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/2011/11/0...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." (www.ar15.com/forums/t_2_453/209394_Steel_Case_.html&page=1#i1882699);

6.5mm Grendel, 20-inch barrel:
100 gr WOLF FMJ -BT, 2,600 fps.
(http://www.ar15.com/forums/t_3_121/64961...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?

[stanc]

Well, I'm not about to call Bill or anyone anything (Cory wasn't either), because he is a pretty factual guy.

Bill says it's been measured at 50k psi. Cory says it's actually 10k psi lower. How is that not saying Bill isn't telling the truth?

Losing 10 grains of projectile weight while also losing over 200 feet per second would seem to be a bit odd.

I fully agree.

[cory]

Bill says it's been measured at 50k psi. Cory says it's actually 10k psi lower. How is that not saying Bill isn't telling the truth?

No that's not what I said.

JASmith was kind enough to run some numbers through quickload.

Per JASmith

My experience with the powder survey utility in QuickLoad is that the numbers generally come out fairly close to the velocities generally reported for safe loads with a particular bullet. A note of caution, however, is that QL results can frequently vary from published pressures by 5,000 psi and velocities by 200 fps when modeling particular loads. Hence QuickLoad is best viewed as a tool for developing insight rather than specifying particular load recipes.

I don't think anyone here doubts Bill A in the least. Those numbers show that the load could have been accomplished at anywhere from a 39ksi to a 50ksi load. This supposts both what I said in this thread and what Bill A has told us.

Back to the Wolf ammo. It appears to have been developed with an ultraconservative load. You'd think in 8 years of development they could have refined their analysis and design, allowing a less conservative choice.

With recent events I wonder if they hadn’t already made a substantial order of powder for the 110gr steel core projectile, and then had to switch the projectile last minute because of the ruling on the 5.45 ammo. Rather than going back to the drawing board, selecting a new projectile, and selecting a powder for the projectile, they may have selected the new projectile based on the powder in hand.

[stanc]

No that's not what I said.

I don't think anyone here doubts Bill A in the least. Those numbers show that the load could have been accomplished at anywhere from a 39ksi to a 50ksi load. This supposts both what I said in this thread and what Bill A has told us.

Did you not say that the Wolf ammo is 10k psi below SAAMI spec? Bill said it tested at ~50k psi. You can't both be right.

With recent events I wonder if they hadn’t already made a substantial order of powder for the 110gr steel core projectile, and then had to switch the projectile last minute because of the ruling on the 5.45 ammo. Rather than going back to the drawing board, selecting a new projectile, and selecting a powder for the projectile, they may have selected the new projectile based on the powder in hand.

As I previously noted, a year and a half ago Bill posted that Barnaul planned to use a 100gr -- not 110gr -- steel-core FMJBT bullet. Weight of the current bullet is unchanged from that of 2012.

Try again.

[cory]

Did you not say that the Wolf ammo is 10k psi below SAAMI spec? Bill said it tested at ~50k psi. You can't both be right.

As I previously noted, a year and a half ago Bill posted that Barnaul planned to use a 100gr -- not 110gr -- steel-core FMJBT bullet. Weight of the current bullet is unchanged from that of 2012.

Try again.

As you so elegantly like to point out to us, you should read the post again.

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

This load may be a 50ksi load. However, QL shows us that 2600fps with a 100gr projectile can be had with a different powder at 39ksi (theoretically). Therefore there is 10+ksi that has been left on the table. That is not the case for the loads you want to compare it to.

[nincomp]

We already know the potential of the round from the current commercial loadings. That gives us enough info for its use as a Universal Infantry Cartridge.

If indeed the Wolf ammo will arrive in the next year (yeah, I know that we have heard this before) I think that we should not gripe too much about non-optimal performance. If indeed its accuracy is in the 2-3 MOA range, it is going plenty fast for the distances in which it will be used. By that, I mean a 2-3 MOA round is would not be the first choice for high precision 600+ yard shooting anyway.

The velocity of the supplied samples is lower than some (more expensive) commercial loadings. This simply means that there is plenty of potential left for a "New Improved" loading from Wolf.


This message has been provided by the Glass-Half-Full Society.

[stanc]

This load may be a 50ksi load. However, QL shows us that 2600fps with a 100gr projectile can be had with a different powder at 39ksi (theoretically).

I don't give a crap about theoretical calculations for different powders. I'm only concerned with what has actually been achieved in reality with the Wolf ammo. If its pressure has been measured accurately as 50k psi, then it is not 10k psi lower than SAAMI spec.