Requirements for Replacement of Currently Issued 5.56 M-855 and 7.62 M-80.

[LRRPF52]

Gents,

I'm in favor of a 3-caliber (really 5+) system for shoulder-fired weapons for dismounted infantry soldiers:

Caliber 1: Riflemen should have an improved M4 carbine (including the British-just look at what SAS and SBS carry and you won't see L85A2's) with a cartridge that does not weigh more than 5.56 NATO, does not sacrifice 5.56 NATO mag height for capacity, and can push a 55gr projectile at 3,050 fps, or a 62gr at 2,950 fps like the M4. If this could be accomplished with the 6x35mm KAC PDW cartridge from a 14.5" pipe, that would increase the load-carrying capability of my riflemen. Remember, riflemen will also be tasked to carry at least a 100rd belt of 7.62 NATO or 200rd drum of SAW or equivalent weight of linked ammo for the machineguns in their squad or platoon. When it comes time to kick in doors or fight in enclosed spaces, including streets & alleys, you don't want to be slugging it out with anything that resembles the muzzle blast of an AK or 7.62 battle rifles, and you don't want anything longer than a 16" pipe.

Caliber 2: The Multi-Role Light Machinegun Cartridge, which would be common with the Semi-Auto Sniper System (SASS) cartridge. As long as it weighs less than 7.62 NATO and not too much more than linked 5.56, & delivers 100m more 1st-round hit probability, we would have something. I think a 6.5 to 7mm diameter range would be the ticket here. Maybe something like a 6.5x47 Lapua or 7x47 Lapua, but a 6.5x47 would be a throat burner without some serious developments in propellant and or barrel metallurgy. This would replace linked 5.56 NATO, linked 7.62 NATO, and also be available in a match round for the SASS to replace M118 and M852.

Caliber 3: Long-Range Interdiction cartridge in .338 LM. This would be for snipers and DM's in the anti-material role, and would negate the limited use of .300WM in some units, while offering much of what the Barrett does to conventional units. The Brits and about every other NATO country are on-board with .338 LM anyway. There are currently-available API and HE projectiles for .338 LM as well, and the rifle chassis for .338 LM is not much more than an M24 in weight, while doubling the effective range of that weapon. With some of the developments going on with .338 LM right now, it is basically transitioning from a 1600m to 2000m effective range weapon, when using the solids out of 30" barrels. An auto-loader .338 LM would make a 29lb M107 less and less desirable as well.

In summary, only one new caliber could be introduced while phasing out 7.62 NATO, and that would be the new MRLMG/SASS cartridge. It would mean that an Infantry rifle squad would now have 2 LMG's capable of area target suppression at 1000m and beyond (7.62 is book-defined out to 1800m for area suppression), with a man-size hit probability per 1st controlled burst closer to 700m. It would also have the capacity to field 2-4 SASS rifles in the same caliber with match ammo that is lighter than 7.62, and has an increased 1st-round hit probability past 600m, that also is easier to fight with in closer ranges due to less muzzle blast and recoil.

That would leave a 9-man Squad with the Sqd LDR carrying either an M4A2 or a SASS, 2 LMG gunners, 2 M4A2 w/40mm Grenade Launchers or the new XM29, 1-2 DM's with the SASS, and 2-3 Riflemen with M4A2's. It is essential that the LMG actually be lightweight, as in 10 lbs or less, with constant recoil operating principle. As we have been encountering with the M14's and M110's, there will be more rifles assigned per squad than soldiers, leaving the unit with the flexibility to configure its soldiers for the Area Of Responsibility/Mission/etc. Another advantage to this is that current SASS rifles could be re-barreled easily when they hit their barrel wear, and the Brits don't even need to send off their L129A1's since it is an LMT Monolithic Upper Receiver with the ability of the user to change barrels with a torque wrench.

