How could or should the 6.5 mm Grendel be improved?

[Bill Alexander]

Guardsman should not take my general disgruntled disposition as anything other than that. I do not intend to try and discourage the ( excellent) work he is looking at but this is my reality check. I enjoy seeing the discourse and even Stan never ceases to amaze me. I am sure that Guardsman was not aware of the actions that preceded and followed the meeting we attended. Why would he be? And without this disclosure my position would appear nothing but stubborn. I apologize.

During the work on the Grendel the case capacity was examined and the 7 mm BR case was necked to 6.5 to see how it would do. Within the constraints of the weapon the additional powder capacity was worthless unless the operating pressure was also raised.

If one is to consider a new rifle and ammunition to go forward, I would be inclined to abandon the Grendel concept unless it can be shown to work within the existing envelope. The rifle system is not scalable in a robust form so why struggle. You should be looking at an optimum operating pressure of 58,000 psi for the next generation of propellant now entering service.

[Variable]

I would disagree completely. We've spent a considerable amount of time making the Grendel better...better bullets, lots of experimentation with powder and primers, comparisons of brass between Lapua, Wolf, and Hornady, etc.

The real issue is trying to hit a target that doesn't really exist. Tell us what your goals are, tell us the parameters, and we'll be more than happy to help improve the Grendel, but you can't do that by telling us what you DON'T want. IE...we don't want a .308 size cartridge, we don't want .308 recoil, etc. You cannot define a standard with negatives.

Define it by saying:

We want MOA accuracy at 400 yards.

We want 800 foot pounds of energy at 1000 yards

We want recoil of 7 pounds or less.

We want 300 rounds of ammo to weigh 27 pounds or less.

(All of these numbers are completely spurious, but make my point. You can't define it on the backside.)

Give us end results and positive goals, and we'll be glad to help. We'll also be glad to say...You can't get there from here! We've told guys that the Grendel isn't really a 1000 yard competition cartridge. We've told guys you can't be competitive in F Class Open with the Grendel, (though I think in 600 yard matches it might be useful.)

But you can't ask us how to improve the Grendel with some nebulous goal. It doesn't work like that.

This. In spades, and to the Nth degree.

I seem to remember a forum member coming into this discussion several years ago suggesting that the Grendel case be slightly lengthened, and case capacity increased, with a slightly larger receiver set to get a little more performance out of it. Remember who that was?


Yeah: ME. After I stopped stabbing in the dark, and ran the numbers, I saw that there was no real benefit to going that route, especially after seeing that the Grendel case can already serve as a basis for pushing those velocities, but again, 200fps is not a significant velocity increase with high BC 6.5 projectiles. Run the numbers on a 16" barrel and a 24" barrel and see how miniscule the downrange performance differences are.

It's also interesting to see that Bill was asked to supply AR15 Grendels with the Wolf 123gr Soft Point, which is one of the worst bullets you could possibly use to demonstrate the capabilities of the 6.5 Grendel, and totally inappropriate for a military demonstration of course.

I wanted a super bolt, and barrel extension too. I wanted a hybrid AR15 with an R25 style upper lockup, but eventually I also had to admit to myself that it just wasn't worth the trouble, and would return very little usefulness.

[Guardsman26]

Bill,

Thanks for the response. I think we may be talking about two different meetings. I was referring to the one at Harper's Ferry. More to the point, I would be a fool to come onto the 6.5 Grendel forum pedalling 6.8 mm SPC. I was not. Besides, my understanding is that 6.8 mm SPC is a dead duck as far as all US Military departments are concerned. I was never advocating this round or any variation of it as an intermediate caliber option. I don't like it because it offers no better range than the NATO 5.56 mm M855. The fact that Saudi Arabia has bought 30,000 LRWC 6.8 mm SPC carbines is irrelevant.

