Grendel as a Universal Infantry Cartridge

[LRRPF52]

I just spent all day at the range with a bunch of AR's:

3 5.56 carbines
My 16" AA Grendel w/100gr Nosler BT's
My .260 Rem AR10
Some Sharps rifles in .45-70
M1A Scout 18"
Yugo SKS
A ton of other odds and ends... .22LR's, .44Mag pistols, Shotguns, etc.

I spent all the time with AR's, the M1A, and my .260. Recoil with the 16" Grendel was the same or maybe even less than the 5.56 guns. I was able to put rapid strings on-target at 7 yards the same as a 5.56 I think. I was shooting through a 1-4x GRSC, which is a little more difficult to shoot through than a red dot. I think a 100gr would make a great assault rifle load for a nation looking at upgrading their service rifles from 7.62x39, if they don't want 5.56 for some reason.

The M1A 18" Scout with break is a pussycat to shoot, as usual, but the break is somewhat punishing for those around you and in tight confines. It is very easy to make great shot placement with it though, for those who haven't shot one. The 18" M1A is my favorite of all the M14-type 7.62 rifles.

The .260 Rem is boringly accurate at 385m...no challenge for that caliber at that distance. It will group at 3 times that range.

[stanc]

I think a 100gr would make a great assault rifle load for a nation looking at upgrading their service rifles from 7.62x39...

By convenient coincidence the 5.45x39 steel-core bullet scaled up to 6.5mm would weigh ~100 grains, if I calculated correctly.

[LRRPF52]

Maybe the lower pressures with the Grendel equate to less felt-recoil with the 100gr projectiles, because the 120gr bullets definitely give you some increased felt recoil over a 5.56. The 100gr is a sweet spot as far as a lightweight carbine and felt recoil goes....first thing I noticed when I shot my 1st batch of 100gr NBT's...no muzzle climb or much recoil at all. Very pleasant to shoot.

[stanc]

120gr @ 2500 = 11% greater momentum than 100gr @ 2700.

Perhaps that's enough difference to be felt when shooting?

[LRRPF52]

Here;s the video comparison between 5.56 and the Grendel in similar configurations, and CQM shooting stances for close-range work:

5.56 14.5" (Phantom Permanently Attached for 16") BCM with Troy 13" Viking Tactics Handguard

6.5 Grendel with MGI QBC Gen I upper and Handguard Extension, 16" AA Barrel, 100gr NBT's on a stiff load of TAC

Back to 5.56 BCM

Maybe the 5.56 is a little more manageable. I need to throw the red dot on the Grendel and work with it some more, but an untrained soldier would have an easier time controlling the 5.56 I think. All shots were within the 7" plates.

[stanc]

Here;s the video comparison between 5.56 and the Grendel in similar configurations, and CQM shooting stances for close-range work:

Maybe the 5.56 is a little more manageable. I need to throw the red dot on the Grendel and work with it some more, but an untrained soldier would have an easier time controlling the 5.56 I think.

Those demonstrations show a noticeable difference between the two calibers. In the CQM drill, it took twice as long to fire 7 shots with 6.5 Grendel compared to 5.56 in the same exercise.

However, it was ~1 second for 5.56 vs ~2 seconds for 6.5 -- is that small amount of time likely to matter very much in combat?

P.S. First there was CQB, then came CQC, now there's a CQM? "B" is for Battle, and I think "C" is for Combat, but I haven't a clue as to what "M" stands for?

[LRRPF52]

Yeah, I need to work with the Grendel more doing rapid strings, which will take a fair amount of rounds. That was Lapua brass, so I ain't too eager to go spewing it all over tarnation.

CQB and CQC are the practical application of violence in closer engagement distances, from contact distance (muzzle to enemy chest or H2H) to maybe 75m. Close Quarter Marksmanship is the field of discipline at the individual task levels, including stance, low ready, high ready, shot placement and close range grouping drills, Mozambique drills, Bill drills, turns, alternate positions such as urban prone, barricade shooting, side prone, kneeling, transitions to sidearm, walking and shooting both forward and laterally, etc.

After a good amount of those exercises, you can start working shooters into 2-man teams with live-fire on a flat range, then 4 or more doing a ton of shooting around each other with movement, then start working into the houses. These would be your collective tasks under CQB, which are actually covered by the 8 Battle Drills in the Infantry Bible FM7-8, one section being Enter and Clear a Building, Enter and Clear a Room. There has been a lot of evolution in this area since the 1970's, to the point that is in urecognizable from then to now, just like the marksmanship techniques.

