBR under 123gr SMK.

It wasn’t long ago when I saw numbers that were way off, like what we’ve seen over the years. Maybe the poster was using a non-updated version of QL.

We have a pressure test breech that was calibrated over a 6-month period before considering any of the readings as reliable.

The data I saw for my 2012 pressure ladder, which were later pressure trace tested, match the new Hodgdon’s data to within a few hundred psi. Hodgdon’s is the first industry source I’m aware of to publish CFE223 and LVR data for Grendel.

Hornady published load data for it way back in the 9th Edition I think, but of course they don’t show pressures.

45-90 · Friday at 3:52 PM

Cascade Hemi said:
I've shot all of these bullets and have first hand experience. I went ahead and measured their bearing surfaces for the sake of this thread. Here's the comparitor measurements, it should make it obvious why there's such a large difference in pressure and why A-Tip data doesn't work very well with RDF and DTAC despite the close weights.

108ELDM .474"
110 ATip .404"
115 RDF .520"
115DTAC .466"

Give it up..
Hornady is wrong and you are right. LOL...
Comical, and presents as totally arrogant...boarding on pathetic...don't be that guy.

Hornady has the labs and test equipment and more money to spend on these products then any one person.

But somehow Hornady is wrong and that the QL you possess is right on, and better than anyone's QL program..
Because for some reason you do not like Hornadys results and can not accept reality of its outcome.
Or that QL is not an exact science but predictive software, as QL warns on your computer screen... that's exactly what it is...and to trust manuals with actual load data, over QL...facts.

I've shot all these bullets too. In 6 dasher and both 6 mm ARCs...so I have "first hand" experience with all of them too, as well as many thousands of others.

Hornadys data works for me as well as a million other firearm owners, go through their manual they lump bullets together where it does not have a great effect on pressure. Most Everyone knows about bearing surface and types of bullets.
I have even run a few tenths above maximum and never experienced any problem with the load data I've used from their manuals.
Bearing surface?... Here are some bullets with lots of bearing surface, all copper bullets I've developed load data for..." first hand" ...LOL.
Lots and lots of beating surface...so maybe I've learned something about bearing surface.... maybe I've even adjusted the bearing surface of the bullet.
Maybe I've made and altered extra long bullets and fired them...subjects of my own design.
Guys who want to shoot 350 grains 400 grs in an AR 15....and heavier as the caliber goes up.
So the 6mm ARC has better performance than you want it to...it beats your favorite cartridge... obviously... it can't do that, but it does.
Don't like it, don't whine, change cartridges and get better performance, there are lots of choices...and remember no one really cares, and none of it is really important.

Cascade Hemi · Friday at 4:15 PM

45-90 said:
But somehow Hornady is wrong and that the QL you possess is right on,

I clipped all the extra shit out because it's irrelevant. Hornady doesn't publish pressure data at all. Further, Hornady's test fixture isn't an AR15. I have never seen Hornady's 6ARC test fixture chamber pressures and neither have you. No one has besides Hornady. You probably are replicating their velocities, by all accounts it is in fact real. However, every bit of data from other sources, that includes pressure, conflicts with what Hornady considers a safe maximum load. On top of that, Hornady does not produce data for the 115 DTAC, or claim their data extends beyond what's in their book. If you take the time to measure the bullets it is plainly obvious why the pressure is different between A-Tip and DTAC. That difference is reflected in QL.

QL is in fact an estimation. Hornady's load data is also an estimation. They give you a warning at the beginning to work up.

I think I have explained it well enough. Anyone reading this is free to draw their own conclusions based on the discussion. You can have the last word and I'll move on.

45-90 · Friday at 8:36 PM

6 mm ARC, Hodgdon has the same max load on their load data site for the 110 ATip as the 107 SMK ...exactly the same powder charge at 28.2 gr of Leverevolution for both bullets.
Fact.
Similar weight, similar profile, uses the same max load for a bunch of cartridges in pressure tested data. Fact.

Hornady fires their pressure tested anmo in an AR 15 18" barrel to give one a realistic idea if what to expect in a production rifle...fact there is the photo pictured above...fact.

Hornady does not produce the 115 Dtac bullets so they will not produce load data for it. Duh...

