How could or should the 6.5 mm Grendel be improved?

[Guardsman26]

As a professional defense industry consultant, I am involved in a project looking at future military ammunition types. I am not a ballistics expert, but as an ex-infantry platoon leader and company commander, I know something about how such products are used by the end customer!

Over the last 12 months several NATO armies have begun to look at the issue of caliber. The speed and ease with which the 8.59 mm cartridge has become a new and de facto NATO sniping calibre and, similarly, the way in which the 4.6 mm round has become a a de facto PDW standard has reassured military procurement personnel that maybe the barriers to caliber change are not so great.

For this reason, both the 6.8 mm Remington SPC and 6.5 mm Grendel have been evaluated quite extensively. To cut a long story short, the 6.8 mm Remington provides demonstrably superior terminal effectiveness to that of the M855 5.56 mm NATO round at all ranges to 400 metres. The problem is, however, that we need to engage targets at ranges of up to 600 metres in assault rifles (usually as a squad firing collectively), up to 800 metres for DMRs, and up to 1,200 metres for machine gunners with LMGs / SAWs. There is also the problem of Level III and Level IV body armour. Without extended range and power, the 6.8 mm SPC cartridge is not a valid substitute for 5.56 mm NATO.

Consequently, we have seen the wider re-introduction of 7.62 mm at squad level. Now that every UK infantry soldier is required to carry 200 rounds of belted 7.62 mm in addition to his own kit, we've all been reminded of the weight disadvantages of this larger calibre, not to mention the problem of training soldiers to shoot accurately with a rifle that has greater recoil.

Are we really stuck with 5.56 mm and 7.62 mm? It's starting to become obvious that the 5.56 mm M855A1 EPR is still most effective below 500 metres despite claims to the contrary. There are other concerns that I am sure everyone here is aware of, including massive costs. Meanwhile, 7.62 mm remains very inefficient, so loses energy rapidly. The thing is it works.

Against this backdrop the armies of several NATO members are looking at alternate calibers. Not surprisingly the 6.5 mm Grendel is starting to receive a lot of attention. (Kudos to you Bill A) it is certainly a highly respected solution and is now being evaluated widely. With all due respect to forum members own testing, a consensus opinion about the Grendel appears to be forming from within the military community. Let me underline the issues:

• The Grendel doesn't quite match 7.62 mm at 1,000 metres across all combat scenarios
  OTM bullets for precision target shooting are likely to provide better results than a lower standard military spec ammunition
  Concern about loss of energy when ammo fired from shorter barrels
  Concerns about high pressure loadings heating up weapons quickly in combat and possibly causing malfunctions
  Need to ensure the bullet design combines maximum efficiency with terminal effectiveness at all ranges
  

I have mentioned elsewhere that tests conducted by an EU manufacturer using piston AR15s showed marked energy reductions with weapons having barrels of 12" and 14.5" and 16" versus 24" and 20" barrels. Alas, I cannot cite my data sources. Apologies.

If we assume then that the Grendel, good as it is, is fine for target shooting and hunting, what could be done to make it a better military calibre? if anything.

The question I asked before remains valid: does it need a larger case to (a) give it more energy to compensate for shorter barrels (b) to ensure it is blind to yaw and blind to barrier © so that it matches 7.62 mm across all situations with a cartridge that is the same across all dimensions except for weight and recoil and (d) to compensate for generally lower standards of ammunition quality for military purposes?

Secondly, does the bullet need to be redesigned? Can anyone provide data on its lethality at short range?

This is open-ended research designed simply to gain perspectives from an expert user community. No one is suggesting that anyone's data is bogus, but military standards do differ from civilian ones. Similarly test methods also vary.

Feel free to PM me if you wish.

Thanks in anticipation.

[Trooper]

I would add a comment.

The 300 Blackout works better in short barrels than it does in longer barrels thus it is popular with the Spec Ops community for short barreled suppressed work.

For the average trooper, 16" barrels (ie M4 carbine) is short enough. For the DMR the 20" is common.

