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XM29 OICW

Prototype assault rifle with integrated grenade launcher

XM29 OICW

The XM29 OICW's elaborate design was promised to revolutionize infantry warfare, but its complexity was ultimately its own undoing

 
 
Entered service Cancelled
Caliber 5.56x45 mm NATO
Grenade caliber 20 x 85 mm
Weight (unloaded) ?
Weight (loaded) 8.2 kg
Length 890 mm
Barrel length 250 mm
Muzzle velocity 764 m/s
Cyclic rate of fire 700 rpm
Practical rate of fire 40 ~ 100 rpm
Magazine capacity 30 rounds
Magazine capacity (grenade launcher) 6 rounds
Sighting range ?
Range of effective fire ~ 500 m

 

   Designed as a replacement for the M203 grenade launcher, the XM29 OICW (Objective Individual Combat Weapon) was a cutting-edge weapon system that fully integrated both an assault rifle and a grenade launcher into a single weapon. However, the resulting weapon was instead too heavy, too expensive, too weak, and too unreliable for effective military use. Its conception and development is thus a cautionary tale for future arms designers to heed.

   The conception of the OICW concept was in a thesis named "Small Arms System 2000" (SAS-2000), published in 1986 by the US Army Infantry School at Ft. Benning. The central theme of SAS-2000 was that assault rifle technology evolution had reached its apex, and that because small arms in their existing form could improve no further, a completely new type of munition was needed. This premise went unchallenged, despite constantly improving conventional projectile technology, and ongoing advanced small arms programs at the time like ACR (the "Advanced Combat Rifle", which was to fire caseless ammunition).

   Further reinforcing SAS-2000 was a 1989 US Army TRADOC (Training & Doctrine) study, titled "The Small Arms Master Plan", or SAMP. This study called for the development of an OICW (Objective Individual Combat Weapon), Objective Personal Defense Weapon (OPDW), and the Objective Crew Served Weapon (OCSW). These were all meant to fire a "smart" airbursting 20 mm grenade, with the OICW and OPDW also having an assault rifle and submachine gun built in, respectively, while the OCSW was to be a pure grenade launcher for fire support purposes. SAMP further directed that these new weapons would utilize the latest advances in optics, sensors, computer technology, which would not only make these weapons both real and completely practical, but also allow them to enter widespread service before 2000.

   Despite the numerous, obvious, and significant risks that developing such a weapon entailed, the US Army was impressed enough by the SAMP paper to make these concepts an official requirement in December of 1993. SAMP also became a tri-service effort, resulting in the official program being named the Joint Service Small Arms Master Plan (JSSAMP), and the three weapons themselves as the OFSA (Objective Family of Small Arms).

   Two prototypes of the OICW were called-for, made by competing teams of manufacturers, and by 1997 the design that was selected was the Alliant Techsystems/H&K/Contraves Brashear model. The program grew rapidly in scale and funding, but the OICW's evolution did not; it did not receive type classification as the XM29 until 2002, by which time live fire testing of its 20 mm grenade launcher had only just begun. However, this was only the beginning of the XM29 OICW's troubles, as numerous problems in its design and construction were found, but solutions were not, despite the program retaining a significant percentage of its funding.

   The XM29 OICW has a distinctive appearance, being extremely large, bulky, and tall, with a broad casing around both of its weapons, and a large, boxy telescopic sight. The grenade launcher portion of the XM29 OICW is a self-loading, semi-automatic, gas-operated weapon, fed by a 6-round detachable box magazine, but little other information on this weapon has been published. The carbine section is a derivative of the H&K G36K. It is gas-operated, with a rotating bolt and short-stroke gas piston, and has a selective fire capability. For more information on the internal workings of this weapon, see the page on the G36.

   As is immediately obvious by the weapon's appearance, the OICW had very poor ergonomics. The carbine section cannot be used as a “standalone” weapon, because it has no sights or buttstock of its own. The grenade launcher us also unusable by itself, as it lacks essential ergonomic features for standalone use, such as a foregrip. Most of the controls for the weapon are located in the carbine section, further eroding the possibility of using the grenade launcher as a standalone weapon. Aiming the rifle and keeping the scope properly aligned both also presented a serious challenge, due to the substantial height difference between the scope and the 5.56 mm barrel.

   The design requirement for the OICW's weight was to be no more than 6.2 kg when loaded, but it instead weighed 8.2 kg. Upon discovering this, the US Army planned to have the weapon lightened, but only to 7 kg, and the poor balance of the design meant that three-quarters of its weight had to be carried on one arm. To put it another way, although the OICW is supposed to replace an 3.26 kg assault rifle with a very small, light, and compact grenade launcher attachment, the 8.2 kg OICW is actually a kilogram heavier than the 7.1 kg M249 SAW light machine gun.