On the contrary, I think people (including TSWG) are beginning to see the merits of the 6.5 Grendel. My belief, as I think I have been very consistent in stating, is that existing Grendel FMJ round does not quite match 7.62 mm at 1,000 metres in terms of velocity, retained energy, drop and trajectory. I don't have enough info to make an informed comment about lethality, but maybe Stan C's picture of a Grendel FMJ yawing after 7" of gel penetration suggests that there is scope to improve the design in this area. My overall view is shared by a number of military users and weapon manufacturers in the EU and USA. Either you buy this premise or you don't.

Another important point to make is that we're beginning to move beyond the AR15 / AR10 platform. LSAT may or may not proceed from where it is now, but polymer-cased ammunition is coming. If we do adopt case-telescoped ammunition, the paradigm changes. Since all legacy systems will be null and void, procuring this technology is an opportunity to optimise the caliber. So the requirement for an improved Grendel to fit the action length of an M4 goes away.

I think the requirement is very simple:

Unprotected human target: 600 metres
Protected human target (10 mm) 100 metres
Effective suppression to 1,200 metres

Wind drift, trajectory, drop, velocity and energy values should all be comparable to 7.62 mm.

So make a round that is a ballistic match and put it in the lightest package possible. Save at least 30% in weight.

[Howitzer]

My question is a very simple one: how should the 6.5 mm Grendel be improved. You're saying it's fine as it is. Fair enough, but so far no NATO or Western Army has adopted it. And it's been around for quite a while. What you achieved with the Grendel is amazing. I'm definitely a fan. I believe it deserves a wider audience, that's why I started this thread.

This statement really bothers me.. No nation has adopted it so it isn't the best cartridge available is that what you are insinuating? Simply because nobody is using it doesn't mean it isn't the best thing available, and I certainly wouldn't want to be on the opposing end of another nation using the Grendel. It is obvious that there are a lot of politics going on in these decisions and not all of them have the Soldiers best interest because if that was the case please tell me why they would choose the ACU pattern and why we are still wearing it.

Is the Grendel a 7.62? No. But it is best performing AR-15 cartridge available. If it was adopted I bet we would see a lot more expert marksmanship badges on our dress uniforms.

How can it be improved? Don't use Wolf Soft Point ammunition.

[stanc]

I would disagree completely. We've spent a considerable amount of time making the Grendel better...better bullets, lots of experimentation with powder and primers, comparisons of brass between Lapua, Wolf, and Hornady, etc.

Yes, you have. Poor wording on my part. Allow me to rephrase a few words:

It's usually a waste of time to ask people who are emotionally and/or financially invested in their pet cartridge for ideas on how to make a better cartridge.

Give us end results and positive goals, and we'll be glad to help. We'll also be glad to say...You can't get there from here! We've told guys that the Grendel isn't really a 1000 yard competition cartridge. We've told guys you can't be competitive in F Class Open with the Grendel, (though I think in 600 yard matches it might be useful.)

Okay. In Guardsman's most recent post he gave specifics on desired performance. If, as postulated, those goals cannot be achieved with 6.5 Grendel, would the notional "6.5 Super G" provide a sufficient MV increase to accomplish them?

[stanc]

If one is to consider a new rifle and ammunition to go forward, I would be inclined to abandon the Grendel concept...

In favor of what?

[stanc]

I don't have enough info to make an informed comment about lethality, but maybe Stan C's picture of a Grendel FMJ yawing after 7" of gel penetration suggests that there is scope to improve the design in this area.

Indeed. That's why about a year ago I was pleading for somebody to conduct gel testing with the pre-production Wolf FMJ load, to see if the different configuration offered any improvement in terminal ballistics over the Norma FMJ.

[bwaites]

Indeed. That's why about a year ago I was pleading for somebody to conduct gel testing with the pre-production Wolf FMJ load, to see if the different configuration offered any improvement in terminal ballistics over the Norma FMJ.

Its a basically useless proposition except for speculation, which is itself useless! Until there is an ACTUAL, REAL competition for a new cartridge, no one will spend the money to make the cartridge all it can be in a military capability.

[bwaites]

In favor of what?

A new cartridge and cartridge specific rifle! LOL!!!