We know that the range of calibers is from 6.5mm to 7mm. That seems to be the sweet spot. The question then is what size diameter bullet has best BC/sectional density and so forth to put as much energy down range, especially at 700 to 1000 meters. Then the next question is what should the case size be? The Grendel seems to be limited to 43mm. Would 47mm be the better length? Is 51mm too long? Is case width needed to be about 10mm?

Trading all of these factors, what makes the best combination? And does keeping the M4 lower (which addes a design constraint), the current magazines, make sense? After all it does lower the cost of moving to a new caliber if one only has to add a new upper (barrel) rather than a whole new rifle, magazine and spare parts.

[Variable]

Hi Guardsman, My reply is below, and I hope it doesn't come across as confrontational, because I don't intend for it to be. I'm asking questions because they help me understand what you are wanting/expecting to get answers about.

As a professional defense industry consultant,To whom? I am involved in a project looking at future military ammunition types.For whom? I am not a ballistics expert, but as an ex-infantry platoon leader and company commander, I know something about how such products are used by the end customer!

Over the last 12 months several NATO armies have begun to look at the issue of caliber. The speed and ease with which the 8.59 mm cartridge has become a new and de facto NATO sniping calibre and, similarly, the way in which the 4.6 mm round has become a a de facto PDW standard has reassured military procurement personnel that maybe the barriers to caliber change are not so great.

For this reason, both the 6.8 mm Remington SPC and 6.5 mm Grendel have been evaluated quite extensively. To cut a long story short, the 6.8 mm Remington provides demonstrably superior terminal effectiveness to that of the M855 5.56 mm NATO round at all ranges to 400 metres. The problem is, however, that we need to engage targets at ranges of up to 600 metres in assault rifles (usually as a squad firing collectively), up to 800 metres for DMRs, and up to 1,200 metres for machine gunners with LMGs / SAWs. There is also the problem of Level III and Level IV body armour. Without extended range and power, the 6.8 mm SPC cartridge is not a valid substitute for 5.56 mm NATO.You already know the 6.5 Grendel is superior to the 6.8 for that role.

Consequently, we have seen the wider re-introduction of 7.62 mm at squad level. Now that every UK infantry soldier is required to carry 200 rounds of belted 7.62 mm in addition to his own kit, we've all been reminded of the weight disadvantages of this larger calibre, not to mention the problem of training soldiers to shoot accurately with a rifle that has greater recoil.Which is what we were trying to tell you-- weight and recol wise.LOL

Are we really stuck with 5.56 mm and 7.62 mm? It's starting to become obvious that the 5.56 mm M855A1 EPR is still most effective below 500 metres despite claims to the contrary. There are other concerns that I am sure everyone here is aware of, including massive costs. Meanwhile, 7.62 mm remains very inefficient, so loses energy rapidly. The thing is it works.

Against this backdrop the armies of several NATO members are looking at alternate calibers. Not surprisingly the 6.5 mm Grendel is starting to receive a lot of attention. (Kudos to you Bill A) it is certainly a highly respected solution and is now being evaluated widely. With all due respect to forum members own testing, a consensus opinion about the Grendel appears to be forming from within the military community. Let me underline the issues:

• The Grendel doesn't quite match 7.62 mm at 1,000 metres across all combat scenarios Agreed. The laws of physics must apply. There are no free lunches to be had, but the Grendel (In my opinion) hits the sweet spot exceedingly well. Factoring in size, weight, and recoil points squarely at the Grendel in my book.
  OTM bullets for precision target shooting are likely to provide better results than a lower standard military spec ammunition
  Concern about loss of energy when ammo fired from shorter barrels What load? At what length?
  Concerns about high pressure loadings heating up weapons quickly in combat and possibly causing malfunctionsCan you elaborate on that one? I have a registered sear, shoot full auto, and have had no problems.
  Need to ensure the bullet design combines maximum efficiency with terminal effectiveness at all ranges
  

I have mentioned elsewhere that tests conducted by an EU manufacturer using piston AR15s showed marked energy reductions with weapons having barrels of 12" and 14.5" and 16" versus 24" and 20" barrels. Alas, I cannot cite my data sources. Apologies.So: "Someone said they didn't like it, but I can't say who, or what the results were..."? We at least need numbers. We can only deal in facts and educated opinions.