In any deliberate attack, Raid, Squad and Platoon Attack, and Ambushes, you actually use CQB when assaulting across the objective or kill zone, so while many think CQB is sexy stuff for urbanized areas only, it has broader applications for straight leg infantry units.

[stanc]

BTW, I was remiss in not expressing appreciation for posting those vids. While written descriptions and analyses are great, this is so much better as it enables us to actually see for ourselves the differences. Thanks!

[Tony Williams]

I just revamped my article on Future Infantry Small Arms, here (the changes are in red): http://www.quarry.nildram.co.uk/futu...all%20arms.htm

[stanc]

Tony,

Good article. Well reasoned. I especially liked the postscript, and the photo comparing 6.5 Grendel and 7 UIAC. I think that's the first time I've seen the two rounds together.

Clearly, a bullpup is the way to get a short rifle with maximized ballistic performance. However, until a bullpup is developed that successfully addresses the issues of ergonomics, ambidexterity, and adjustable length of pull, I'm not sure it should be advocated as part of the solution.

In light of the fact that such an optimized bullpup does not exist, combined with the longstanding antipathy toward bullpups in the US Army and the matter that the British Army has been put off them, might it be better to concentrate on pursuing a cartridge that can give the desired performance in a conventional carbine?

Stan

[LRRPF52]

Tony, I just read the article as well. The Grendel and 6.8 are much closer to 5.56 controllability, but not the same, however, I still think they are suitable assault rifle or carbine cartridges, although I prefer the 5.56 personally. The 7x46 UIC would be a bit too much for space utilization, weight, and recoil for the common assault rifle. It would make a great cartridge in the no man's land, but you simply can't mitigate the requirements for a close-in weapon and an LMG with the same loading. It is an interesting option for replacement of 7.62x51 in LMG's and maybe a DMR, but should not be considered for use in a carbine or standard service rifle.

As far as Mk12's and M14 EBR's being more and more popular, they are becoming less and less popular from what I understand, although MK12's are seeing more service with the USMC. Guys in Sniper duty positions are quite happy with a regular M4 with a drop-in match trigger and Mk.262, preferring that over an 18" SPR, since your job as a rifleman is more common than performing precision marksmanship functions at distance.

Also, from very reliable sources in the UK, I'm told that the 7.62 bolt guns have been binned in favor of the .338 LM AI's, which are mostly used in a static position in the defense, although there have been some rare exceptions with much fanfare. There is no reason to have a manual bolt operated 7.62 weapon, in my opinion, having carried them and suffering under their impracticality. They make great range queens, but have negative net effect in a maneuver war.

We could eliminate some of the logistics and over-diversification issue with a universal LMG, that fills the role of the SAW and the 240 without losing the 240's downrange effectiveness. 6.5mm can do that with the right projectile and loading. A friend of mine is getting 2700fps with 139gr Scenars out of a Cz527 bolt action, so an LMG with no requirement to baby brass could get significant velocity with a load heavier than 120gr easily. 6.5mm bullets will always out-gas 7mm from smaller cartridges. You need significantly more powder to make even a 6.8 VLD match a 6.6 for trajectory, and you still lose the wind deflection contest.

Even if we put a larger, heavier-recoiling rifle or carbine in Joe tentpeg's hands, it will not equal an increased hit probability passed the maximum effective range he can engage targets under stress from a hasty position while under fire. It will guarantee a logistics stress on his load, and less ability to recover shot-to-shot. There's no way around that which is practical.

We have to set some practical expectations that factor the soldier into the dismounted land component system from a holistic perspective, which the weapon is actually not much of a determining factor, in my opinion and experience. An extensive training and maturity curve in the mind and heart of a professional infantryman is what makes a difference in bringing about higher hit probability ballistic solutions with small arms, driven by an intensely focused trigger towards extreme violence to overwhelm an enemy.

It takes a lot of quality training to achieve that, which is almost impossible to achieve with a leadership climate that will never understand that dynamic until they have a demand for it downrange when it's too late.

Once the training solution code is cracked, guys who have stepped past it into a continuous cycle of maintaining proficiency love 5.56, and use it effectively from contact ranges out to 700m, some even making intentional 1st-round head shots as evidenced in one of the videos I linked previously, but the training cycle code has to be cracked first to make effective infantrymen, and practical marksmanship is just one individual skillset that comes together in a series of collective tasks that are necessary to make a unit effective in the dismounted game.

[stanc]

The 7x46 UIC would be a bit too much for space utilization, weight, and recoil for the common assault rifle.

It's no worse in that regard than the .280 British, which many still point to as what should've been adopted instead of 7.62 NATO.

...you simply can't mitigate the requirements for a close-in weapon and an LMG with the same loading.

