China has arming its troops with the new ZH-05, a weapon that combines a 5.56mm assault rife with a computer controlled 20mm grenade launcher (with a max range of 700 meters). The ZH-05 has been seen with Chinese marines sent abroad warships working with the Somali anti-piracy patrol. Chinese special operations troops have the ZH-05 and the army ordered several thousand of them so that each four man infantry fire-team will have one. That puts China ahead of the other two countries (United States and South Korea) with similar weapons. The Chinese version is lighter, simpler and cheaper and the Chinese feel the ZH-05 is worth buying and issuing to the troops. There’s not been similar enthusiasm with the American and South Korean versions.
The U.S. began working on this type of weapon back in the 1990s as the OICW (Objective Individual Combat Weapon) and that mutated into the XM25 (the “X” in XM25 designates a system that is still in development). The South Korean one is the K11. The three weapons are different in important ways. The American and South Korean weapons both have a magazine for the computer controlled grenades while the ZH-05 is a single shot weapon, requiring 20mm rounds to be loaded manually each time. This makes the ZH-05 the lightest of the three weapons, weighing five kg (11 pounds) loaded (with a single 20mm round and a magazine with 20 rounds of 5.8mm ammo). The M25 got rid of the assault rifle element and upped the caliber to 25mm. Thus an M25, with a four round magazine, weighs 5.5 kg while the K11, loaded with a 20 round 5.56mm and five round 20mm magazines weighs 7.2 kg. The M25 is the only one of three to have been tested extensively in combat but because of misfire during a demonstration, budget cuts and troops finding there were not really that many situations calling for the M25, the system was cancelled (development funding was eliminated) in 2013.
The initial spectacular success and popularity of the XM25 grenade launchers in Afghanistan led the army to request that the weapon enter regular service as the M25 in 2014. But Congress, looking for ways to reduce military spending in 2013 cut all money for the M25. The army managed to scrounge enough cash to keep the M25 on the books and hopes to get the money to build 1,100 of them. Currently the M25 cost $35,000 each with the 25mm ammo going for $55 per round. SOCOM (Special Operations Command) apparently has some M25s but with few American troops in combat there is not a lot of demand for a weapon like this.
When the first evaluation models of the XM25 arrived in Afghanistan in 2011 the weapon soon became much sought after by infantry troops. There were never more than a few dozen XM25s in Afghanistan and limited supplies of ammunition. Despite that the weapon quickly developed a formidable reputation. The Special Forces have priority on the weapon because it is very useful for special operations missions. The army planned to buy enough so that they could issue one per infantry squad. There are 27 squads in an infantry battalion.
The XM25 grenade launcher went through several major design changes and it wasn’t until 2005 that the first XM25s were delivered to the U.S. Army for troop testing. In 2007 a few were sent overseas for testing in combat situations. While the troops have been very enthusiastic about the new weapon, there were a lot of suggestions, mostly about minor items. So the army kept tweaking and refining the weapon. It appeared that the XM25 was a success after only 55 of the 25mm rounds were fired in combat. The users protested having to give them up after the few months of field testing. All this was because the XM25s worked as advertised, firing "smart rounds" that exploded over the heads of Taliban hiding behind rocks or walls, or hiding in a cave or room. Enemy machine-guns have been quickly knocked out of action and ambushes quickly disrupted with a few 25mm shells. Encounters that might go on for 15 minutes or longer, as U.S. troops exchange fire with hidden Taliban, end in minutes after a few 25mm, computer controlled rounds were used. But over time it was found that there were not that many situations in combat calling for an M25 and some troops left them behind most of the time.
The XM25 was originally one of two weapons (the other being a 5.56mm rifle) incorporated in the 8.2 kg (18 pound) XM29 OICW. The OICW was originally developed as a replacement for the 40mm grenade launcher attached to the grenadiers M16 as well as providing a more accurate and capable grenade launcher. Didn't work out as intended. The big problem was effectiveness. The older 40mm, unguided, grenade rounds weigh 540 grams (19 ounces) each, the original 20mm OICW round weighed half that. This was one of the several major problems with the OICW. It was too heavy and ungainly, and the 20mm "smart shell" it fired did not appear capable of effectively putting enemy troops out of action consistently, especially compared to the 40mm shell it was replacing. So, in August, 2003, it was decided to take the 5.56mm portion out of the OICW and develop it as a separate weapon (the XM8) while the grenade launcher part that fired the "smart shell" continued development as the XM25. But the XM-25 would now use a 25mm shell, which would generate 50 percent more fragments (and heavier ones at that) than the 20mm shell of the OICW. China and South Korea insist that their 20mm grenades inflict sufficient hurt on the enemy to be effective. The U.S., with lots of combat testing believes that 25mm is the only way to go. China disagrees and insists its 20mm shell is quite lethal.