If we assume then that the Grendel, good as it is, is fine for target shooting and hunting, what could be done to make it a better military calibre? if anything. A specifically designed projectile to help achieve whatever goal they are looking for (within reason, and they'd have to define that one), and dedicated powder for whatever envelope they wanted to shoot it out of.

The question I asked before remains valid: does it need a larger case to (a) give it more energy to compensate for shorter barrelsIn my personal opinion--- No. Again, what is the requirement? (b) to ensure it is blind to yaw and blind to barrier Blind to yaw? I'm a bit confused there. Are you saying you don't want it to tumble and fragment in flesh? If it's designed to be non-expanding, non-tumbling, and non-fragmenting... How do you expect it to have any real terminal performance? The 5.56 already does ice pick wounds in a smaller package at the longer ranges, unless you stack the deck to help it out. © so that it matches 7.62 mm across all situations with a cartridge that is the same across all dimensions except for weight and recoil and (d) to compensate for generally lower standards of ammunition quality for military purposes?That isn't possible. Again, no free lunches in the physics world. Mass and velocity equal recoil. The Grendel provides an excellent compromise, but it doesn't defy physics. It simply hits the sweet spot of being small enough and light enough while still giving you decent performance.

Secondly, does the bullet need to be redesigned? Can anyone provide data on its lethality at short range?Anecdotal real world observations-- It kills the hell out of whitetail deer and pigs. People aren't tougher. I know you really want statistical data, but so far there hasn't been a lot done (to my knowledge anyway). In the early days of the 6.5 vs. 6.8 wars the powers that be favored the 6.8, and did much more testing (with manufacturer support) on it than the 6.5 projectiles. Common sense will tell you that neither caliber is magic, and the 6.5 is simply better in it's designed format to deliver it's payload at range more efficiently. Lethality isn't just about energy, it's about how you expend it in the target. That primarily falls to bullet construction and can be optimized depending on what your requirements for it are (providing they are realistic).

This is open-ended research designed simply to gain perspectives from an expert user community. No one is suggesting that anyone's data is bogus, but military standards do differ from civilian ones. Similarly test methods also vary.

Feel free to PM me if you wish.

Thanks in anticipation.

[LRRPF52]

I started out wanting to slightly improve the cartridge, thinking about expanding case capacity, increase COL, ramp up pressure, etc., but I've come to realize that it is quite awesome the way it is, and it doesn't need a lot of tinkering really.

We tend to look at the requirements of fitting in the AR15 receiver set as a constraint, but it really is a blessing in disguise: For the dismounted infantry soldier, smaller, lighter, compact ammunition configurations go a long way, as you already know. One of the biggest suck factors of the 7.62 is that the projectiles are far away from the cartridge base, so they displace weight in pouches further away from the soldier, creating an offset weight distribution scheme in length and width.

As we keep the COL low, within the length of the 5.56mm, carrying capability becomes more user-friendly for the dismounts. If you narrowed it down to a certain projectile length/weight, you can play with the gas system length and optimize it for the bullet and load you're shooting to get the most velocity. For example, you will get more velocity with a 123gr from an 18" barrel with a rifle-length gas system, with the gas port cut for running that load well, but most of the production 18" barrels have mid-length gas systems so they will run the full gamut of projectile weights reliably, from 85gr-130gr. The lighter weight bullets need more dwell time to cycle the action fully.

The biggest challenge is in making links for the Grendel case, but I think an enlarged M27 link would work fine, with the feed pawls arranged to pull the neck and base.

The other thing to tackle is bolt geometry and the barrel extension if you wanted to increase the pressure. Currently, the system runs fine when kept at 50,000psi or under, and barrel accuracy life is longer than a 7.62 NATO. While seeking downrange performance from 400-800yds, you lean towards a projectile that doesn't do what 5.56 NATO does well within 125yds, namely fragmenting or rapidly expanding.

