FMJ yaw and upset performance

[JASmith]

LRRPF52,

Thanks for the excellent clarification!

Your discussion helps sharpen my thinking! I lean toward finding a cartridge that can take the near-muzzle lethality of the M855 and push that lethality level out to slightly beyond where one can reasonably expect to get reliable hits. For some, that range is about 7 meters, for others it is much further, but enough folks would like to see 400-500 meters that this makes a good starting point for discussions.

There's a lot in terminal effects on humans and real-world barriers that we just can't accurately model. That's why I try to use metrics like momentum and energy density coupled with a reasonable lethality metric. My favorite is the product of the bullet mass and the bullet momentum density to give a measure of penetration depth (momentum density) and material available to create a permanent wound channel (the mass part of the expression).

The bullet design is also important, but the critical first step is to assure that it has the right combination of mass and velocity so that the design can work!

Anecdotal observations like yours go a long way toward anchoring the though processes. Thanks again!

[stanc]

It would be nice to have a Lightweight Belt-fed Machinegun in Grendel to replace the M240 GPMG for dismounted soldiers, if a lower-cost bullet could be made for it with a long tracer endurance like the 7.62 tracer.

I don't know for sure what trace distance might be possible with 6.5 Grendel, but some indication might be had from that of 6.5x55 m/41 tracer, shown as 800 meters:

http://www.amkat.se/index.php?Env=Ammo&Menu_A=30&Menu_B=60&Menu_C=20&Menu_Value_A=6,5x55&Menu_Value_B=Tracer&Menu_Name=Tracer

As for a "lower-cost" ball projectile, that's another question. If the US Army stays with the exposed-penetrator configuration of 5.56 M855A1 and 7.62 M80A1, a similar 6.5mm bullet would have similar cost.

Attached: 5.56 M855A1 / 6.5 "M2065A1" / 7.62 M80A1

[LRRPF52]

Stan,

My opinion is that this whole push for environmentally-friendly ammo is simply the entrenched communists within our national "leadership" using the economic warfare angle against us under guise of environmental friendliness. Regardless, Joe will have what he has to do the job. I have no issues with M855 as it is for general use. Designated Marksmen should have Mk262 available to them.

The longer 6.5 bullets could provide the same tracer burn or comparative to 7.62 NATO, and 800m will cover most engagements with the belt-fed guns, but will require a longer bullet to house the magnesium for a good burn. A larger bolt with 3 huge lugs like the Sako 75 would help run a higher pressure load if the Grendel were used in a belt-fed MG. Since there are so many restrictions on machinegun ownership, we are limited in how much RDT&E we can do because of the costs associated with obtaining an 07 mfg license under an FFL, whereas we can tinker around with this cartridge in our AR's all day long.

As far as future assault rifles go, I don't think we should get so hung up on the caliber for that, especially as the trend moves to more and more modular systems with caliber-change options that can be determined by the purchasing authority of whoever is buying them (read as countries, not subordinate commands). As for the US, I think the M4 works great, but just needs a rifle-length free-float tube and the A1 trigger mech. That burst system has got to go. The focus should really be on reducing weight for the guys carrying belt-fed weapons, and something like the Grendel seems to show promise in at least providing a replacement for the current 7.62 NATO GPMG's, and maybe even the SAW at the same time.

I say this having carried and employed the M60, SAW, and M240 at different stages in my career-all from a dismounted perspective where it was SOP to distribute linked 7.62 to other members of the Platoon or Squad. 100rds of linked 7.62 weighs at least 7 lbs, and the basic load for the gun was usually 800-1200 rounds for the 2-3 man gun team. Units in the Afghanistan AOR that conduct dismounted patrols have been sacrificing basic loads due to the weight of the IBA, plus the thin air in many high altitude locations. When guys from the 505th PIR got back from their deployment there in 2002, they briefed us in the 325th AIR on their kit selection, and said that they actually were reducing the basic load of riflemen significantly to cut weight.

LRRPF52

[LRRPF52]

LRRPF52,

Thanks for the excellent clarification!

Your discussion helps sharpen my thinking! I lean toward finding a cartridge that can take the near-muzzle lethality of the M855 and push that lethality level out to slightly beyond where one can reasonably expect to get reliable hits. For some, that range is about 7 meters, for others it is much further, but enough folks would like to see 400-500 meters that this makes a good starting point for discussions.

There's a lot in terminal effects on humans and real-world barriers that we just can't accurately model. That's why I try to use metrics like momentum and energy density coupled with a reasonable lethality metric. My favorite is the product of the bullet mass and the bullet momentum density to give a measure of penetration depth (momentum density) and material available to create a permanent wound channel (the mass part of the expression).