Brits/UK
With the L129A1 system, when operating in an urban environment, a 16" lightweight barrel could be installed by Joe during mission prep, and he would still be good-to-go for kicking in doors with a lighter load using a thin jacket. A 100gr 6.5 projectile out of a x47 case capacity would scream, even out of the 16" pipe, and could devastate at close range. That would also be a great 300-400 bullet in the city.

Remember, there will almost always be more than 3 types of ammunition used, even if you go to a one-caliber system, since linked ammo and magazine ammo will be issued and used in their own exclusive systems anyway, and you still have several types of Grenade Launcher rounds. The introduction of the XM29 will add a new caliber to the system, and most likely ensure the retention of 5.56 NATO or something smaller if they stick with the PDW/Burst Munition Launcher combo. The 6x35 PDW would actually work better in that system since it was purpose-built for a short-barreled AR carbine, which is exactly what the OICW has. If we could get the 6x35 to shoot it's 65gr projectiles at 2900fps out of a 14.5" or 16" barrel, that would be nice, and could initiate the replacement for 5.56 NATO. It would also open the door for a 6mm SPR in the AR platform, but mag length issues would need to be balanced between the assault rifle load and the DM load. From an end-user perspective, this is what seems to make the most sense to me, and the field is actually ripening for these moves if the XM29 gets adopted.

LRRPF52

[RedFalconBill]

If we could get the 6x35 to shoot it's 65gr projectiles at 2900fps out of a 14.5" or 16" barrel, that would be nice, and could initiate the replacement for 5.56 NATO.

There is no way for the 6x35 (aka 6mm Whisper and 6mm-221 Fireball) can get those types of velocities. You would need the 6x45 and an 18", or longer, barrel. Since the 65gr 0.243" bullet has the same SD as a 55gr 0.224" bullet, just how much better will a 65gr 0.243" bullet @ 2,900 fps be than a 55gr 0.224" bullet @3,200fps?

I also have not chrono'ed many M-855 rounds, that when fired out of an M-4, go much faster than 2,900 fps, let alone 2,950 fps. The bulk of the ammo has averaged 2,890 fps +/- 30 fps.

[LRRPF52]

Yes, XM29 was cancelled. I was thinking of it since one of the Scouts in my Brigade in 25th ID died testing it in 1998-99 when the programmable munition detonated while he was aiming it. The new one is the XM25 without the PDW component.

M193 (55gr) out of an M4 with 1/7 twist is listed as 3050 fps, while 62gr M855 is 2920 fps. I'm sure some variances would put the ES to possibly 50 or 70 fps less, but it is still a hot load with brutal wound ballistics within 100m, and very difficult to match within the size constraints.

I just don't think a new LMG should be limited by AR magwell dimensions, since it won't and shouldn't matter if the LMG uses linked ammunition anyway. It also shouldn't be limited by 7.62 NATO weight penalties since we can exceed M80 ballistics with lighter projectiles.

I would leave 5.56 NATO alone, other than making Mk262 more available to DM's, and upgrade the M4 to a rifle-length float tube and quick-barrel change system possibly. The 3-round burst mechanism should be replaced with the original AUTO mechanism, so the pull weight is no longer affected by that horrible burst counter wheel and the additional disconnector. The real area of focus should be on making a lightweight LMG that exceeds 7.62 ballistics, and can be wielded in Close-Quarters as well. That pretty much forces us in the direction of a Bullpup LMG design, which is hard to belt-feed, but I have some ideas.

LRRPF52

[LRRPF52]

I lean towards keeping the belt-feed system for machineguns since we can replace both the SAW and the M240 with one weapon, that will exceed 240/7.62 capabilities from a platform that weighs almost 1/3 the 240B (27.6lbs). Having humped both the SAW and the 240 and managed them from a Rifle & Weapon's Squad Leader duty position, I lean heavily towards a belt-fed machinegun over a mag-fed Automatic rifle any day, especially if the LMG can weigh about 10 pounds, which has already been accomplished with several designs. The KAC LMG, Shrike, and Stoner 63 are all examples of very lightweight belt-fed LMG's.

