Part II of "Requirements for replacements of currently issued 5.56 M-855 and 7.62 M-8

[stanc]

Here's a rough draft of a lethality description. I felt guilty about arguing about testing without moving forward.

Yeah, well...I really should have taken my posts about 6.5G testing to a different thread. It's just too eeeeeasy to reply to someone off topic in the same thread. :o

So, I banged this next one out and am putting it on the wire early so folks can through some stones:

Requirement 3: Lethality

Threshold: Bare Gelatin

[INDENT]Penetrate at least 30 cm into bare gelatin conforming to the FBI Test 1 description with the average width of the permanent cavity at least 2. cm over at least 10 cm using a bullet design conforming to the NATO interpretation of Hague and Geneva conventions.[/INDENT]

Rationale: This threshold requirement makes the bullet lethality at least equivalent to the 7.62X51 M80 round in the first 30 cm of penetration.

For equivalent performance, shouldn't the wording be something like "...the average width of the permanent cavity at least 2.0 cm, over a distance of 20-35 cm into the gel block..." ?

Objective 2: Robust wound channel

Penetrate at least 40 cm into bare gelatin with the damage channel being greater than 2.0 cm in maximum dimension within 10 cm of the entry.

Rationale: Specifing the width of the damage channel at 10 cm means that the channel will almost certainly be starting to open at about 5 cm into the gelatin block.

This seems like an unrealistic expectation to me. The fastest yawing FMJBT bullet appears to be the 5.45x39 M74, which has onset of yaw at ~7cm. IIRC one of Fackler's articles, the reason that happens is imbalance caused when the lead plug in front of the steel core flows assymetrically upon impact. Since lead is verboten for the next generation military bullets, it's questionable if yaw can be made to happen at 7cm, let alone 5cm.

Judging by Fackler's wound profile drawings, it looks as if the best that might be achieved -- with FMJ bullets having lightweight material (such as aluminum) in the nose, to shift CG rearward -- is onset of yaw at ~10cm, as with the .303 MkVII round.

FWIW, non-fragmenting FMJ rifle bullets typically penetrate about 60cm into gelatin, so specifying 30-40cm is hardly a challenge.

[JASmith]

Concur -- we need tests!!

...it's questionable if yaw can be made to happen at 7cm, let alone 5cm.

Judging by Fackler's wound profile drawings, it looks as if the best that might be achieved -- with FMJ bullets having lightweight material (such as aluminum) in the nose, to shift CG rearward -- is onset of yaw at ~10cm, as with the .303 MkVII round...

Kinda looks that way to me too. On the other hand, the words we're referring to are in the objective statement. Hence we are allowed to push the edge of do-ability since no harm accrues to a contestant for falling short -- unless a competitor finds a way to make it happen!

The project would be in real trouble if we write a threshold statement that no solution could meet! So, the rule of thumb is:

• Threshold = doable within reason while satisfying all the other thresholds.
  
• Objective = can be a stretch if remotely in reach. These help spell out what we really want but aren't sure they're doable. (Shouldn't write them if we know they are out of reach!)
  

FWIW, non-fragmenting FMJ rifle bullets typically penetrate about 60cm into gelatin, so specifying 30-40cm is hardly a challenge.

I think the 40cm in the objective was a typo. I was thinking of a half-meter, which is a tad more than two feet. Have corrected the statement in post #18 above.

The real question is -- can we identify a payoff for penetrating deeper than 50 cm?

[stanc]

The real question is -- can we identify a payoff for penetrating deeper than 50 cm?

IMO, only psychological. Considering the thickness and width of most combatants' torsoes, there seems to be no physiological need to penetrate more than 30cm of gelatin.

However, if soldiers compare penetration to 60cm of 7.62 M80, they may perceive 50cm (or less) to be lacking in lethality.

[JASmith]

Returning to post #18 of this thread, we can infer that proving the superiority of one caliber/bullet/cartridge poses a significant challenge when we consider the posts by bwaites: Stopping power by Caliber (http://www.65grendel.com/forum/showthrea...by-Caliber) and http://www.65grendel.com/forum/showthrea...ber-Part-2.

Consider this extract of percentage of one-shot stops:

[INDENT]25 ACP 30%
22 Rim 31%
32 ACP 40%
380ACP 44%
38 SPC 39%
9mmLug 34%
357Mag 44%
40 S&W 45%
45 ACP 39%
44 Mag 59%
Rifle 58%
ShotGn 58%[/INDENT]
It's hard to get better than the 50-60% suggested by the rifle and shotgun statistics.

This data may suggest we recast the gelatin test to reflect the performance of a the FMJ 9mm at the muzzle as the threshold and that of the 7.62X51 M80 as the objective. The range(s) we would require these degrees of lethality also need to be discussed.

This combination would allow some differentiation based on the statistics presented and possibly avoid an arbitrarily high threshold on cartridge lethality.

[stanc]

Returning to post #18 of this thread, we can infer that proving the superiority of one caliber/bullet/cartridge poses a significant challenge...

Yes, indeed it do. I don't know if quantifying gel test results can even be done satisfactorily.

...consider the posts by bwaites: Stopping power by Caliber (http://www.65grendel.com/forum/showthrea...by-Caliber) and http://www.65grendel.com/forum/showthrea...ber-Part-2.

Consider this extract of percentage of one-shot stops:

[INDENT]Rifle 58%[/INDENT]

It's hard to get better than the 50-60% suggested by the rifle and shotgun statistics.

IMO, his one-shot-stop % is a rather meaningless figure.

A better measure is his % actually incapacitated by one shot:

[INDENT]Rifle 80%[/INDENT]

This data may suggest we recast the gelatin test to reflect the performance of a the FMJ 9mm at the muzzle as the threshold and that of the 7.62X51 M80 as the objective.