From the big picture logistics perspective, you have to convince bankrupt nations that the 11 years of logistical capacity they currently have needs to be replaced, and can be replaced while currently engaged in a high OPTEMPO posture, in multiple theaters of the globe. The .338 Lapua Magnum and HK mini mouse guns are employed in very niche sectors of the small arms spectrum, so that feeding them isn't as large a logistics challenge as replacing the main service rifle and LMG cartridge/system.

[Bill Alexander]

What is the optimum internal pressure for a small arms cartridges employing current generation smokeless propellant? This is the beginning of your quest. Here is a hint the Grendel is actually slightly low. It needs a nominal increase in internal pressure by remit of a slightly faster propellant or a heavy ball projectile.

Bullet construction should be matched to the hit probability (sigma x, sigma y) which dictates effective range and the target definition. (You do have a target definition of course? repeatable specified material and defined barriers to examine the performance requirement)

Now you need only balance recoil and controllability vs weapon weight and muzzle blast.

The final jigsaw piece is to then define the weapon durability. This is a real trick. Weight is directly proportional to durability which the influences the controllability.

WX6 at Fort Halstead used to call these weight performance spirals and looked at them in terms of carried kills. You are either going up or going down but to stay constant is near impossible.

So the dilemma that now sublimes is not so much how can you improve the Grendel, that is easy, but why should it be improved and to what specification. It is easy to say we need more but difficult to define why.

Here is a example of the puzzle. We have an AP that at the expense of range will pop through ESAPI at 100 yards. Equally we have heavy ball that will devastate glass, body armor and woodwork but the lethal arc is too short and carried kills drops.

[stanc]

The question I asked before remains valid: does it need a larger case to (a) give it more energy to compensate for shorter barrels (b) to ensure it is blind to yaw and blind to barrier © so that it matches 7.62 mm across all situations with a cartridge that is the same across all dimensions except for weight and recoil and (d) to compensate for generally lower standards of ammunition quality for military purposes?

a. That depends upon just how much energy is deemed necessary.
b. I think that is a function of bullet design, not case length.
c. If it is desired to match 7.62 performance, yes, a longer case is a must.
d. Probably so.

IMO, it will be necessary to lengthen the case by at least 4mm in order to design an M27-type link that will fit properly for interface with the feed mechanism, and allow sufficient shoulder area exposed for contact with the feed tray cartridge stop.

[LRRPF52]

c. If it is desired to match 7.62 performance, yes, a longer case is a must.

If you want to keep the peak pressure at 50,000psi, then maybe a slightly larger case or purpose-built industrial powder is needed to match 7.62 NATO velocity with a comparable BC projectile. The current Grendel case with a small rifle primer will exceed 7.62 performance quite easily if you want to ramp the pressure of the action up to be able to handle 58,000-60,000psi. The case itself will handle 62,000psi, but weapon longevity will suffer at the current configuration.

If I was in the UK, and had access to rapid-prototyping infrastructure, I would make several testbeds on the L85 and AR15 platforms, as well as the SCAR-16. The elongated longitudinal cam pin slot of the SCAR's bolt is central to its smooth recoil impulse, even though it has an off-bore axis reciprocating mass with the operating system. I would use an enlarged bolt head with beefed-up root area behind the lugs like on the .30 RAR, but use a standard-size AR15 carrier. It would be accompanied by an enlarged barrel extension, or one radiused like Knight's SR15E3 bolt and extension:



Do that, with a well-designed and manufactured extractor like the AA units, and you could run the pressures up with 123gr-130gr loads if you felt so inclined. A 130gr FMJ even will out-class even the Match 7.62 units in the 168-175gr class, when run at the same speeds, with much less recoil. You don't need to go crazy with the COL either. This would only be an appropriate DM Rifle and SASS (Semi-Auto Sniper System), as currently being filled with the L129A1 system, and would be much welcomed by the troops in those duty positions.