We have to balance out the weights and weapon profiles that every Joe carries, and I argue in favor of moving the current imbalance of the SAWs and 240's towards the profile and weight of the M4. If we do that and increase our ballistic potential (both totally feasible), we have made leaps and bounds in the structuring and mobility of dismounted Infantry.

LRRPF52

[JASmith]

Gents,

I'm in favor of a 3-caliber (really 5+) system for shoulder-fired weapons for dismounted infantry soldiers...

This looks like an excellent start for a thread discussing systems that fill the need being defined in this thread.

Doing so would help keep focus on each thread topic.

Any of us can do it. Probably the simplest way is to quote LRRPF52's 3-cartridge discussion along with a prefatory comment and away we go!

Cheers!

[stanc]

The real area of focus should be on making a lightweight LMG that exceeds 7.62 ballistics, and can be wielded in Close-Quarters as well. That pretty much forces us in the direction of a Bullpup LMG design, which is hard to belt-feed, but I have some ideas.

I dunno if a bullpup is feasible, but a semi-bullpup GPMG can be done. Actually, such a design already exists.

http://www.youtube.com/watch?v=48pFvx4hlbo

http://www.youtube.com/watch?v=m3T3DY2fR6w

[LRRPF52]

Roger...M60 and FG42 before it are considered "half-bullpups", but I'm thinking of a true bullpup, belt-fed LMG that weighs 10lbs or less. I grew up on the M60 and was kinda surprised when we replaced it with an older design...the MAG58 with the US Nomenclature of M240. The MAG58 runs much more reliably since it has a solid feed tray cover and a long-stroke piston, but the M60 was a much smaller profile to carry, and had what very few GPMG's have-a forward handguard. I do like the M60's quick barrel change latch better than any other. They carried that over to the SAW as well.

LRRPF52

[Tony Williams]

I'm in favor of a 3-caliber (really 5+) system for shoulder-fired weapons for dismounted infantry soldiers:

I don't doubt that your proposals would have advantages over what we have now, although the limited propellant capacity of the 6x35 seems likely to restrict it to a 200m (maybe 300m at the very most) effective range. So it may be necessary to carry more of a balanced mix of carbines and DMRs unless the fighting is all in towns. I agree with you over the .338, by the way, but regard that as being in a separate category.

As a result of my experience in debating these issues with MoD in the UK, I think that the problem which any replacements for just the 5.56mm, or just the 7.62mm, will face is this: yes, you can produce ammo which has advantages over the existing calibres - but the advantages are not so great that they justify the huge disruption and cost of the change.

In my opinion, this is where the single-calibre solution can deliver a more compelling argument in its favour - provided that a satisfactory performance can be achieved. By replacing both 5.56mm and 7.62mm with one general-purpose round, you achieve not just one improvement but "three for the cost of one": lighter weight and recoil than 7.62mm, better range and effectiveness than 5.56mm, plus the various cost and flexibility advantages of having only one round and weapons family rather than two to procure, support, train and fight with.

I would be surprised if the XM29 makes a come-back. It was concern over the effectiveness of the 20mm grenade which caused the increase to 25mm in the XM25, which meant that the 5.56mm element had to go - the weight of the XM29 was already too much, and would have increased still further in 25mm.

As a matter of interest, I spell out my thoughts on the subject of a near-future small arms system here: http://www.quarry.nildram.co.uk/futu...all%20arms.htm

[JASmith]

A follow-up thought - given the likely weight of the DMR and the reduced recoil of our general-purpose cartridge, it could also be given selective fire to act as an automatic rifle.

Sort of like a 21st Century BAR!

I had overlooked this comment earlier but just ran across it while reviewing for an update on the requirements descriptions.

A selectable fire DMR rifle with the ability to use the same ammunition as the rest of the squad is truly a neat idea. Had to think about it but I now realize that this would likely give the DMR better capability when things get close.

I wonder how this would mesh with the experiences Gene and LRRPF52 have?