This combination would allow some differentiation based on the statistics presented and possibly avoid an arbitrarily high threshold on cartridge lethality.

I think I see your reasoning, but it seems to me that 9mm FMJ is much too low for threshold. Wound profile of 9mm FMJ is not even as good as that of .30 Carbine, which can easily be exceeded by most military rifle calibers.

FWIW, I consider his stopping power data too flawed -- or at least incomplete -- for this purpose. For one thing, it does not tell us what the difference in performance is between FMJs and JHP/JSP expanding bullets. Since this thread is concerned with military rifle Ball ammo, the numbers for JHP/JSP rounds would have to be deleted, something we can't do with the posted summary.

Also, he does not tell what % actually incapacitated by one shot weren't fatal, which (IMO) would be a far more reliable indicator of effectiveness. Any bullet will "incapacitate" by killing; it's when a torso hit is not immediately fatal that incapacitation becomes important.

[JASmith]

...A better measure is his % actually incapacitated by one shot:

[INDENT]Rifle 80%[/INDENT]...Any bullet will "incapacitate" by killing; it's when a torso hit is not immediately fatal that incapacitation becomes important.

The qualifier for "actually incapacitate" is that the shot hit the head or torso. Consider the .25 ACP statistic for example:[indent]

% actually incapacitated by one shot (torso or head hit)- 49%

[/indent]
This tells me that a hit in the torso or head takes one out of action about half the time or better, even with a pipsqueak caliber/cartridge. The issue is how the statistics were derived.

The questions you raise are best resolved by sending them to the author of the study. He might even have a soft spot where things Grendel are concerned...

In the meantime, this is the best set of statistics I've seen in the open literature.

The pucker factor for a 7-yard shot is a lot greater than it is for a 500 meter shot. So, in my view, the 9mm (or M1 Carbine) equivalent threshold is best applied at some distance from the shooter.

So, struggling for an understandable description, one could say that: "The wound channel for a gel target hit at 500 meters must be at least as large in major cross-section and depth as that of a 9mm FMJ hitting the same block 1.5 meters from a block of the same specifications."

I would happy to replace "M-1 Carbine" for "9mm" in the above.

[stanc]

The qualifier for "actually incapacitate" is that the shot hit the head or torso.

True. That's why in my conclusion I said "he does not tell what % actually incapacitated by one shot weren't fatal, which (IMO) would be a far more reliable indicator of effectiveness."

Consider the .25 ACP statistic for example:[indent][/indent]
This tells me that a hit in the torso or head takes one out of action about half the time or better, even with a pipsqueak caliber/cartridge. The issue is how the statistics were derived.

Precisely my point. He doesn't differentiate between "incapacitation" by killing and non-fatal incapacitation.

The questions you raise are best resolved by sending them to the author of the study.

In the meantime, this is the best set of statistics I've seen in the open literature.

That may be, but it doesn't overcome the flaws in the data he presents. Remember, GIGO.

The pucker factor for a 7-yard shot is a lot greater than it is for a 500 meter shot. So, in my view, the 9mm (or M1 Carbine) equivalent threshold is best applied at some distance from the shooter.

So, struggling for an understandable description, one could say that: "The wound channel for a gel target hit at 500 meters must be at least as large in major cross-section and depth as that of a 9mm FMJ hitting the same block 1.5 meters from a block of the same specifications."

I would happy to replace "M-1 Carbine" for "9mm" in the above.

No need.

P.S. I do think inserting 9mm (or .30 Carbine) performance into the requirements is likely to cause confusion in those reading a document about potential replacements for 5.56 and 7.62 NATO.

[JASmith]

...I do think inserting 9mm (or .30 Carbine) performance into the requirements is likely to cause confusion in those reading a document about potential replacements for 5.56 and 7.62 NATO.

You just hit on part of the reason I mentioned the M-1 Carbine as a possible threshold -- as you helped us understand, this "little guy" actually does tumble and you've sent us a neat picture of the permanent cavity in gel.

So, as in the earlier draft, we ask that the major cross section of the wound cavity be at least a specified dimension. The FMJ bullet tumbles, so the length of the bullet becomes the basis for the threshold. The Speer 110 gr TMJ 30 Carbine bullet is shown as having a length of 0.676" in the JBM "Lengths" Library. So, we take approx 90% of the length and require that the maximum width dimension be at least 0.6" on average over at least (a guess) 5" of the permanent gel cavity.

We'll need to mensurate the picture you posted but you get the idea...

This gives as a measurable quantity that is based on arguably questionable statistics and actual performance of a surrogate.

I wonder if Bill can approach the author to get more detail about the statistics?

[noone]

I find the one shot stop statistics quite interesting. I think they are most useful for those who only plan on firing one shot. I would like to find some statistics on two or three shot stops, and some statistics on shot placement and find out what those tell us.

If 95% of firearms stop someone with two well placed shots, they it would stand to reason that using the firearm that allows you to get those two well placed shots placed properly as quickly as possible (like a 32 auto, or 9mm VS 45 or 44) would be the way to go.

In the end though, I think that people will continue to disagree (bicker or argue sometimes) about which statistic backs up their favorite belief the best.

I'll continue carrying a 45ACP as a primary pistol, with a small backup pistol. For rifle, although I seldom carry one for "self protection" any longer, I think the 6.5 Grendel and it's offshoots loaded with a 120 grain bullet and similar weights will be hard to beat for all round speed for close engagements, actual power on target, long range accuracy and power, and reasonable weight for the system and ammo.

Sure, the 308 has more power, and the 338 has even more than that. And the 5.56 weighs less with a basic ammo load. But as an overall compromise, the Grendel and the 45ACP are hard to beat.