The bullet design is also important, but the critical first step is to assure that it has the right combination of mass and velocity so that the design can work!

Anecdotal observations like yours go a long way toward anchoring the though processes. Thanks again!

JASmith,

All I know is that when I pick up an M4 or AR in 5.56, I have respect for the capacity it has to do some seriously ugly damage or lethality, especially if using thin-jacketed M193 and M855 or similar loads on the hotter end of the scale. Most soldiers are not able to make 400m hits with RDS-equipped sticks in a dynamic scenario with stress, which is why belt-fed weapons and Designated Marksmen or Sniper Teams shine at those distances. What I saw over several different light infantry units was that only about 25-50% of Infantry soldiers could reliably make the 300m hits on the standard qualification range in fairly stress-free conditions with recently-zeroed weapons in sunny weather and fresh chow in their guts.

Maybe magnified optics increases that hit probability, but we were using Elcans on the M240's and SAWs back then, which worked out well, except for the weight. I saw guys in Ranger Regiment who would mount 4x ACOG's on the 240's, which is a much lighter solution than the M145 Elcan. I just start to naturally lean to discussing belt-fed weapons again without even intending to when we talk about those distances, unless we're talking about DM's and Sniper Teams, which usually located themselves with the support-by-fire position where the 240's were located for planned attacks at the Platoon or higher level. If I had not spent 10 years with dismounted Infantry and Airborne units, I think my posts would look entirely different than they do, focusing more on the caliber solution, versus a holistic solution that includes training and employment, weapons, equipment, doctrine, procurement, RDT&E, mindset, etc. That is not meant to distract from the equipment/weapons portion of the solution in any way, but it helps to have the context in mind that these weapons will be employed in before jumping the gun. I just wish we could be testing a Grendel LMG right now...

LRRPF52

[JASmith]

LRRPF52,

There are others who share your views on the holistic approach. In spite of the impression given by my comments, I am one of them, although my technical R&D background would lead me to describe the interrelationships terms of interrelated systems.

Cheers!

[VASCAR2]

Regardless of which firearm is being employed I think the projectile and velocity is maybe slightly behind the users ability to employ the weapon effectively. I put a lot more emphasis on training and tactics than a particular bullet in most cases from a law enforcement perspective. One shooting I'm familiar with involved a local officer armed with a 20" barrel AR 15 with 55 grain ballistic tips. The subject was running and the round penetrated the subject in the buttocks area whereupon the subject fell to the ground. The subject then became compliant and was taken into custody even though this varmint bullet exhibited varmint bullet penetration and tissue destruction. This subject fully recovered from being shot with no permanent disability. Personally I like some of the newer bonded core JSP bullets which are now employed by a lot of police departments. From all my research the 5.56 in use by US police has been very effective where most subjects are stopped. I think the bonded core bullets are penetrating barriers like automobiles better than some of the older designs. I think the 6.5 G would make an excellent LE cartridge but I just don't see it happening when the 5.56 has been a big step up in performance for the local uniformed or tactical police officer in the US. With the lack of funding and training budgets I can't see LE transitioning to a different rifle/carbine caliber anymore than the US military. From my personal experience I felt a lot better armed with my 16" AR 15 than any other weapon I'd previously employed as a LEO. I would have gladly used my 16" 6.5 Grendel AR but I felt fortunate to have an AR15 in 5.56 the last few years where I was permitted to carry this weapon. The 5.56 with the proper ammo probably makes a better LE weapon than it does a Military weapon due to the fact LE departments don't have to comply with the Hague convention rules on bullet design which are a crock!

[stanc]

The longer 6.5 bullets could provide the same tracer burn or comparative to 7.62 NATO, and 800m will cover most engagements with the belt-fed guns, but will require a longer bullet to house the magnesium for a good burn.

Since there are so many restrictions on machinegun ownership, we are limited in how much RDT&E we can do because of the costs associated with obtaining an 07 mfg license under an FFL, whereas we can tinker around with this cartridge in our AR's all day long.

Yeah. One way it might be possible to tinker with a belt-fed is maybe conversion of an RPD or Czech vz52 LMG. However, I dunno if the taper of 7.62x39 links would work with the straighter Grendel case.

