5.56x45 mm NATO
20 x 85 mm
Cyclic rate of fire
Practical rate of fire
40 ~ 100 rpm
Magazine capacity (grenade launcher)
Range of effective fire
~ 500 m
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
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
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
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
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
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
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
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.
is essentially a
modified for licensed production in the US, and design basis of the
XM25's 5.56 mm rifle component. Cancelled in 2005.
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.
(also called the ACSW): Automatic grenade launcher chambered in the
same 25 mm grenade as the XM25. Cancelled in 2007.
Korean weapon extremely similar in design to the XM29. Entered
service in 2010, but remains problematic and unreliable.
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.
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.
French equivalent of the XM29, but firing a larger 35 mm grenade.
Program abandoned at an unknown date.
20 mm grenade launcher variant was planned, but it appears that no
such weapon was actually developed.
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