The trouble with that idea is it is contradicted by history. During WWII the M1 Garand was used for close combat, and it fired the same loading as the M1919 LMG.

We could eliminate some of the logistics and over-diversification issue with a universal LMG, that fills the role of the SAW and the 240 without losing the 240's downrange effectiveness. 6.5mm can do that with the right projectile and loading. A friend of mine is getting 2700fps with 139gr Scenars out of a Cz527 bolt action, so an LMG with no requirement to baby brass could get significant velocity with a load heavier than 120gr easily. 6.5mm bullets will always out-gas 7mm from smaller cartridges. You need significantly more powder to make even a 6.8 VLD match a 6.6 for trajectory, and you still lose the wind deflection contest.

All that's true, but you're still thinking conventional, lead-core bullets. With "green" 6.5mm bullets, you're looking at a max weight of ~120gr, and projectile length that eats up a lot of powder space. To get an optimum length, a 6.5mm bullet is going to be only ~100gr. That may be too light to achieve the desired terminal effects, especially at long range.

If 120-140gr is needed to achieve the requisite performance on target, it'll probably be necessary to use 6.8mm or 7mm, even if trajectory and wind drift suffers to some extent.

[Tony Williams]

In light of the fact that such an optimized bullpup does not exist, combined with the longstanding antipathy toward bullpups in the US Army and the matter that the British Army has been put off them, might it be better to concentrate on pursuing a cartridge that can give the desired performance in a conventional carbine?

The problem with designing the cartridge to achieve a given performance from a 14" barrel is that it will need to be more powerful than one which achieves the same performance from a 20" barrel. So the cartridge will be bigger, heavier, recoil more and produce a lot much more muzzle flash and blast - which are all undesirable.

On the other hand, if you accept that you're only going to achieve the long-range performance you want from a 20 inch barrel so will only be able to use MGs and DMRs at long range then you can use the smaller cartridge, but the short-barrelled carbine will then be limited in its range performance. So you will still have two shoulder guns - a long-range rifle and a shorter-ranged carbine - instead of one general-purpose one, although the difference in their performance will be nowhere near as great as it currently is between 5.56mm carbines and 7.62mm rifles.

[stanc]

The problem with designing the cartridge to achieve a given performance from a 14" barrel is that it will need to be more powerful than one which achieves the same performance from a 20" barrel. So the cartridge will be bigger, heavier, recoil more and produce a lot much more muzzle flash and blast - which are all undesirable.

To be sure.

On the other hand, if you accept that you're only going to achieve the long-range performance you want from a 20 inch barrel so will only be able to use MGs and DMRs at long range then you can use the smaller cartridge, but the short-barrelled carbine will then be limited in its range performance. So you will still have two shoulder guns - a long-range rifle and a shorter-ranged carbine - instead of one general-purpose one, although the difference in their performance will be nowhere near as great as it currently is between 5.56mm carbines and 7.62mm rifles.

Must we accept that a 20" barrel is needed? Wasn't the L129A1 (which has a 16" barrel) adopted for the long-range requirement?

I'm thinking that it'd be possible to develop a long range cartridge better than 7.62 NATO for 16" barrel weapons. More importantly, it seems like it'd be far easier to get a 16" carbine adopted by the US Army than a 20" bullpup rifle. Maybe easier to get adopted by the British Army, too, if they've soured on bullpups.

[Tony Williams]

The Grendel and 6.8 are much closer to 5.56 controllability, but not the same, however, I still think they are suitable assault rifle or carbine cartridges, although I prefer the 5.56 personally. The 7x46 UIC would be a bit too much for space utilization, weight, and recoil for the common assault rifle. It would make a great cartridge in the no man's land, but you simply can't mitigate the requirements for a close-in weapon and an LMG with the same loading. It is an interesting option for replacement of 7.62x51 in LMG's and maybe a DMR, but should not be considered for use in a carbine or standard service rifle.

Don't forget that the recent ARDEC calibre tests, which were aimed at assessing the optimum cartridge for a new carbine not a general-purpose round, took into account recoil and ammunition weight in reaching their conclusions that the optimum calibre using the latest service-type bullets is between 6.5mm and 7mm (although there is some inconsistency in the figures which raises doubt as whether these are bore or bullet diameters - if the latter, the optimum bore calibre would be 6.35-6.8mm). Furthermore, I have heard that the loadings they tested in these calibres were fairly "hot" - more than a Grendel, for instance.

As far as Mk12's and M14 EBR's being more and more popular, they are becoming less and less popular from what I understand, although MK12's are seeing more service with the USMC. Guys in Sniper duty positions are quite happy with a regular M4 with a drop-in match trigger and Mk.262, preferring that over an 18" SPR, since your job as a rifleman is more common than performing precision marksmanship functions at distance.