The only other option I see is to build a 6.5 upper similar to that of the 5.56 Colt "LMG" and put it on a full-auto lower. Not entirely satisfactory, to be sure, but perhaps it might be good enough to serve as a "test bed" of sorts? (This idea was discussed on the old forum, wherein Variable expressed an interest in trying it, but only if it could be done to his standards... )

[Tony Williams]

On the subject of barrier penetration, I found this interesting account:

Jason Gillis, a former Army staff sergeant, first witnessed the M855’s shortcomings in 2004 on the streets of Baghdad. He was a squad leader with 2nd Brigade Combat Team, 82nd Airborne Division, on patrol when a vehicle began speeding toward his unit.

After several warnings, “both of our M249s opened up instantly, forming a crisscross pattern of tracer that met at the vehicles engine compartment and windshield. Within seconds, riflemen and grenadiers were executing magazine changes while the vehicle kept rolling and finally stopped 10 meters from my lead troops,” Gillis recalled in an e-mail to Army Times. He is now a freelance writer who often focuses on military small-arms issues.

“Assuming the driver was most likely riddled beyond recognition, we were all astounded to see the driver emerge from the vehicle completely unscathed,” Gillis wrote. “Closer inspection revealed that the M855 ammunition had failed to effectively penetrate the vehicle’s windshield despite the fact over 400 rounds were expended at extremely close range and on target.”

I have read similar complaints about barrier (in general) and windscreen (in particular) penetration from a study of combat experience carried out by the Royal Marines last year (which included the SBS - their SEALS). This study showed that only about half of the Marines consulted felt that the 5.56mm ammo was "fit for purpose"; there was a majority view that an intermediate round could solve these problems; and that if that wasn't possible, they tended towards entirely replacing 5.56mm with 7.62mm. This wasn't just due to the longer range, but to greater effectiveness even at short ranges (they have a new 7.62mm rifle, the L129A1, and really like it).

[LR1955]

I have read similar complaints about barrier (in general) and windscreen (in particular) penetration from a study of combat experience carried out by the Royal Marines last year (which included the SBS - their SEALS). This study showed that only about half of the Marines consulted felt that the 5.56mm ammo was "fit for purpose"; there was a majority view that an intermediate round could solve these problems; and that if that wasn't possible, they tended towards entirely replacing 5.56mm with 7.62mm.

Tony:

And I would say well over 90% of this is anecdotal and pure opinion. Lets see the empirical studies.

A Soldier will always opt for what looks cool but when you run them through the simplest of evaluations you find that the chances of them actually hitting anything is small and gets smaller as the recoil and blast increases.

You will find that in most cases a Soldier will get the notion a cartridge sucks because he isn't hitting anything and blames the cartridge when he probably never even zeroed his carbine (happens more often than you may think) and otherwise is a lousy shot. Another one is that Soldiers will tend to believe that just because a cartridge is bigger such as 7.62 vs 5.56, that it must be better.

In the case of intermediate penetration and terminal effects, I tend towards scientifically run experiments more than a Joe's opinion. I have seen way too much over the years to trust the opinions of most (not all) military folks when it comes to small arms capabilities. There are some I do trust -- but most I don't.

Bottom line is that one has to prove a quantum leap in hit and kill probability before anyone will take a new cartridge seriously.

So, what would define a quantum leap in hit and kill probability?

LR1955

[Tony Williams]

And I would say well over 90% of this is anecdotal and pure opinion. Lets see the empirical studies.

I would say that there are three types of evidence which can be taken into account:

1. An accumulation of anecdotes from soldiers in combat (one by itself means little, if there are lots which are mostly saying the same thing, then it's worth paying attention). Given the immense burdens that they have to carry, I don't believe that soldiers would be willing carry the extra weight of 7.62mm guns and ammo (as they are, in both US and UK armies) unless they were satisfied that it was worth it.

2. Laboratory tests (there seems to be some sort of objection to testing ammo on live people, so substitutes like ballistic gel need to be used for comparison). Fackler and Roberts have both demonstrated the poor performance of 5.56mm.

3. The many attempts to improve the performance of 5.56mm, including MK262, MK318 SOST, M855A1 (and, of course, the 6.8mm Rem). If M855 were satisfactory, why bother to put in all this effort to improve on it?

Bottom line is that one has to prove a quantum leap in hit and kill probability before anyone will take a new cartridge seriously.

Not necessarily, if there are also other reasons for considering a change (e.g. to get a lighter round than 7.62mm, and to get one standard round, as I mentioned). And not at all if you're adopting a new technology like LSAT, where you're starting from scratch with all-new guns, ammo and production lines anyway. Then you might just as well go for the best solution, which as ARDEC recommended would be 6.5-7mm, and as JSSAP seems to have accepted in rejecting 5.56mm LSAT. But we can't expect the US Army to go for an intermediate LSAT unless the performance of the calibre has already been demonstrated in conventional form.