[LRRPF52]

Re: DMR's as multi-role BAR's or LMG's, the Marine's approach to the Auto-Rifleman concept has kind of re-introduced that with the M16-based Automatic Rifle that fires from the open-bolt, but uses a push-rod system to handle the increased heat of frequent automatic fire. As I said, the success of that system will rest heavily upon the reliability of the new coffin mags from Surefire and Magpul, which I have yet to hear unbiased extensive field reports of. I can already tell you that the CMAG fails when the slightest amount of dust is introduced to it, as we were issued a few before deploying to OIF1. Unfortunately, they don't work in field conditions.

To me, a Light Machinegun is all about sustained firepower without the gunner having to reload frequently, and the only systems that do that really are belt-fed, followed by some exceptions with drum-fed. The biggest problems with drum-fed mags is the time it takes to load them plus the carry issues with them for pouches, whereas linked ammo just keeps flowing through the logistics chain and can be fed right into the guns without any extra procedures if need be. It is also much easier to feed linked ammo into the soft bag "nutsacks" we used for the SAW, which several after-market companies run by SF and grunts have mimicked for the M240 and even PKM.

The Finns had a lot of success with the Kp31 9mm SMG using 72rd drum mags, but loading the mags to meet the target-rich environment was problematic for them, to the point that they ran the Kp31 in static positions with an "Assistant Gunner" loading drums for the shooter. They even came up with a plastic loading tool for the drums after the war to have ammo pre-positioned so it would slap right in, versus the tedious task of hand-loading each round. Imagine doing that in -20 and -30 C weather and that's what they did.

A new LMG could incorporate a select-fire mechanism, even with a select bolt-open or bolt-closed operating mech as is currently available with the M16-based LMG's. As you look at what new aiming and targeting systems are being introduced in the future force concepts after Land Warrior and such, this idea might make more sense for an LMG that can also deliver single rounds in a precision mode if needed. If it can be done reliably, without causing more problems with all the small parts, I'm all for it.

LRRPF52

[LRRPF52]

As a result of my experience in debating these issues with MoD in the UK, I think that the problem which any replacements for just the 5.56mm, or just the 7.62mm, will face is this: yes, you can produce ammo which has advantages over the existing calibres - but the advantages are not so great that they justify the huge disruption and cost of the change.

In my opinion, this is where the single-calibre solution can deliver a more compelling argument in its favour - provided that a satisfactory performance can be achieved. By replacing both 5.56mm and 7.62mm with one general-purpose round, you achieve not just one improvement but "three for the cost of one": lighter weight and recoil than 7.62mm, better range and effectiveness than 5.56mm, plus the various cost and flexibility advantages of having only one round and weapons family rather than two to procure, support, train and fight with.

The biggest obstacles to a one-caliber system are the varying performance requirements for a combined arms team. What I want a bullet to do in the house, forest, and city streets from my carbine with riflemen is almost opposite of what I want it to do from my LMG's at 200-900m. The weight penalties to favor an LMG performance envelope prohibit the close-in fight envelope from a practical standpoint. I think of assault rifles/carbines as over-powered submachineguns with the capability to reach out to 300-450m depending on the cartridge, which is really an awesome achievement in the history of warfare. For the majority of practical engagements that a rifleman will use his weapon in, it's hard to find anything better than 5.56 NATO.

I would not pay too much attention to articles that start out with the premise, "Everyone knows the 5.56 is an anemic man-stopper." or, "Soldiers have been complaining since Vietnam about the ineffectiveness of 5.56..." Soldiers have been complaining about everything since the beginning of time, and professional career soldiers in special operations units around the world who have a lot of leeway in which weapons they can use seem to mysteriously choose the M4A1 or Diemaco equivalent, including your SAS & SBS, Aussie SAS, Danish, Norwegian, Israeli Light Infantry & CT units, let alone SOCOM and JSOC. What is it that these guys know-many of whom come from Light Infantry units with real world tours before they go through the selection and training process for those types of units? My position on 5.56 NATO is that it ain't broke, it's plentifully available, and it often blows living tissue apart where it hits within 100m.