A 5.56 NATO will give you much better short-range performance, unless you had the assault rifle load in the Grendel with 85-95gr projectiles that would retain a substantial fragmentation range within close quarters, like the 85gr Sierra Hollow Point (non-land warfare compliant), or the 95gr AMAX (same). A 14.5" barrel M4 launching a 62gr NATO M855 is no freaking joke, especially at 2850-2920fps.

Here is an example of the recoil energy you will see with a highly-seasoned shooter with over 30 years behind rifles using a modern technique to mitigate the recoil and muzzle climb of a lightweight 16" Grendel with a 100gr polymer-tipped boat tail projectile on top of a stout load of Ramshot TAC powder, generating 2680-2700fps:

[video=youtube;qApXp7sH9QQ]http://www.youtube.com/watch?v=qApXp7sH9QQ[/video]
[video]http://youtu.be/qApXp7sH9QQ[/video]

That 100gr hunting load falls about halfway between 5.56 NATO and 7.62 NATO for downrange performance as to retained energy. A 108gr Lapua Scenar match-grade HPBT will very closely match 7.62 M118 trajectory and drift, but is a projectile that requires high standards of QC, and wouldn't be loaded into an assault rifle load.

[stanc]

Secondly, does the bullet need to be redesigned? Can anyone provide data on its lethality at short range?

I think it's incorrect to talk about redesign. Since no lead free military ball projectile currently exists, one would have to be newly designed. Actually, at least two such bullets would need to be developed:

- One acceptable to the US, probably constructed like M855A1.
- One acceptable to the rest of NATO, a non-fragmenting FMJ.

In addition, Eastern European armies might want a conventional steel-core ball round.

[LRRPF52]

There is a Barnes military projectile already for the Grendel, namely the 120gr TAC-TX:

Composed entirely of copper, these bullets have high weight retention and exhibit excellent performance when shot through barriers. Designed specifically for Military and Law Enforcement customers, these bullets function flawlessly in AR-type rifles.

Technical Information
Caliber: 264, 6.5mm
Bullet Diameter: .264"
Bullet Weight: 120 Grains
Bullet Length: 1.322"
Bullet Style: Tipped Boat Tail Lead-Free
Bullet Coating: Non-Coated

If it were me, I would still use lead, with a 7N10-type arrangement for the penetrator, with a thin jacket at the nose, that thickens at the base. It would have a concealed hollow nose.

[stanc]

There is a Barnes military projectile already for the Grendel, namely the 120gr TAC-TX:

Is the TAC-TX a general purpose ball projectile?

Is the TAC-TX (in any caliber) actually in military service, or is it just being marketed as a "military" bullet?

If it were me, I would still use lead, with a 7N10-type arrangement for the penetrator, with a thin jacket at the nose, that thickens at the base. It would have a concealed hollow nose.

The Russkis might go for that, but the lead content probably rules it out for the US and NATO.

[Variable]

but the lead content probably rules it out for the US and NATO.

Which tells me that they aren't actually too serious about real world performance in small arms. They are simply busy chasing their tails while jerking everybody around and wasting tax dollars, all while playing enviro-whacko and social engineering games. These politcally correct games coupled with all of our civillian side blunders (many intentional) will likely lead to a desperate need for actual performance sometime in the not too far future....

If the DOD (or other entity) issued real world performance requirements--- then a platform and cartridge could be aimed at filling those needs. Without those, it's just spitting in the wind.

[Guardsman26]

I think it's incorrect to talk about redesign. Since no lead free military ball projectile currently exists, one would have to be newly designed. Actually, at least two such bullets would need to be developed:

- One acceptable to the US, probably constructed like M855A1.
- One acceptable to the rest of NATO, a non-fragmenting FMJ.

In addition, Eastern European armies might want a conventional steel-core ball round.

Absolutely right. But the existing high BC 6.5 mm OTM bullet is an excellent start point.

The point about lead-free is not the absence of lead but its replacement with steel. This combines excellent barrier penetration with good terminal ballistics in soft tissue. Having seen the US Army ARDEC's research in this area, I need no convincing that lead free is the way to go, especially with body armour being used more widely by actual and potential enemies.

