This -><- close to choosing 6.8 SPC vs 6.5 grendel

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Originally Posted by pinzgauer

One thing to keep in mind is that all the 6.8 SPC figures people like to point to are the so-called SPC-II non-sammi variants. And some of the information being referenced in this thread is from people with a very strong vested interest in selling non-sammi barrels for 6.8. It is very clear to me they are no longer objective sources.

Your common inexpensive SPC from Remington or similar doesn't perform anything like that. And using the hot stuff in a barrel with the sammi throat is a recipe for high pressure problems.

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You're right about the original SPC chambers not allowing for the use of high performance ammo. To the best of my knowledge it's been many years since anyone has produced barrels using the old SPC chamber specs.

Remington did a very poor job designing the chamber because they were in a rush to get what they saw as a gold mine into the hands of the military. They were so driven by their desire to pump up their bottom line that upper management forced short cuts to be taken which neutered the potential of the cartridge. The chamber designs were unfinished and the barrel rifling was the same as the 6.8's parent round the .270 Win. All of this resulted in lackluster ballistic performance which is why the military didn't adopt the cartridge.

Remington abandoned their development efforts and these days the only ammo manufactured using the anemic ballistics of the original SAAMI approved 6.8 specs is that produced by Remington.

All of the design mistakes made by Remington have been corrected. The result is the SPC II which is a huge leap forward from the original design. In fact, I'm unaware of any manufacturers building anything using the old SPC designed chamber today.

Reloading manuals still show loads based on the SPC SAAMI specs. Folks that are into the 6.8 use the max loads in the those reloading manuals as their starting loads and work up from there. I imagine that at some point SAMMI will approve standardized SPC II specs. Obviously, you can't be a moron when working up handloads so be sure to read the manual to see if it specifies the loads as being SPC or SPC II.

The fact remains, the SPC flavor in wide usage is not sammi (saami?) You can't get vetted reloading information in published books, just over the internet from forums. And there is not an inexpensive bulk ammo source except in the sammi flavor.

Not the end of the world, especially if you're a hand loader. But it is a factor. It's especially ironic since one of the main criticisms of Grendel for years and years is that it was not sammi. Which Bill Alexander addressed.

As to Grendel bolts, I'm not a fan of the type 1 type 2 stuff. That is something one barrel manufacturer made up there was quite a bit of confusion over their barrels. It creates more problems than it solves.

There is one proper Grendel bolt dimension. The other flavor was just 762x39 cludges that were cheaply made out of 556 bolts. Which when machined out for the larger case diameter was too weak. You can get away with it for 762 x 39, but they couldn't handle Grendel pressures. (More accurately, both thrust)

For Grendel Bill Alexander started with the Colt bolt design for their 762x39 carbine which allowed for proper stress distribution and a beefier extractor. With only slight changes to the bolt lug radiusing to refine stress distribution that became the Beowulf & Grendel bolts and it is capable of handling their full thrust. And now of course 6 mm arc.

Before he went to h&k I had a chance to chat with Bill Alexander for some time at the NRA show. When talking about bolts he indicated they had not seen any bolt failures for over a decade, and they believe the early batch where they did see some issues was due to inconsistent heat treating.

As to military, the Serbian army adopted Grendel in their m17 which is an ak-70 variant. They call it 6.5x39 or 6.5x38.7. privy is the main ammo manufacturer, and that grendel ammo is available inexpensively to us in both full metal jacket and soft point form. I don't know if it remained just in special units or if it was mainstreamed.

Anyone who selects Grendel or SPC because of purported military usage is chasing a pipe dream.

The fact that Grendel has been significantly tested in AKs, can be made on ex-soviet Union tooling, and can occasionally be bought in AKs *is* significant.

Side note: though Serbia is not a NATO member nor desires to be, they do actively participate with nato. My IN Captain son jumped with them on a joint exercise in eastern europe a while back and accordingly is able to wear their wings. He has a few other foreign jump wings, but the Serbian ones are not common to get at all so that's what he wears.