   The most serious issue with the carbine is that the 250 mm barrel isn't long enough to impart sufficient kinetic energy into military 5.56 mm projectiles to make them lethal at rifle engagement ranges. Particularly notable is that the projectiles won't fragment inside the target at typical infantry engagement ranges, and fragmentation is what gives military 5.56 mm ammunition most of its lethality. For example, the M16's 508 mm barrel produces a muzzle velocity of 922 m/sec, allowing the M855 Ball projectile to fragment on impact as far out as 150 m. The M4 has a shorter 308 mm barrel, allowing for 825 m/sec, and has unsurprisingly performed poorly in combat compared to the M16, thanks largely to a maximum fragmentation range of only 12-15 m. That said, the XM29 OICW fires the same ammunition, but only has a 250 mm barrel, with a muzzle velocity of only 764 m/sec; the resulting lethal range of the OICW is thus more on-par with a small-caliber submachine gun than a typical assault rifle, despite firing the 5.56x45 mm NATO round.

   Even the grenade launcher proved too weak in practice. Because the 20 mm grenades are so small and light, and because they contain large quantities of sensors and circuitry, very little of their mass is in their bursting charges. Compared to a 40 mm grenade, the 20 mm grenade has less than 1/4 of the explosive filler. Moreover, the 20 mm shells were designed in the early 1990s to defeat PASGT armored vests, which had become obsolete by two generations by the time the OICW's prototypes began their developmental testing. It has never been clarified whether the 20 mm HEDP grenade concentrated most of its blast force directly forward (which would make it effective against body armor, but not against area targets), or equally dispersed it like a 40 mm HEDP grenade (the only way it would be effective against even adjacent targets, but it would also make the munition useless against most body armor).

   Either way, the official position that the 20 mm grenade was equally effective for both of these purposes was highly implausible. A French Army study on the matter of sensor-fused grenades came to the conclusion that the smallest sensor-fused grenade that would still be able to carry an adequate bursting charge would have to be at least 35 mm in bore. As a result of this finding, the GIAT company developed the similar PAPOP rifle/launcher weapon to use a 35 mm grenade; though ultimately, as a result of similar problems as those with the OICW, the PAPOP was cancelled.

   The emphasis on firing these grenades on as flat a trajectory as possible also entailed that hitting targets behind vertical cover would be exceedingly difficult, as the projectiles aren't "lobbed" like conventional rifle grenades. Moreover, by designing the 20 mm HEDP round for a proximity-triggered airburst instead of exploding on impact, their proximity fuzes had the potential to cause the grenade to detonate too early to defeat the target, if it came too close to another object or the ground during flight. This problem was encountered with several other such "smart" munitions during the OICW's development, notably the M830A1 MPAT (a 120mm dual-purpose HEAT round developed for use by the M1A1 Abrams and M1A2 Abrams).

   At a later date, the US Army planned to replace the 20 mm grenade launcher with a 25 mm weapon. However, it is unclear whether this was ever accomplished. Even if it were, it would only worsen the cost-size-complexity spiral of the OICW; the program cost would be significantly increased by such a huge departure, while the size, weight, and complexity of the weapon itself would significantly increase for obvious reasons.

   Many other technologies used as selling points for the OICW ultimately failed to materialize. These include combustible case rifle ammunition, a wireless interface, weapon recoil reduction systems, target acquisition capability, and extensive usage of composites in the weapon's construction. As seen above, promised feats such as "500 percent increase in probability of incapacitation", "Effective range to 1 000 meters", "Substantial weight reduction", and "Ergonomic design" also proved unfeasible.

   Another significant issue with the XM29 OICW was its power supply. The infrared sight, fire control computer, and grenade launcher would all require a significant power output over a long period of time, entailing that a large and heavy power source would have to be integrated into the weapon system. This not only further increased the OICW's cost-size-complexity spiral, but also resulted in another expensive, bulky, and finite resource the weapon would be inoperable without, along with its ammunition. Furthermore, having the infantryman carry an external power supply for the weapon was implausible, because the Land Warrior system the OICW was meant to be integrated into was already experiencing crippling weight, power source, and power usage problems of its own.