Machineguns need to be able to reach out from that point onwards, and Squad/Platoon-level LMG's need to support the fight in urban areas as well. This requires an entirely different animal with regards to trajectory, penetration, feeding systems, etc. To me, it is counter-productive to try to get these two realms to jive together, although the Grendel does seem to be the best compromise I can think of, but I feel sacrifices too much edge off of each to be worth pursuing in that regard, especially since the assault rifle realm is not broken, and the machinegun realm has lots of room to improve in to make a leaner, more lethal fighting force.

While we recognize that it will likely take something revolutionary to replace anything within the current system, replacements are going to inevitably happen at some time, which is why it's important to keep a healthy debate, testing atmosphere, and brain-storming session alive. I thank you all for that, by the way.

LRRPF52

[stanc]

The biggest obstacles to a one-caliber system are the varying performance requirements for a combined arms team. What I want a bullet to do in the house, forest, and city streets from my carbine with riflemen is almost opposite of what I want it to do from my LMG's at 200-900m. The weight penalties to favor an LMG performance envelope prohibit the close-in fight envelope from a practical standpoint.

Granted, the one-caliber approach is not ideal for close combat, but it was used quite successfully for that purpose by US infantrymen in WWII and Korea. And they used a rifle which was nearly four feet long, too!

To say that CQB is only practical with a short-barrel, telescoping-stock carbine and minimum-size cartridge is contradicted by history.

[JASmith]

To say that CQB is only practical with a short-barrel, telescoping-stock carbine and minimum-size cartridge is contradicted by history.

True -- "only practical" is a strong statement in the light of history. One could also note that lessons of history suggest that a shorter weapon with adequate lethality makes the whole chore easier and more efficient...

The points made by Tony and by LRRPF52, in my view, nicely span sensible options. Both have excellent logic and factual support. So, I feel confident that our explorations will result in interesting options to bring into play when the opportunity presents...

[LRRPF52]

Tony,

The Garand was only one weapon in the mix of Thompsons, BAR's, M1 Carbines, and Browning M1919 machineguns...supported by tanks often. Also, the US forces in the European theater entered WWII pretty late in the game, and only faced about 1/3rd of the Wehrmacht, and those forces were often the newly-recruited, recovering injured, youths, and generally ones who weren't fit to be on the Russian front-where the most intense Eurasian infantry battles were fought. Those fronts also were priority for fielding of the Stg44, elite German units, and the main strategic focus of Germany.

Furthermore, they weren't fighting opponents with AKM's and PKM's, so while WWII introduced the paradigm shift of the Assault Rifle, its lessons were largely lost in the US ordnance circles responsible for small arms development, which was painfully evident with the adoption of the single-caliber system with the M14/M60 and the 7.62x51 cartridge. England had a much more viable cartridge at the time in many respected military professionals' opinion, and that was of course the .280 Enfield. The US dominance in systems standardization in NATO basically screwed England, Belgium, Germany, Denmark, Norway, and other countries into adopting the 7.62 NATO as a standard service rifle cartridge, which then became the chambering for the FAL/G1, CETME & later G3, and the other ancillary "Battle Rifles" under the West's influence, which was a shame really, and that's coming from a Yank.

The only redeeming thing for service rifles to come along was the AR15 in 5.56x45, which the US of course switched to quite rapidly after the blatant inadequacy of the M14 in maneuver warfare. Also keep in mind that much of the rice-filled plains in Vietnam provide excellent fields of fire at ranges that would challenge even long range calibers, so it isn't a 100% saturated triple-canopy environment as many would like to brush with one stroke. The AR15 had already become a favorite of the British SAS in Malaysia before major US troop involvement in Vietnam, and continues to be a mainstay as the go-to platform for a small, shoulder-fired weapon for utility across most operational mission profiles in that unit.

