The Art & Science of Defensive Planning

The recent overrun of COP Keating (http://ricks.foreignpolicy.com/posts/2009/10/10/the_battle_of_cop_keating_an_earwitness_account) is too close a replay of Wanat for comfort. (http://ricks.foreignpolicy.com/posts/2009/01/28/inside_an_afghan_battle_what_happened_at_wanat_last_july_i). In both cases, an American unit is located on tactically unsound terrain, at the tip end of the logistic chain, and were overrun by the enemy assault. Only the belated arrival of air support saved the American bacon.

It appears that the US Army has gotten too relaxed after 20 years of living on Forward Operating Bases (Starting in Somalia). The logistic and security posture/doctrine these days are based on these brigade-sized FOBs. (If the Army still has an institutional security doctrine anymore.) To the extent that the Division staff (and above) think about security, it is from the stand point of Anti-Terrorism/Force-Protection. Maybe the Infantry School (& Ranger School) is still teaching tactical security and patrol base defense, but most Army officers have no training on this subject beyond that FM 7-8 (http://www.globalsecurity.org/military/library/policy/army/fm/7-8/index.html) they're supposed to read on their own. If you're one of these unfortunate officers, I urge you to pick up a copy of Millen's "Command Legacy" http://www.amazon.com/Command-Legacy-Tactical-Leaders-Revised/dp/159797207X/ref=sr_1_1?ie=UTF8&s=books&qid=1256222637&sr=8-1 . It's a great book filled with concrete TTPs and discussions. You have a defense plan that you can pick up from the book to use, and he explained all of his reasons so you can adapt it on your own. Even infantry officers will get a lot out of this book. Granted, Millen's chapters on defense are based on a Mobile Defense, where you have a Battalion Reserve to come save you. On the other hand, in a patrol base defense like Wanat & Keating, you site your positions around the center, and have a parameter wall. The basic principles are the same.

As we go into the world of Resilient Communities, some of you may find the need to brush up on defensive planning. Millen's book is an excellent starting point. Just remember that you need at least a platoon of people to defend your hamlet.

LMG, Assault Rifles, & Infantry Squads

Alter has some questions about LMG magazines. Sorry about the delay in my reply here. I will also talk about how assault rifles has changed the infantry squad, and squad operations in general.

1.) Drum magazines: Yes, reloading drums can be slow. However, in a fire fight session, soldiers rarely have time to reload their magazines, so the loading time is not an issue.

For the US Army, the basic load for a SAW gunner is 600 rounds. A 200 round belt and box is 6.92 lbs, whereas 200 rounds in BetaCo drum magazines is 8.8 lbs, and in 30 round magazines 7.5 lbs. The belt-feed mechanism (top cover) on an M-249 is about 0.75 pounds [from memory], so given the basic load, belt-feed would be lighter. 30-round magazine feed is a close second, though.

2.) Top-loading vs optics: you can angle either the feed or the optics. Angling the magazine well would also help with changing the magazines and reduce the exposed profile of the gun crew during reloading.

3.) Configurable components: ARES's Shrike is a great example of a modular weapon system, with various barrell lengths and belt feed vs magazine feed. However, soldiers generally will leave all of the components behind in the barracks and will deploy with a single configuration.

With the invention of the fully automatic Assault Rifle in World War II, the Light Machine Gun has become much less critical in squad operations. A fire team of 4 full-auto assault rifles can keep up a fire volume similar to that of a fire team with 1 LMG and 3 semi-auto rifles. Therefore, today, infantry squad armament is more a reflection of philosophy than fire volume arithmatics.

There are two schools of thought in infantry squad armament: Generalists vs Specialists. The Specialist school is exemplified by WW2 Stormtroopers and modern American squads: you have riflemen/marksmen, machine gunners, grenadiers, and submachine-gunners in a squad. Each man specializes in a weapon system. In a squad attack, he has a designated role based on his weapon system. He may cross-train on the other weapons, but he is supposed to be an expert of his weapon.

The Generalist school is exemplified by the French All-FAMAS squad. Everyone uses a full-auto-capable, high rate-of-fire, assault rifle. In the Generalist squad attack, the focus is more on the tasks than the weapons: Suppression, indirect fire (rifle grenades), marksmen, and close-in/breach/demolitions. Over time, the squad members end up specializing anyway, but at least their assault rifles help them do everything when necessary.