But reloaders work up load data from similar bullets all the time, every day...
It's shared to those who care to learn, and work up for their chambers... Yahoo.

You have presented nothing but a silly argument that you and QL know better than Hornaday and now Hodgdon load data.
Which QL warns against...but you ignore that.

Hodgdon also states bullets of similar weight and length will have same exact maximum powder charge for certain powders...fact...including pressure data from Hodgdon.
You can look it up if you care to.

Finally you admit QL is an estimate... yes we all know... I use QL too...a useful tool but hardly exacting, as the QL manufacturers state and everyone knows, and finally agree QL is an estimate.
All load data should be worked up to for each individual rifle chamber and barrel, regardless if it's orgin, as powder lots are slightly different, as well as chambers & barrels.
It's up to the individual to determine if a reloaded round is safe in their rifles chamber.
Yeah I've been known to measure bullets too...as I modify and make them.
But does any of it matter...nope.

Gtscotty · Friday at 10:17 PM

Cascade Hemi said:
I clipped all the extra shit out because it's irrelevant. Hornady doesn't publish pressure data at all. Further, Hornady's test fixture isn't an AR15. I have never seen Hornady's 6ARC test fixture chamber pressures and neither have you. No one has besides Hornady. You probably are replicating their velocities, by all accounts it is in fact real. However, every bit of data from other sources, that includes pressure, conflicts with what Hornady considers a safe maximum load. On top of that, Hornady does not produce data for the 115 DTAC, or claim their data extends beyond what's in their book. If you take the time to measure the bullets it is plainly obvious why the pressure is different between A-Tip and DTAC. That difference is reflected in QL.

QL is in fact an estimation. Hornady's load data is also an estimation. They give you a warning at the beginning to work up.

I think I have explained it well enough. Anyone reading this is free to draw their own conclusions based on the discussion. You can have the last word and I'll move on.

You're still spreading your Hornady conspiracy nonsense, you've got commitment to your delusion, I'll give you that. It's rich that you try to draw a parallel between Hornady and your rough Quickload estimates as both... estimates, while holding Hodgdon as some other higher standard and pretending that Hodgdon and Sierra data match when they don't.

Quickload is sometimes close and sometimes way, way, off. It's impossible to have really done the shooting and comparisons you claim to have done and not know that. It would be really great if you could stop polluting every 6 ARC thread with your conspiracy theories, there's a risk that someone might think you know what you're talking about.

rlsmith1 · Friday at 10:41 PM

rlsmith1 said:
This that have a rifle length 14.5” 6.5 CM, what is your gas port size and what are you running for a buffer?

Whew, glad we got that science settled

Anyone have guidance on the above?

st1650 · 2025-02-01T00:24:03-0500

On the topic of large frame ARs ...

Why so little love for the 6creed, 22 creed, 6gt and 22gt ? Too soon ?
Seems like it would be easier to shoot than the 6.5 with 140s and give some extra velocity over the 6 & 22 ARC

45-90 · 2025-02-01T22:20:35-0500

st1650 said:
On the topic of large frame ARs ...

Why so little love for the 6creed, 22 creed, 6gt and 22gt ? Too soon ?
Seems like it would be easier to shoot than the 6.5 with 140s and give some extra velocity over the 6 & 22 ARC

I have quite a few large frame ARs in 308, 358, 6.5 CM, 338 RCM 8.6 Blk....I prefer the 308 in large frame as a general use gun.

Not even remotely interested in the calibers you mentioned. Or I'd own them.
I tend to like the AR 15 and its light calibers...for most stuff.
They get the job done for me and the extra velocity, and cost to produce it are not needed, along with the extra weight.
Plus AR 15s are easy to build and make shoot accurately for most anyone.
The standard 5.56 is all I need in 22 cal. AR. But have the 224 Valkyrie for heavy bullet loads, or 6mm ARC, or fast twist 450 Bushmaster and 502 gr bullets make good sub loads.
I prefer the AR 15 338 Spectre over the 8.6 Blk AR 10 for heavy subsonic loads....makes the newer 8.6 obsolete as a sub gun in my opinion, its way more accurate, single digit S/Ds, & light weight.

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MRGG-A (6.5 CM) vs 6 ARC?

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