I can't tell you enough what a heaven-send it was when we received M4 carbines in conventional and recon units in the US Army. I had been a big proponent of equipping key leaders, RTO's, AG's, FO's, medics, and Scouts with the M4 carbine as I had seen it fielded with 18th Abn Corps LRSC, but knew it would never happen because it made too much sense. Imagine my surprise when I saw our Company Commander walking with one in hand telling my Scout Platoon Leader and First Sergeant about it, and then seeing our entire arms room filled with them! That was one of the best days of mine in the Army, and I was even more surprised when all the M16A2's were replaced with the M4 in Light Infantry, Airmobile, and Airborne units.

Even in the dominant open terrain environments in a high desert mountainous region, small unit tactics in the US system involve a lot of different duty positions that I briefly mentioned-all of which would be ill-suited with a larger caliber rifle with a bigger weight and length profile. The M4 is about perfect for them, since my Medics, Forward Observers, Assistant Machine-Gunners, Ammo-Bearers, Radio Operators, and most Key Leaders will not be even attempting to make hits on individual targets past 50m, let alone 100-300m. We haven't even addressed the Mortar Platoon, Scout Platoon, Company & BN HQ, etc. What rifle would they end up with in a single-caliber system?

Now think about a Leader's recon, which is always conducted before deliberate attacks, ambushes, and raids (which are the 3 types of planned missions or combat patrols dismounted units engage in). During a recon, your job is to move into an area, gather the battlefield info you need, and get back to your unit while remaining undetected the entire time of course. This requires as low a profile as possible, and the M4 fully-supports that role. If chance contact is made, the unit breaks contact using fire & maneuver to get out of the effective range of the enemy as quickly as possible, which usually involves a lot of ammunition being expelled to make the enemy think they have hit a larger force. The most helpful thing in that scenario would be a mix of M4's and a comparable-weight LMG with a short profile that could pump out a lot of firepower, like the Peruvians have with the Ultimax LMG.

Does this shed a little more light on why a single-caliber system doesn't make sense? Remember that there are a lot of guys who compliment the dismounted fighting force with weapons that bring more firepower to bear than anything hand-held, that being the RTO's, TAC-P's, and FO's linked to indirect fire & CAS assets. They are organic and attached personnel (TAC-P's & FO's) as a rule. There isn't this collection of "riflemen versus the world" arrangement, at least in the US system.

I'm not intimately familiar with the British TOE in dismounted units, but I do know enough guys there to be aware that there are a lot of similarities between NATO countries, and there are Mortar sections, machine-gunners, radio operators, forward observers, key leaders, and such. A single-caliber system would do those duty positions a great disservice as well, not to mention all the soft-skill drivers, cooks, mechanics, etc.

If the L85 had been built right from the start, the UK would be in a much better position, and is better-equipped to employ the L85A2 as a suitable PDW for those duty positions today, but it's still illuminating to see SAS & SBS use a heavy mix of Diemaco M4A1-type carbines with UK-made Mag58's as a GPMG for the primary small arms, now augmented with the L129A1.

LRRPF52

[stanc]

The Garand was only one weapon in the mix of Thompsons, BAR's, M1 Carbines, and Browning M1919 machineguns...

That's true, but the Garand was the one standard weapon for the majority of US riflemen. Thompsons were used in fewer numbers, and not by most members of an infantry squad/platoon. The BAR was the squad auto of its day. Your statement not only makes it sound as if the Garand saw only limited use, it ignores my point: that one caliber can be -- and has been -- successfully used for the standard-issue rifle and machine gun.

England had a much more viable cartridge at the time in many respected military professionals' opinion, and that was of course the .280 Enfield.

Which, ironically, was intended for a one-caliber system...

Does this shed a little more light on why a single-caliber system doesn't make sense?

Hey, I'm inclined to agree that -- all things considered -- a two-caliber system is better than a unified caliber. All I'm saying is that a one-caliber system can work well...providing the right cartridge is chosen, that is. Plus, for those concerned with fighting a future enemy equipped with hard body armor, 5.56x45 may be inadequate, and require a much more capable caliber.