In an attack, squad/platoon fire (as opposed to maneuver) has two main tasks: suppressing a bunker and cutting off enemy reinforcement/maneuver. A machine gun suppresses the bunker by firing at it as a target. A rifle does so by aiming and firing at the bunker's firing ports/holes. Similarly, the machine gun cuts off maneuver by firing at the group, while the rifle fires at the individual maneuvering. So in the attack, the Specialists and the Generalists engage the same targets; they just go about it differently.

In the defense, the Specialist squad acts different from the Generalist squad. The Specialist squad defense is organized around its LMGs. The LMGs focus on the enemy attack axis, and the rest of the squad focuses on protecting the LMGs. At the same time, the squad needs to site the LMGs away from the other fighting positions, because the LMGs draw fire from the enemy. So the defensive line tend to be a series of one- and two-men foxholes.

The Generalist squad defense also orients on the enemy attack axis. However, it relies on 3- and 4-men fire teams to generate the fire volume (to approximate LMGs). So the defensive line tend to be section trenches (short trenches for the team) or fire team strong points. A fire team strong point can be either one large foxhole or two smaller foxholes right next to each other.

Regardless of the squad armament, both schools have medium machine guns (or general purpose machine guns) at the platoon level. The machine gun may not be critical in the platoon attack, but its value shines through in the platoon defense. Much as its historical role since World War I, the machine gun is a force-economy tool in the defense: A platoon can cover its sector with just the machine guns. It can keep the rest of the soldiers resting and/or under protective cover. At the moment of attack, the machine guns give time for the defenders to get on the firing line.

The reason the Generalist squad can get away without an LMG is because a squad is always part of a platoon defense. A ten-men squad cannot defend a location on its own for long. It can barely keep up an LP/OP while staying on 50% security. Because the platoon MMGs are always available in the defense, the Generalist squad does not need an LMG.

Hope you find it useful in understanding squad operations and machine guns.

Edited to add links and labels.

Modifications to Improve Reliability of Short-Barreled M-16 Variants

The Small Arms Review, which is an awesome firearms magazine, has been running a series of interviews with various firearm designers, such as Arthur Miller, Reed Knight, Dr. Philip Dater, et al. The interviews are great, with lots of insights into designing firearms and making design tradeoffs. Unsurprisingly, many of these designers are connected to the M-16 system in one way or another, due to its prominence as the last successful American rifle design to have wide acceptance.

In OIF and OEF, there have been documented reports of unreliability with the M-16 and its derivatives, the M-4 and the Mk-18 CQBR. Soldiers' failure to clean their weapons contributes to some of the reliability problems. However, the rest of the reliability issues may be design-related, and several of the designers above discussed this topic with Small Arms Review in the interviews.

In particular, in the March, April, and May 2008 issues, Jim Sullivan talked of the design problems he dealt with in designing the M-16, and how they have contributed to the current reliability problems. Jim Sullivan was one of the lead designers to complete the AR-15/M-16 design. Mr. Sullivan said that the current M-4 reliability problems come from barrel heating. According to him, the 5.56mm cartridge, because of its straight case design, is very sensitive to barrel heating over the course of many shots. The chamber pressure from the gunpowder expands the case against the chamber of the barrel. As the case temperature increases, it pushes harder against the barrel chamber. Normally, there is enough time for the case to cool and relax (and depressurize) before case extraction starts, which pulls the case out of the chamber and ejects it. However, if the extraction starts earlier than designed, such as with the M-4 and other shorter variants, the case is still pushing against the chamber during extraction. This "sticking" to the chamber exerts a friction force against the extraction, which may be strong enough to cause weapon failures. During a long firefight or range session, the rifle barrel heats up over time. The barrel heating causes the chamber to expand itself, decreasing the clearance between the chamber and the cartridge case. This sticking process, according to Mr. Sullivan, is the cause of the M-4 reliability problems, and is a concern for all 5.56mm weapons with a barrel length of less than 16 inches. (The M-4 has a barrel length of 14.5 inches.)

The Russians avoids this problem entirely by using a highly tapered case for its 7.62x39mm and other rifle cartridges. As the case expands, it also pushes itself away from the chamber, due to its case taper. For the Russians, barrel heating and case heat improves extraction, and they can go with a shorter barrel for their compact carbines with no reliability issues.

For us Americans, however, we're stuck with the 5.56mm cartridge for the foreseeable future. The federal government's budget problems means there is no money to change our service cartridges. Therefore we need to find low-cost fixes for our M-4 carbines, which is coming into wide use in the US Army and the USMC. In fact, the Army is making the M-4 its standard soldier weapon, replacing the M-16. To deal with the chamber sticking problem, there are two main methods: increasing cycle length to give the cartridge case time to cool, or decrease barrel heating to draw heat out of the cartridge case.