[bwaites]

Yes, you have. Poor wording on my part. Allow me to rephrase a few words:

It's usually a waste of time to ask people who are emotionally and/or financially invested in their pet cartridge for ideas on how to make a better cartridge.

Okay. In Guardsman's most recent post he gave specifics on desired performance. If, as postulated, those goals cannot be achieved with 6.5 Grendel, would the notional "6.5 Super G" provide a sufficient MV increase to accomplish them?

In its current guise, no. BUT....with a SuperPerformance powder, that might be changed.

Someone would have to pick a currently nonexistant projectile and develop a powder designed specifically for that powder, like Hornady did with the Amax, and it might be doable. BUT...no one has a reason to do so.

As for loadout weight, what is the Grendel cartridge weight currently vs .308? And 70% using which version of 7.62x51, M118? or ?

[JASmith]

...I think the requirement is very simple:

Unprotected human target: 600 metres
Protected human target (10 mm) 100 metres
Effective suppression to 1,200 metres

Wind drift, trajectory, drop, velocity and energy values should all be comparable to 7.62 mm.

So make a round that is a ballistic match and put it in the lightest package possible. Save at least 30% in weight.

This is an excellent step forward!

The word "comparable" when attached to drift, trajectory, velocity, and energy gives latitude for trades.

The remaining quibbles are:

• Protected Human Target (10 mm) at 100 metres
• "Effective Suppression to 1,200 meters"

One presumes 10 mm refers to armor of some sort. Are we referring to mild steel, a specific hardness of armor steel, or a ceramic plate? What is required in the form of wounding capability after perforating the protection? Holes in a 3mm Aluminum plate placed 100 mm behind the barrier? Something else?

How do we define "Effective Suppression?" As it stands the term is subjective. I have some thoughts but would prefer to work the speculation through the PM mode.

[Bill Alexander]

In favor of what?

I am not exactly sure at present. The result will stem from the target definition and the hit probability ie the required carried kills.

Gut says maybe a 6.5 but i would prefer a 7. Keep the OAL short and then work back to the case volume for the optimum operating pressure at an acceptable fill level with the new powders.

Grendel in the legacy M4 runs at too low a pressure to best utilize the case. I would want to push this up. The technology for this is simple and the bolt/barrel extension geometry is not a problem. The extension/barrel interface might need some massaging to hold up at elevated temps. In a new rifle this is easy stuff and the weight spiral is non existent as long as the mag length is constrained.

[Bill Alexander]

Indeed. That's why about a year ago I was pleading for somebody to conduct gel testing with the pre-production Wolf FMJ load, to see if the different configuration offered any improvement in terminal ballistics over the Norma FMJ.

The Norma is a target bullet and it is absolutely rubbish in gel.

If I was to look at the problem I would prefer to see generalization above specialization. Think blind to barrier AP with a smattering of anti personnel thrown in. First rule is always hit the target and make a hole in it. I like to see things that are velocity insensitive even if they do not look that pretty in formal gel testing.

The pre production Wolf was not this level. It was an unhappy projectile and all the work would yield would be an unsatisfactory result.

[Bill Alexander]

This is an excellent step forward!

The word "comparable" when attached to drift, trajectory, velocity, and energy gives latitude for trades.

The remaining quibbles are:

• Protected Human Target (10 mm) at 100 metres
• "Effective Suppression to 1,200 meters"

One presumes 10 mm refers to armor of some sort. Are we referring to mild steel, a specific hardness of armor steel, or a ceramic plate? What is required in the form of wounding capability after perforating the protection? Holes in a 3mm Aluminum plate placed 100 mm behind the barrier? Something else?

How do we define "Effective Suppression?" As it stands the term is subjective. I have some thoughts but would prefer to work the speculation through the PM mode.

If we can flesh out this then there is the beginning of a spec to work to.

[stanc]

Its a basically useless proposition except for speculation...

I disagree, Bill. All we have now is speculation and wishful thinking regarding how early a 6.5mm FMJ can be made to yaw in gelatin.

Testing the pre-production Wolf FMJ would've given us another data point in the knowledge base, and thereby provided a better basis for judgment.