I didn't comment on MK12 popularity, merely noted it as yet another gun in service. I expect that the popularity of 7.62mm heavy rifles will vary depending on the circumstances - if many of the engagements are at long range they become extremely popular, but if the job is mostly house-clearing then a 5.56mm carbine clearly has appeal.

Certainly all of the feedback I've had about the L129A1 in British service is highly positive. I am also told that the Royal Marines (who ran a detailed study on the calibre question, including consultations with troops) would prefer an intermediate round but, faced with the choice between 5.56mm and 7.62mm, most of the combat-experienced troops would drop 5.56mm altogether and go back to 7.62mm for everything.

Also, from very reliable sources in the UK, I'm told that the 7.62 bolt guns have been binned in favor of the .338 LM AI's, which are mostly used in a static position in the defense, although there have been some rare exceptions with much fanfare. There is no reason to have a manual bolt operated 7.62 weapon, in my opinion, having carried them and suffering under their impracticality. They make great range queens, but have negative net effect in a maneuver war.

Yes, the BA's 7.62mm L96 bolt-action sniper rifles have all been replaced by .338 L115 because of its much superior long-range performance. The US Army is of course doing something similar with its bolt guns, rebarrelling them from 7.62mm to .300 Win Mag, for the same reason.

I wasn't suggesting that carrying 7.62mm bolt guns on patrol was a good idea - it was only done in the BA because they were desperate for something with a better long-range performance than 5.56mm, and the L96 was all they had to hand. I am told that when on foot patrol in areas where the engagagement distances are likely to be long, it is not unusual for an L115-armed sniper to accompany the patrol. This is not of course the way in which snipers are normally used, but it indicates the importance given to effective long-range small-arms fire.

We could eliminate some of the logistics and over-diversification issue with a universal LMG, that fills the role of the SAW and the 240 without losing the 240's downrange effectiveness. 6.5mm can do that with the right projectile and loading. A friend of mine is getting 2700fps with 139gr Scenars out of a Cz527 bolt action, so an LMG with no requirement to baby brass could get significant velocity with a load heavier than 120gr easily. 6.5mm bullets will always out-gas 7mm from smaller cartridges. You need significantly more powder to make even a 6.8 VLD match a 6.6 for trajectory, and you still lose the wind deflection contest.

A couple of years ago I would have agreed with you but, as Stan points out, it's the lead-free ammo requirement which changes the traditional equations. I really don't know what the optimum calibre will turn out to be, it is very dependent on just how aerodynamic the bullet shape can be made for mass production.

Even if we put a larger, heavier-recoiling rifle or carbine in Joe tentpeg's hands, it will not equal an increased hit probability passed the maximum effective range he can engage targets under stress from a hasty position while under fire. It will guarantee a logistics stress on his load, and less ability to recover shot-to-shot. There's no way around that which is practical.

We have to set some practical expectations that factor the soldier into the dismounted land component system from a holistic perspective, which the weapon is actually not much of a determining factor, in my opinion and experience. An extensive training and maturity curve in the mind and heart of a professional infantryman is what makes a difference in bringing about higher hit probability ballistic solutions with small arms, driven by an intensely focused trigger towards extreme violence to overwhelm an enemy.

It takes a lot of quality training to achieve that, which is almost impossible to achieve with a leadership climate that will never understand that dynamic until they have a demand for it downrange when it's too late.

Once the training solution code is cracked, guys who have stepped past it into a continuous cycle of maintaining proficiency love 5.56, and use it effectively from contact ranges out to 700m, some even making intentional 1st-round head shots as evidenced in one of the videos I linked previously, but the training cycle code has to be cracked first to make effective infantrymen, and practical marksmanship is just one individual skillset that comes together in a series of collective tasks that are necessary to make a unit effective in the dismounted game.

All good points and I entirely agree that training is by far the most important element in soldier performance, and that not enough training in long-range marksmanship has been provided in the past (although I understand that this has changed recently).

I am only interested in seeing that the soldiers get a gun+ammo combo which meets their needs and overmatches whatever the likely enemy has. The view from just about every UK and US military source I've heard is that 400m is the maximum range for effective 5.56mm fire - maybe 500m if you really push it, but then you can run into serious wind-drift problems - and that the standard infantry rifle needs to shoot further than this in the future (something which becomes feasible with the new sights coming down the track).

The most favourable comment I've heard about 5.56mm is that it's tolerable within its range limitations as long as it's backed up by 7.62mm weapons for longer range fire. Which takes us right back to the situation I started my article with!