[LRRPF52]

The UK needs to work with the Scandinavian countries, Baltics, and Visegrad 4 to develop a new set of requirements if they are going to steer a new NATO or non-NATO standardization. As western world bankruptcy takes effect, I doubt any of us will find the least bit of support from the holders of the empty purses in Congress or Parliament, unless they see a get-rich quick scheme for themselves due to their district or personal ties to manufacturing that can be steered to financially benefit them.

One approach could be a challenge to a shoot-off of a new family of weapons between the US, the UK, the Scandinavians, the Germans, the Poles, and the Czechs. Everyone has been really infatuated with Stoner's AR-18 operating mechanism, with the Germans copying it with the G36 and XM8,



followed by Magpul with the Masada (now ACR),



The Belgian FN SCAR:



The Czechs and the Bren 805:




I've played with them all, except for the Radom. I like the weight of the SCAR, and the recoil impulse characteristics of the elongated longitudinal cam pin track of Stoner's AR-18 in all of them. The ACR is too heavy for what it is, and needs a diet. The Bren 805 seems like a copy of the SCAR with the receiver, and has good ergos.

I'd like to see a SCAR in 6.5 Grendel set up as a Sniper Support Rifle like they've done with the SCAR-17 7.62 NATO accurized variant for NSW Crane, as well as a DMR/SASS ACR variant in Grendel. The Poles and Czechs might also consider a Grendel demonstrator.

[LRRPF52]

The Poles with the Radom MSBS system:

[Trooper]

I would think that the goal of a GPC is "an ammunition that matches 7.62 mm NATO ballistics at 1,000 metres in a package that is 30% lighter. The 6.5 mm Grendel does this, but not as completely as we would like. Put a bit of extra power behind a slightly lighter projectile and you have a truly impressive round that is as lethal at 0 metres as it is at 1,000 metres. At least that is the theory." Thus it would work on the current M4/M16/L85 platform with either a barrel/bolt change or a new upper. But the majority of parts now in the rifle would not have to be changed out. Just a bit more powder so that it comes close to the power of the .260 Rem/6.5x55mm/6.5 BRM.

The basic Grendel cartridge is 6.5x38mm with a case dia of 10.6mm. This gives a magazine of 25 which is a good compromise between the 20 round 7.62 mags and the 30 round 5.56 mags.

I would hope that the specs include a G7 bullet rather than the G1 type. If manufacturers then produce high quality OTM match bullets (consumer market), the performance will be stellar for hunting and matches.

[stanc]

I would think that the goal of a GPC is "an ammunition that matches 7.62 mm NATO ballistics at 1,000 metres in a package that is 30% lighter. The 6.5 mm Grendel does this, but not as completely as we would like. Put a bit of extra power behind a slightly lighter projectile and you have a truly impressive round that is as lethal at 0 metres as it is at 1,000 metres.

That is extremely unlikely.

I would hope that the specs include a G7 bullet rather than the G1 type.

G1 and G7 do not refer to bullet type.

[bwaites]

G1 and G7 do not refer to bullet type.

Although this is correct technically, a G1 bullet type means a flat based bullet, while a G7 bullet type is a boat tailed bulllet.

[LRRPF52]

I would think that the goal of a GPC is "an ammunition that matches 7.62 mm NATO ballistics at 1,000 metres in a package that is 30% lighter. The 6.5 mm Grendel does this, but not as completely as we would like. Put a bit of extra power behind a slightly lighter projectile and you have a truly impressive round that is as lethal at 0 metres as it is at 1,000 metres. At least that is the theory."

As power goes up, so does recoil, taking us away from an assault rifle. The gun is controllable with a 100gr for close quarters, but still not like a 5.56 NATO, and won't be without some other changes. Pushing a 123-130gr closer to .260 Velocities takes us away from that, and we're not going to get .260 velocities, nor do we want them when weight/recoil is considered.

Thus it would work on the current M4/M16/L85 platform with either a barrel/bolt change or a new upper. But the majority of parts now in the rifle would not have to be changed out. Just a bit more powder so that it comes close to the power of the .260 Rem/6.5x55mm/6.5 BRM.