One way to decrease barrel heating is to install a heat sink onto the chamber end of the barrel. The POF-USA piston operation system has a barrel nut that also doubles as the heat sink. The heat sink may contribute to the reliability of POF's weapons as much as its gas piston system. In addition, a non-free-floating rail forearm can work as the heat sink as well. [The link shows a free floating rail system. There aren't many non-free-floating railed forearms on the market. A non-free-floating forearm clamps onto the barrel, thus drawing heat, whereas a free floating forearm does not contact the barrel.]

The other approach is to increase cycle length, but Colt has already exploited this approach with the M-16 and the M-4 currently in service. Colt re-designed the buffers to slow down the bolt carrier during the ejection process. The modified buffers make the M-16 somewhat reliable, but is not an adequate solution for the M-4.

The AR-15 commercial market is debating the merits of the gas impingement system versus the piston/operating-rod system on improving AR-15/M-16 reliability. The piston/operating-rod system changes the force pushing on the bolt carrier, but as Mr. Sullivan says, that's not necessarily the solution. The root of the reliability problem comes from the barrel heating/cartridge sticking. This phenomenon is the result of prolonged rapid fire through the weapon, which is not how most users use their weapons. For most users, the current M-4 and CQBR configuration is adequate for their needs. For users who need to engage in prolonged rapid fire, though, they need to consider installing heat sinks on their barrels.

For the users who are looking for a short-barreled rifle/personal defense weapon, the cartridge sticking is a factor they need to consider in evaluating the market. As the barrel gets shorter, the problem becomes more pronounced.

In a later article I will evaluate the effectiveness of the Picatinny railed forearm as a heat sink.

Chinese Weapon Engineering Textbooks

Just came back from a personal trip to Beijing. The bookstores there are very impressive. Of course they have the small hole-in-the-wall, mom-and-pop bookstores. The super-bookstores, though, are multi-story affairs. They have at least three floors dedicated to books, one or two floors for CDs and DVDs, and floor space for stationery and other products. The bookstore in Sidan district has 1.5 floors for consumer electronics, with a focus on electronic dictionaries. Each of these floors is about the size of a one-floor Barnes & Nobles. And these stores are all packed! The three super-stores I visited are all filled with people browsing and purchasing books. Even on a weekday during school hours the stores are still busy. I just don't know if I can go back to Barnes and Nobles anymore after this trip.

One particularly impressive area is in the engineering textbooks. As an engineer, I just had to go check that out. If you go to a Barnes & Nobles here in the states, you will find about 8 to 16 shelves (1-2 short aisles) for engineering, programming, and "technology" books. In the Beijing super stores, the engineering section takes up at least a quarter of a floor. Mechanical engineering itself takes up at least 8 shelves. Food processing/manufacturing takes up several shelves, too. Even weapons/military/aero/astro engineering has about 3 to 4 shelves, more if you include the shipbuilding shelves. Civil engineering and architecture/construction occupies half of the whole engineering section, which is notable from an American perspective, where the undergrad civil engineering departments are usually the small departments in the engineering schools (approx 10-20 students/class year).

The military engineering books seem good. You get some fluff there, like a "modern weapon catalog" that is the size of a pocket book, but the rest are pretty solid. I saw "Principles of Submarine Design", "Principles of Fire Control System Design", "Design of Automatic Firearms", and "Introduction to Propellant Design", to name a few. I flipped through these books and they all seemed to cover the basics, with plenty of equations to start component designs and instructions on how to make the design tradeoffs. Good textbooks. It is sad that books like these are not more accessible to the American public, or even the American engineering students.

Because of the current Chinese emphasis on space flights and ballistic missiles, rocketry is pretty big in the military/aero&astro engineering book section. The books cover all segments of rocket/missile design. They even have an "Artillery Rocket Design" translated from the original Russian textbook.

All in all, it was very impressive visiting these bookstores. They are definitely on the to-see list for anybody visiting Beijing.

Does any of you know how the bookstores are like in India's major cities? How are their engineering books selling?

PS: edited for grammar

The Upcoming LMG Replacement and Infantry Operations

The Marine Corps Times reports that USMC is working on a SAW replacement. At the same time, the US Army will probably stay with an upgrade to the FN Minimi/M249. The Marines are looking for a magazine-fed-only automatic rifle to serve in this role. The Army, on the other hand, is sticking with belt-feed, and will possibly eliminate the magazine well on the SAW.

