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 · Monday at 7:22 PM

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 · Monday at 7:41 PM

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 · Monday at 7:48 PM

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 · 2025-01-21T13:59:13-0500

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 · 2025-01-21T16:33:34-0500

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.

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MRGG-A (6.5 CM) vs 6 ARC?

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