Grendel as a Universal Infantry Cartridge

[stanc]

Re: Wolf steel-case 100gr FMJ ammo

Excerpted from David Fortier's post on arfcom:

16 inch barrel
Average of 10 shots
2496 FPS
Extreme Spread
35 FPS
Standard Deviation
11 FPS

100 yard accuracy.
Average for three 10-shot groups is 2.4 inches.

How does this accuracy compare to that of US military 5.56 M855 Ball?

Is this accuracy and velocity adequate for comparison testing of 6.5 Grendel vs 5.56 and 7.62 NATO?

Is performance of the Wolf FMJ ammo good enough to permit an evaluation of 6.5 Grendel as a Universal Infantry Cartridge?

[cory]

Excerpted from David Fortier's post on arfcom:

How does this accuracy compare to that of US military 5.56 M855 Ball?

Is this accuracy and velocity adequate for comparison testing of 6.5 Grendel vs 5.56 and 7.62 NATO?

Is performance of the Wolf FMJ ammo good enough to permit an evaluation of 6.5 Grendel as a Universal Infantry Cartridge?

Is that a serious question? Which military loading for either of those platforms is 10ksi below their SAAMI Spec?

[stanc]

Is that a serious question?

Certainly.

Which military loading for either of those platforms is 10ksi below their SAAMI Spec?

What makes you think that the 6.5 Grendel FMJ ammo is 10kpsi below SAAMI spec?

The load pressure is in accordance with SAAMI with the typical loaded round presenting 49,000 to 50,000 psi as sampled at STP on a new batch.

[cory]

Physics.

[stanc]

Would you care to elaborate?

[cory]

Would you care to elaborate?

Like you can't get velocity for free, you can't give it away either.

To get more velocity it takes more pressure, henceforth less velocity equals less pressure.

Maybe someone with quickload could run the numbers to see what the software says the pressure should be.

[stanc]

Like you can't get velocity for free, you can't give it away either.

To get more velocity it takes more pressure, henceforth less velocity equals less pressure.

So, effectively you're saying that Alexander is either lying or stupid.

[explorecaves]

I believe cory was referencing the wolf ammo being under pressured/loaded light....

[stanc]

I believe cory was referencing the wolf ammo being under pressured/loaded light....

I realize that. See post #288.

[explorecaves]

As I understand cory's post, neither of the mil-spec caliber loadings referenced are 10kpsi under pressured. Thus the wolf ammo would be at an automatic disadvantage as it is typically loaded light (probably in the range of 10kpsi light). Ergo, it would not be "good enough to permit an evaluation of 6.5 Grendel as a Universal Infantry Cartridge."

[stanc]

As I understand cory's post, neither of the mil-spec caliber loadings referenced are 10kpsi under pressured. Thus the wolf ammo would be at an automatic disadvantage as it is typically loaded light (probably in the range of 10kpsi light).

You gotta be kidding. Did you not read post #288???

Here, I'll make it easy for you:

The load pressure is in accordance with SAAMI with the typical loaded round presenting 49,000 to 50,000 psi as sampled at STP on a new batch.

[Drifter]

Is Bill A's reference to a "new batch" at 50k psi the same as what Fortier tested?

[stanc]

It would seem so, judging by context. Click on the (little blue) link symbol to the right of "Bill Alexander" in my previous post, if you wish to read his entire post.

[SHORT-N-SASSY]

. . . To get more velocity it takes more pressure, henceforth less velocity equals less pressure. . . .

To recap:

6.5mm Grendel SAAMI Maximum Average Pressure (MAP): 52,000 psi (http://kwk.us/pressures.html);

6.5mm Grendel, 20-inch barrel:
100 gr Alexander Arms Berger Open-Tip Match: 2,847 fps;
123 gr Alexander Arms Lapua Scenar: 2,627 fps;
123 gr Hornady A-MAX: 2,582 fps.
(http://www.rifleshootermag.com/2011/...del-evolution/);

"It is a double base ball type and will be loaded to 3550 bar [51,488 psi] in line with existing weapon and ammunition setup." (https://www.ar15.com/forums/t_2_453/...age=1#i1882699);

6.5mm Grendel, 20-inch barrel:
100 gr WOLF FMJ -BT, 2,600 fps.
(http://www.ar15.com/forums/t_3_121/6...pic_IN_OP.html).

The big question: In view of the above, how do Alexander Arms and Hornady, loading their respective 6.5mm Grendel ammo, operating at approximately the same chamber pressure as WOLF, and using projectiles that weigh 23% greater than the 100-grain projectile used in the WOLF 6.5mm Grendel Steel Case ammo, manage to achieve approximately the same muzzle velocity --- from the same 20-inch barrel length?

[Variable]

Well, I'm not about to call Bill or anyone anything (Cory wasn't either), because he is a pretty factual guy. I am curious as to where the disparity comes from though.


Losing 10 grains of projectile weight while also losing over 200 feet per second would seem to be a bit odd. I still want it (so long as it cycles my rifles well), but where did the energy go?