This is an interesting development and serves to highlight the historical role of the light machine gun. Most people, including many in the military, have little understanding on what a machine gun is supposed to do. Everyone agrees that a machine gun, including an LMG and automatic rifle, needs to shoot lots of rounds, but outside of that, there's quite a bit of confusion.

Man invented the Machine Gun because it was a great engineering problem, to make the gun automatically load and continuously fire. But after the invention, militaries struggled for years to build up an organization around the technology. Eventually, in the meatgrinder of World War I, they settled on the missions of the machine gun as:
1. In the Defense, to anchor the defensive line, and to build a wall of lead to stop the enemy advance.
2. In the Offense, to isolate the objective (a bunker, foxhole, house) so that the enemy cannot reinforce the target, and to occupy the objective's attention while the rest of the squad/team approaches the objective.

The light machine gun attempts to meet these two missions for the infantry squad, while the medium machine gun does the same for platoons and companies. To keep up with the soldiers on foot, the LMG needs to be small and light enough so that one soldier can carry it and bring it into action, yet still fulfills the above two missions.

The current debate in LMG design is, What are the necessary features to meet the missions?
-Does it require a belt-feed mechanism so we can give it a 200-round belt in a sustained-fire mode, or would the current 30-round magazine be sufficient since machine gun operation usually has enough time to allow a quick magazine change? Can the current 90-round and 100-round drum magazines work as well as the battle-proven belt-feed mechanism? The American BAR served throughout WWII in the LMG role with only a 20-round magazine.
-Does it require a quick change barrel so that the squad can fire thousands of rounds in a defensive engagement against overwhelming odds? Without changing out the barrels in this scenario, the machine gun barrel will melt/deform from the firing stress, rendering the weapon useless.
-Does it need a tripod mount so we can mount it on a Humvee, and to provide accurate, long-distance(600m+), automatic fire from a static position? Or is that a role for medium machine guns and heavy machine guns, but not light machine guns?

These questions are important because modern assault rifles such as the AK47 and M16 provide automatic fire mode to the individual soldier. The soldier no longer has to rely on the squad LMG to be the sole provider of automatic fire. The LMG does not have the overwhelming advantage in automatic fire to offset its disadvantage of weight, size, and logistical and training requirements (as a result of its belt-feed, barrel, and tripod). And without the above three features of belt-feed, quick-change barrel, and tripod mount, the LMG looks suspiciously like any other assault rifles. Witness the RPK and the L86 LSW variant. In fact, the British Army now employs the L86 LSW as a designated marksman rifle, rather than an LMG.

[The Steyer AUG LMG variant is an LMG design that has the quick-change barrel, but no belt-feed nor tripod.]

So armies across the globe continue to grapple with the design of the LMG/Automatic Rifle. The lessons of OIF are now feeding into this debate. In OIF, most of the fighting is done in built-up areas. In such close quarters, the machine guns primarily serve to isolate the objective, firing down alleyways to keep people from entering and leaving. The LMG's length means that it is of limited utility inside houses, going from room to room. The LMG's range is useful as a marksman rifle, but its sustained fire is rarely used due to collateral damage. To the dismounted patrol, then, the LMG extracts a weight penalty for a limited tactical utility.

On the other hand, the LMG was crucial in the early days of OIF phase 4. At the time, units across the country scrambled onto Humvees to maintain security on the lines of communication, and to provide security coverage in the cities. During this mad rush, there was a critical shortage in medium machine guns (M240) and heavy machine guns (M2) to arm the Humvees. The SAWs in the pintle mount bridged the shortage then, and has continued in the role to this day as a vehicle weapon. Therefore, an LMG may be important to the infantry squad not for its dismounted utility, but as a hedge for the days of the Dragoons.

In conclusion, the Light Machine Gun, as it exists today, will probably fade away. In the assault-rifle world, the LMG does not possess enough of an advantage over the assault rifle to continue on as a dedicated platform. Instead, we will see more assault-rifle derivatives such as the Steyer AUG LMG, which shares much in common with the individual rifle. The automatic rifle of the future would ideally have a quick-change barrel and the tripod mount (to get on the pintle). Drum magazines and regular magazines will carry the ammunition for the automatic rifle, enabling the SAW gunner/Automatic Rifleman to share ammo with his squadmates.

Thanks to Noah's Five for Fighting 9/16/08 for the heads up.

Edited for spelling, grammer, and formatting