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Originally Posted by pinzgauer

The fact remains, the SPC flavor in wide usage is not sammi (saami?) You can't get vetted reloading information in published books, just over the internet from forums. And there is not an inexpensive bulk ammo source except in the sammi flavor.

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Quite right. No ammo manufacturer will risk a lawsuit making ammo that is not within SAAMI spec. Handloading is the only way to maximize the potential of an SPC II chamber. It's a shame Remington screwed the pooch through inept management practices.

Still, the chart above doing an apples-to-apples comparison of ballistics shows the two calibers running neck-and-neck even with the 6.8 using SAAMI spec factory ammo. Just imagine how that picture would change if another another 200 fps were added to the 6.8 if its ammo were made to a hypothetical SPC II SAAMI spec
:dance3:

Given the overlap between the cartridges, I would be more concerned with the future availability of parts, magazines, ammunition, and components than any ballistic differences.

Andy

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Originally Posted by Steve_in_Allentown

Just imagine how that picture would change if another another 200 fps were added to the 6.8 if its ammo were made to a hypothetical SPC II SAAMI spec

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And also imagine if Grendel was hand loaded to maximum as well!

The current grendel saami spec is not pressure limited, it's set to maintain a reasonable bolt thrust.

Stronger bolts, or use in bolt guns allows for more steam in the loadings. (As does longer than AR mag length overall length)

This is gnats ass stuff

Myself and a bunch of others are extremely happy with the current Grendel factory loadings. Especially the hornaday amax and SST as they are extremely accurate yet not expensive. I'm not able to beat their accuracy level with reloading.

Add to that inexpensive steel case availability and it's a great combination.

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Originally Posted by pinzgauer

And also imagine if Grendel was hand loaded to maximum as well!

The current grendel saami spec is not pressure limited, it's set to maintain a reasonable bolt thrust.

Stronger bolts, or use in bolt guns allows for more steam in the loadings. (As does longer than AR mag length overall length)

This is gnats ass stuff

Myself and a bunch of others are extremely happy with the current Grendel factory loadings. Especially the hornaday amax and SST as they are extremely accurate yet not expensive. I'm not able to beat their accuracy level with reloading.

Add to that inexpensive steel case availability and it's a great combination.

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Factory Grendel ammo is pretty good, but you can definitely load/reload superior ammo. I would suggest that you hang around the 6.5 Grendel board for a while.

I jumped on 6.5Grendel just for the steel case ammo.
As cheap to shoot as commercial 7.62x39 or 5.45x39 (I run ARs in those calibers too) but IMHO kinda the best of both, a 123 gr. found that shoots flatter than 5.45. I shot a lot of surplus 7n6 but nowadays there’s more barrels/parts/mags for 6.5Grendel than 5.45x39. Once my pile of 7n6 is gone, I’m out, although that’ll be awhile.
So 6.5G satisfies cheapskates like me but still appeals to guys who want to precision reload as well...

As someone who has:

Noveske 6.8
LWRC Six8
White Oak Armament 6.8
AR Performance/Titan Armory 6.8

I am very happy with all of them, get what suits your purpose and don't worry what all the other kids have!

Hi All,

Thank you for all of the great responses.

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Originally Posted by Steve_in_Allentown

Just imagine how that picture would change if another another 200 fps were added to the 6.8 if its ammo were made to a hypothetical SPC II SAAMI spec

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That is handloaders adding powder until “pressure signs”, probably close to proof load pressure. Same thing the wildcatters did in development, then blamed Remington when they used an actual pressure test barrel.

I prefer the magazines, bolt head dia, and hunting bullet selection of the 6.8 myself. If I were medium long range target shooting the 6.5 would be a better choice (still way behind a 6.5 CM for real long range).

In reality they are both really good at getting a heavier than 5.56 bullet out to a reasonable distance, and both are equally limited to a practical/ethical range for hunting that is before trajectory becomes a deciding factor.