The basic Grendel cartridge is 6.5x38mm with a case dia of 10.6mm. This gives a magazine of 25 which is a good compromise between the 20 round 7.62 mags and the 30 round 5.56 mags.

A 25rd magazine capacity is a good change for the DMR and SASS, not any assault rifles. Trends in assault rifle magazines are going towards higher capacity than 30rd, not backwards.

My conclusions after mulling over this for most of my life are that approaching the small arms mix from the intent to fix assault rifles, is futile, because we have excellent assault rifles currently. We need to approach it from a big picture new generation of small arms, with fixing the SAW/LMG concept, and making a better DMR/SASS, while employing some other indirect assets lower in the organization. I see the Grendel as a great candidate for addressing the SASS and LMG, while displacing 7.62 NATO to vehicle-mounted only.

[Trooper]

As power goes up, so does recoil, taking us away from an assault rifle. The gun is controllable with a 100gr for close quarters, but still not like a 5.56 NATO, and won't be without some other changes. Pushing a 123-130gr closer to .260 Velocities takes us away from that, and we're not going to get .260 velocities, nor do we want them when weight/recoil is considered.




A 25rd magazine capacity is a good change for the DMR and SASS, not any assault rifles. Trends in assault rifle magazines are going towards higher capacity than 30rd, not backwards.

My conclusions after mulling over this for most of my life are that approaching the small arms mix from the intent to fix assault rifles, is futile, because we have excellent assault rifles currently. We need to approach it from a big picture new generation of small arms, with fixing the SAW/LMG concept, and making a better DMR/SASS, while employing some other indirect assets lower in the organization. I see the Grendel as a great candidate for addressing the SASS and LMG, while displacing 7.62 NATO to vehicle-mounted only.

The problem is logistics. We have too many systems in the mix. We need one caliber, one rifle, on machine gun. The same problem is there with the 20mm, 25mm and the 30mm. There they are planning to go to the 25mm round that is used on the Bradley's Bushmaster gun and on the F-35 and the Harrier.

[JASmith]

The problem is logistics. We have too many systems in the mix. We need one caliber, one rifle, on machine gun. The same problem is there with the 20mm, 25mm and the 30mm. There they are planning to go to the 25mm round that is used on the Bradley's Bushmaster gun and on the F-35 and the Harrier.

The 20mm cartridge is rather dated. I remember being part of discussions among us civil servants and military debating whether it made more sense to go with .50 caliber, 20mm, or to 30mm for aircraft cannon.

The argument for .50 cal was similar to that put forward by LRRPF52 -- you need lots of shots.

The argument for 30 mm was that one needs to tear up the opponent's aircraft.

20 mm won out because it was a balance and existed.

The 30mm GAU-8 was adopted because it could sneak through a few weak points in the Soviet T62 tank armor. It won because it as the smallest round that could do the job, never mind that it would take much to completely defeat it. Overlooked by most was the fact that that round makes mincemeat of everything else on the battlefield.

These arguments and the underlying assessments have been going on for an awful long time but I can draw one simple conclusion from them: The round that is adopted will be the smallest one capable of defeating the most heavily armored system in the requirements list.

The GAU-8 history suggests that the round might not be capable of defeating the best body armor, but that the number of hits more or less at random on the soldier so protected will find a spot where he will get hurt. This suggests that the conclusions drawn by LRRPF52 are reasonable with respect to the 5.56.

Similarly, the Grendel can match the 7.62X51 NATO standard round barrier defeat capability at ranges exceeding a few hundred meters. In close, both overmatch most targets of interest, so the GAU-8 lesson applies here too -- especially for dismounted infantry.

Mounted infantry enjoy a different set of constraints. One path to reducing the logistics burden might be to replace the 90+ year-old .50 caliber round with a more modern version in a smaller caliber. Newer technology would allow that round to exceed the .50 caliber performance at all ranges of significance.

The net result would be three cartridges in place of four: 5.56, Grendel in present form with suitable bullets, and the new heavy machine gun replacing mounted 7.62's and all applications where the .50 cal is used.