   However, the most serious problem with the grenade launcher has seemingly gone unnoticed by the military and the press alike. The objective of using grenades to attack personnel with body armor directly using explosive charges also presents an intractable legal problem under the Law of War. Specifically, by deliberately designing the 20 mm grenade with the intent of shooting enemy personnel wearing body armor using an explosive projectile, the 20 mm HEDP round is thus an "exploding bullet", which are illegal for military use under the Law of War. By contrast, 40 mm grenades are designed to incapacitate personnel by exploding *near* them, while explosive ammunition for such weapons as the Barrett M82A1 anti-material rifle is permitted on grounds that it is fielded exclusively for engaging vehicles and small structures.

   Another issue is that the XM29 OICW was more expensive than it was worth, with a projected unit cost of $10 000, while an M16 and an M203 each cost only $1 000. The OICW's advocates have claimed that an M16/M203 weapon with a similar fire control system to the OICW would have to cost at least $35 000; however, no such weapon existed to draw a comparison with to justify this figure. Moreover, the $2 000 M16/M203 neither includes nor requires an electro-optical fire control system to aim it, so this weapon combination would actually be cheaper by a factor of five.

   The $35 000 claim is also rather interesting in hindsight, as when the XM25 entered service in 2010, this weapon itself had that exact unit cost --- and unlike the XM29, the XM25 was a pure grenade launcher without a carbine built-in. Given that the G36 has roughly the same unit cost as the M16A4, and its conversion into the XM8 and then into the 5.56 mm weapon built into the XM29 would likely significantly increase its development expenses, the XM29 would most likely have cost about $40 000 if it were introduced into service in 2010. This figure also excludes a significant and inevitable sum of additional R&D funding that would be required to correct the OICW's lingering operability issues.

   Similarly, one of the qualifiers for introduction into service was that the 20 mm grenades were not to exceed $25 in unit cost, which they had overshot (pun not intended) by a factor of 6, instead costing $150. Even if the $25 objective were achieved, the 20 mm grenades would still be cost-ineffective, and 40 mm HEDP grenades each cost just $8.

   It is ironic that the XM29 came to be designated the Objective Individual Combat Weapon, as this designation doesn't fit the weapon at all. "Combat Weapon" is a redundant description, because military weapons are obviously created specifically for combat purposes; the "Individual" descriptor is also misleading, because the XM29 is too heavy for a single soldier to wield in a combat situation, and isn't intended to be carried in separate pieces between multiple soldiers; finally, the XM29's design formula is the product of a planning and evaluation process that was clearly not Objective. Similarly, there was also an attempt to re-brand the weapon as the Selective Assault Battle Rifle (SABR), a designation that was even more superfluous.

   The XM29 was originally planned to be fielded by 2005, but it was instead canceled on October 31st 2004. In July of that year, the rifle and grenade launcher efforts had been split into two separate programs, resulting in the XM8 assault rifle and the XM25 grenade launcher. The XM8 was itself cancelled in October of 2005, and the XM25 was badly delayed, finally entering service in 2010.

   The XM29 OICW was also meant also to be directly integrated into the US Army’s Land Warrior information system, which in turn was itself to be integrated into the Future Combat Systems. Like the OICW on a grand scale, both of these programs proved hopelessly unworkable as a result of their complexity; and like the OICW, they too were cancelled in the 2000s.

 

Related weapons

 

   XM8: It is essentially a H&K G36 modified for licensed production in the US, and design basis of the XM25's 5.56 mm rifle component. Cancelled in 2005.

   XM25 CDTE: Grenade launcher employing related technology to the OICW's 20 mm launcher, but fires a 25 mm grenade. Entered service in 2010, but currently facing cancellation over numerous problems.

   XM307 OCSW (also called the ACSW): Automatic grenade launcher chambered in the same 25 mm grenade as the XM25. Cancelled in 2007.

   K11: South Korean weapon extremely similar in design to the XM29. Entered service in 2010, but remains problematic and unreliable.

   ZH-05: Chinese assault rifle with integrated grenade launcher, inspired by the XM29. China attempted to produce an advanced infantry weapon for its future soldier program. There is no reliable information if the ZH-05 is in service with the Chinese army, or how many of these weapons were produced.

   Neopup PAW-20: South African grenade launcher similar to the XM25, but firing 20 mm shells similar to those used by the XM29. Entered service in 2010, but continues to suffer problems not unlike those in the XM29 and XM25.

   PAPOP: French equivalent of the XM29, but firing a larger 35 mm grenade. Program abandoned at an unknown date.

   A standalone 20 mm grenade launcher variant was planned, but it appears that no such weapon was actually developed.

 

Blacktail

   Article by BLACKTAIL

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