[noone]

Anecdotal reports are discounted in drug testing, and other types of testing because they are so often biased. The only truly useful data will come from actual testing in both field conditions, and lab conditions. These tests must use not only gell, but also actual tissue such as pig or goat carcasses. By combining both the lab, field, and carcass testing, we can get a reasonably accurate prediction of how a bullet will likely perform.

However, this kind of testing is very expensive, and time consuming. Unless a military is already looking for a new cartridge, or if someone is interested in selling a new cartridge, this testing is very unlikely to be done just out of simple curiosity.

This type of testing also gets us away from hit probability as a factor. It is presumed that the bullet will performed based on placement. Trying to predict a bullet's effectiveness based on the varying degree of marksmanship that the troops demonstrate, is sort of like predicting who will win the Indy 500 based on driver's skill, without considering vehicle performance...or like predicting the race based on vehicle performance without considering driver performance.

If we presume the same amount of marksmanship, or drivers skill, in either case, the bullet with better performance, and the vehicle with better performance will be superior.

[LR1955]

I would say that there are three types of evidence which can be taken into account:

Laboratory tests (there seems to be some sort of objection to testing ammo on live people, so substitutes like ballistic gel need to be used for comparison). Fackler and Roberts have both demonstrated the poor performance of 5.56mm.

The many attempts to improve the performance of 5.56mm, including MK262, MK318 SOST, M855A1 (and, of course, the 6.8mm Rem). If M855 were satisfactory, why bother to put in all this effort to improve on it?

Not necessarily, if there are also other reasons for considering a change (e.g. to get a lighter round than 7.62mm, and to get one standard round, as I mentioned). And not at all if you're adopting a new technology like LSAT, where you're starting from scratch with all-new guns, ammo and production lines anyway. Then you might just as well go for the best solution, which as ARDEC recommended would be 6.5-7mm, and as JSSAP seems to have accepted in rejecting 5.56mm LSAT. But we can't expect the US Army to go for an intermediate LSAT unless the performance of the calibre has already been demonstrated in conventional form.

Tony:

How about a citation for the Fackler and Roberts test, the ARDEC and the JSSP reports? If you can, include the page numbers.

You ask "If M855 were satisfactory, why bother to put in all this effort to improve on it?"

Show me were the issued M-855 failed to meet its requirements when it was tested and accepted in the early 1980's? You know that it did met the requirements set for it and that these requirements were based on ground war against the Soviets in Europe. The requirements changed, doctrine changed, training changed, and so we adapted.

And, instead of going through an immense RDTE process, we bought commercial bullets that had already been tested via the mechanism of capitalism. And, they work!

LR1955

[JASmith]

My wife did a master's in school nursing a few years back. My own experience and education has been in the technical arena where testing and statistics means verifiable, repeatable and quantitative measurement. Imagine my shock and dismay when I found that much of the statistics developed in education and the psychological arenas are derived from anecdotal reports.

Yes, it appears that appropriate controls and qualitative measures can be imposed on a body of anecdotal reports so that they generate actionable insight. Biggest challenge is eliminating bias from the assessment.

I remember reading the gun magazines and books of the '50s when the .17 caliber craze first got started. There were discussions of the effect of the tiny bullet on donkeys. For example, a chest hit resulted in "the blood coming out as a single organ." It sounded like we had found a magic pill and my younger brother even bought one.

A long time and a fair bit of experience later I will admit I'm biased in favor of a larger bullet -- and that that bias is largely due to having seen a whole host of anecdotal reports from both the hunting and the military world. I cannot say, however, that my own reading and study is an appropriate statistical analysis.

[LRRPF52]

That was my Brigade. If I think he is who I think he is, I went to basic training with the guy 10 years before that. It makes sense that we were the same rank, but he must have been in another Battalion. Anyway, it doesn't surprise me at all that his SAW gunners lit up the engine compartment of the car and had no connection with the driver. The M4 and 203 gunners could have been dumping mags in a mad minute at the car all day long, but since they probably were shooting from a kneeling position or standing position in the scenario described for the 1st or 2nd time in their lives, I wouldn't be surprised if they weren't getting any driver hits.

