When the U.S. Army introduced its 18 ton Stryker 8x8 wheeled ICV (Infantry Combat Vehicle) in 2002 it was meant to equip the new medium brigades. The Stryker ICV had ten variants. In addition to the basic turretless M1126 IFV (Infantry Fighting Vehicle) for infantry, the other variants were for reconnaissance (M1127), a 105mm assault gun (M1128), a mortar carrier (M1129), command post (M1130), fire support (M1131), engineering support (M1132), ambulance (M1133), anti-tank (M1134) and NBC (Nuclear, Biological, Chemical) reconnaissance (M1135).
Fifteen years later the army introduced the Stryker A1 with a V-shaped double bottom (to handle bomb and mine explosions) a lot of new equipment inside and a turret armed with a 30mm autocannon (similar to the 25mm one used on the M2 tracked IFV). The A1 version can carry nine infantry in addition to the three man vehicle crew. The A1 has better protection and communications as well as “surround view”; a system of vidcams built into the hull that enable crew and passengers to see what is happening all around the vehicle via flat screen displays in the vehicle.
The original Stryker design called for a 12.7mm machine-gun mounted up top but no turret plus another 7.62mm machine-gun operated from one of the other top hatches. When the first Stryker brigade was sent to Iraq in 2003 the ICV version was armed with the PROTECTOR Remote Weapon Stations (RWS), which later got a thermal sight and full stabilization. The RWS became standard with a 12.7mm ring mounted machine-gun as secondary armament. In combat, the RWS was the main weapon and reduced crew casualties while also providing much more effective firepower. The RWS used on Stryker was a key component of the CROWS (common remotely operated weapon stations). This idea has been around for nearly half a century, but years of tinkering and better technology had, by the 21st century, made the remote control gun turret finally work effectively, dependably and affordably. CROWS was a real lifesaver, not to mention anxiety reducer, for troops who drive through bandit country a lot, and man the turret gun. You're a target up there, and too often, the bad guys get you. Not with CROWS. The gunner is inside the vehicle, checking out the surroundings (with night vision and telephoto capabilities). CROWS also has a laser rangefinder built in, as well as a stabilizer mechanism to allow more accurate fire while the vehicle is moving. The CROWS systems cost about $260,000 each (including the weapon), and can mount a variety of weapons (M2 .50 caliber machine-gun, MK19 40-mm automatic grenade launcher, M240B 7.62mm machine-gun and M249 5.56mm squad automatic weapon).
CROWS was but one of many new, or improved, electronic systems in Stryker and that was one of the things that made this wheeled armored vehicle very popular with its users. The troops using Stryker very much appreciated that they had a vehicle they had to "boot up" rather than just start up. The downside of that was recent exercises in Eastern Europe, near the Russian border, that resulted in numerous Russian efforts to hack the Stryker systems. The army won’t reveal any more than that but even before the Russian border incident, there was a major effort to protect the electronic networks in the Stryker.
As useful as the all the new electronics and the RWS was on the Stryker, a heavier, longer-range weapon like 25mm or 30mm autocannon RWS was possible but would be more prone to damage because it would be outside its normal turret and more exposed. The solution to that was the 30mm autocannon on Stryker which operates like an RWS because the turret is not manned. The 30mm was long a proposed upgrade for the M2 tracked vehicle and the 30mm and 25mm weapons are both similar in design and from the same manufacturer. The 30mm autocannon RWS adds over a ton to the weight of the Stryker but the troops who received the 30mm ICM in 2017 found it a major improvement. The 30mm autocannon had a max range of 3,000 meters (more than twice that of the 12.7mm machine-gun) and was more accurate. It fired HE (high explosive) anti-personnel shells with the option of using armored piercing ones as well or shells HE with fuzes that produce air bursts.
While the U.S. was first to develop a unique wheeled armored vehicle like the Stryker it was late to do major upgrades its family of wheeled combat vehicles. China, which emulated Stryker, moved fast to upgrade and heavily arm its Stryker-like wheeled armored vehicles. China already had wheeled combat vehicles before Stryker. But noting the success of high-tech Stryker in Iraq, China made changes to its new ZBL 09 8x8 wheeled armored vehicle, which entered service in 2009. This 21 ton vehicle has a crew of three and carries 7-10 passengers. The ZBL 09 is actually a bit larger than the 7 meter long Stryker. At 8 meters (25 feet) long, three meters (9.2 feet) wide and 2.1 meters (6.5 feet, to the hull roof) high theZBL 9 is also heavier. Yet the ZBL 09 is amphibious and has a top water speed of 8 kilometers an hour. On roads, top speed is 100 kilometers an hour, and max road range on internal fuel is 800 kilometers. The infantry carrier version has a turret with a 30mm autocannon. There are also artillery versions carrying either a 105mm or 122mm howitzer. An export version was offered in 2011 as the VN1. The ZBL 09 was also based on Chinese experience with its smaller 13 ton 6x6 WZ551 that had entered service in 1995. Seeing what the Stryker could do the ZBL 09 was became more than just an enlarged WZ551. With the addition of many of the electronic systems found in Stryker China proceeded to try out many more electronic gadgets (not all of them worked) and more variant models. China has several medium brigades equipped with ZBL 09 and the VN1 has become a popular export item. The Chinese marines also use versions of the ZBL 09 and this vehicle is found in many other combat units besides the medium brigades.