The 20mm and 25mm "smart shells" both use a computer controlled fuze. The XM25 operator could choose one of four different firing modes via a selector switch on the weapon. The four modes include "Bursting" (airburst). For this to work, the soldier first finds the target via the weapons sighting system. The sight includes a laser range finder and the ability to select and adjust the range shown in the sight picture. For an air burst, the soldier aims at an enemy position and fires a round. The shell is optimized to spray incapacitating (wounding or killing) fragments in a roughly six meter (19 foot) radius from the exploding round. Thus if enemy troops are seen moving near trees or buildings at a long distance (over 500 meters), the weapon has a good chance of getting them with one shot. M-16s are not very accurate at that range, and the enemy troops will dive for cover as soon as M-16 bullets hit around them. With smart shells, you get one (or a few) accurate shots and the element of surprise. The smart shells can be used out to 700 meters, but not as accurately. At those longer ranges, you can't put a shell through a window, but you can hurt a crowd of gunmen standing outside the building.
The other modes are "PD" (point detonation, where the round explodes on contact), PDD (point detonation delay, where the round detonates immediately after it has gone through a door, window or thin wall) and "Window", which is used for firing at enemy troops in a trench, behind a stone wall or inside a room. The round detonates just beyond the aiming point. For buildings, this would be a window or door frame, cave entrance or the corner of a building (to get enemy troops thought to be around the corner.)
The XM25 is still a heavy weapon, with the final version coming in at 5.5 kg (12 pounds). The 25mm shells weigh over half a pound each (270 grams). On the plus side, there is already a 25mm armor piercing round (using a shaped charge capable of penetrating over 50mm of armor) available. This makes the XM-25 capable of knocking out light armored vehicles. Then there are the types of 25mm ammo, like fuel-air explosive (or "thermobaric"). Such a shell would cause greater blast effect in an enclosed space, and actually suck most of the oxygen out of a cave or closed room long enough to make surviving troops at least a bit groggy. This gives the attacking troops an opportunity to rush in and kill the enemy or take prisoners. In combat, every little advantage helps. With the XM-25, hiding behind rocks, trees, walls or in caves will no longer protect you. There is also a flechette ("shotgun") round. The XM-25 also has a 4x thermal sight.
It was only in 2009 that South Korea revealed it had developed the K11, a $14,000 20mm/5.56mm weapon which appeared to be identical in concept to the U.S. Army XM29. The South Korean version weighs 6.1 kg (13.4 pounds) empty and combines a 5.56mm rifle, with one firing 20mm computer and laser controlled shells. The South Korean weapon appears to operate the same way as the 20mm shell of the XM-29. The South Koreans plan to issue the K11, on the basis of two weapons per squad (an infantry unit containing 10-12 men). The K11 was both cheaper and lighter than the XM29.
It's unclear if the South Koreans found solutions to the problems the XM29 and XM25 encountered, or simply developed an improved XM29 and decided it was useful in small numbers. South Korea used some K11s in Afghanistan and there were lots of complaints about reliability and effectiveness. This did not result in the K11 being cancelled, but the weapon does not have a good reputation among the troops. The South Koreans have found that the 20mm smart shell is effective out to about 500 meters. South Korean troops began receiving the K11 in 2010. In 2011 South Korea halted production of the K11 for a while because nearly half of those already distributed to the troops had design or manufacturing problems. This included some that had been sent to South Korean troops in Afghanistan. The K11 problems were fixed and so far over 4,000 have been built. The K11 manufacturer insists that problems have been fixed but troops and many commanders are not so confident.
The Chinese ZH-05 has three types of 20mm ammo. One is impact detonation, the second is air burst and the third is a shotgun type shell. The computerized fire control system only provides for the user to select at what range the air burst round will detonate. Because these 20mm rounds have fewer electronics in them they carry more fragments and the Chinese believe (but don’t know from combat experience) that this supplies adequate wounding capability.