You have to realize that at that time, we almost exclusively did marksmanship training from the foxhole supported, or prone unsupported positions. In addition, we would conduct some really lacking CQM (Close Quarters Marksmanship) drills run by people who usually didn't know anything about CQM, unless they had been to SOT while they were back in Ranger Regiment. Even if we did have guys who were subject matter experts in CQM and CQB, the command climate in my battalion was so screwed up that the SME's (Subject Matter Experts) were rarely given the opportunity to cross-pollinate their knowledge and experience in formal training sessions.

Even with the CQM training that I received, being a gun guy, having been through much more marksmanship training in several Scout Sniper Platoons, I couldn't hit the kill zone on a man-size target at less than 75m from a kneeling position with my RAS-equipped M4 during live-fire MOUT exercises, and one of my former Ranger Regiment Team Leaders under me couldn't either. I want to blame the loss of zero or barrel flex associated with the RIS, or something else, but the sad reality is that we didn't ever run marksmanship training that duplicated those scenarios and shooting positions, and practical marksmanship is one of the most perishable skills.

I'm pretty sure we weren't connecting on target effectively because we had the wooden mannequins that were suspended in the houses with 550 gut (the white string within paracord) that was run through a 4" hole and tied to a balloon in the dummy's stomach, wearing BDU's. You lean the target slightly so that a lot of pressure is on the balloon in his or her chest area, so that when a projectile sails through, the target reacts by crumpling to the ground. I have seen instances where during freezing temps, the balloons just don't deflate since they are frozen in their blown-up size, but several more hits will make them collapse enough to slip through the hole and the target will drop at least some.

Another indicator that day in my/our lacking in CQM abilities was that I couldn't even hit a half silhouette target at maybe 15m while moving from the woodline to the first shoot house, and I was supposed to be the leader of my Squad. Reason: I had never trained on shooting moving targets like that with my M4, because we were doing parades, trash pick-up, area beautification, guard duty, and spending more time in starched BDU's and highly-polished jungle boots. I got into USPSA and 3-gun shortly thereafter, and I could make those hits now easily with my pistol, but you see where I'm going with this...

Now ask yourself how many of those Joes had ever shot at a moving target under stress ("You're gonna die if that vehicle gets close enough to you!!!) from alternate shooting positions with IBA on and sleep deprivation. I'll tell you: They probably never did. We occasionally did exercises in the 82nd where these levels of performance were demanded or expected of us, but we had never really done any formalized CQM training to support the building blocks that need to be in-place before we could produce any acceptable levels of individual and collective performance in them.

Another caliber with more recoil and less mag capacity might have gotten them killed in the above-mentioned scenario if the poor driver had actually had a VBIED. My understanding is that there have been some fundamental changes in marksmanship training, the leadership climate, and the underlying culture that created a lot of these problems, but I'm not sure about the 82nd. That unit had some serious leadership issues in the higher echelons that severely limited junior leaders in taking risks or conducting enough realistic training. If you talk to any E-5, E-6, or E-7 who wasn't raised in the 82nd, you'll hear the same thing. The Joes are fresh out of high school, so they are like clay ready to be molded. Most of them are hard-chargers who want to take names and are very patriotic. Some of the officers we had were great leaders who were the same, but most seemed more concerned about their personal careers, were risk-aversive, and were content upon hiding behind the whole airborne mentality that supposedly made us better than our light infantry counterparts in 10th Mountain, 101st, 25th ID, and the few light units in 2nd ID. My experience was that we trained to our METL (Mission Essential Task List) jobs in those light units way more than we did in the 82nd, but were Airborne, you see...

It really came down to the leadership climate at Brigade, Battalion, and Company levels. Some Battalions had a former SF Battalion Commander and a Sergeant Major from CAG. I can tell you right now that those guys trained like it was real around the clock, and had a great time and were quite lethal in OIF1. If you had a non-performer for a BC, a reject for a BN SGM, you were pretty much suckin' when it came to training, unless your Company Commander and 1SG were gifted at conducting good training under battalion's noses, which is not likely. (Try hiding 150 swingin' Joes from the BN weenies...)

You see how this is not a caliber issue though...

LRRPF52

[BluntForceTrauma]

Liberty Ammunition has a video addressing the 5.56 vs. windshield issue: http://www.libertyammunition.com/Lea...LIBERTY_T.html .

Of course, it's "sales and marketing" and not rigorous, unbiased testing, so take it for what it's worth.

I've seen a lot of dog and pony shows come and go. I think of how various gun makers heap mud or sand on their completely sealed AR and then pull the gun out of the mud or sand, shake it off, fire a few rounds, and we're supposed to be impressed that their weapon has passed some kind of extreme conditions test.

Glop mud or spray sand INTO the receiver and then we'll talk. . . . But I digress. . . .

John