June 29, 2016:
The Italian firm that introduced the 24 ton Centauro B-1 8 x 8 tank destroyer in 1991 just introduced Centauro 2, which is heavier (at 32 tons) than the B-1 and armed with a 120mm gun instead of the 105mm one. The Centauro 2 also has upgraded engines, electronics, fire control and armor protection. The B-1 was the anti-tank version of the Centauro family of 8x8 armored vehicles. The U.S. Army leased 15 Centauros for testing while it was developing its Stryker series of vehicles. There was even a 21 ton tank destroyer version of Stryker armed with a 105mm gun. The Italian Army has already ordered 136 Centauro 2s.
In 2006 U.S. Army received the first of 142 MGS (Mobile Gun System) vehicles. These were very similar to the Centauro B-1 and were Stryker wheeled armored vehicles with a special turret that mounted a 105mm gun. There are two machine-guns (7.62mm and 12.7mm). The 12.7mm machine-gun is controlled from inside the vehicle. The 105mm gun is a modified version of the one used on the M-60 series of tanks. This gun has an autoloader, and carries 18 rounds of ammo. There is anti-tank and anti-personnel ammo available
There were to be three MGS assigned to each infantry company. In effect, the MGS was a return of the assault gun, a turretless tank developed during World War II for infantry support. After World War II, the assault gun was dropped by most armies, to be replaced by tanks or self-propelled artillery. But that has not worked out as well as the assault gun, because during World War II, the assault gun was considered an infantry weapon, and "belonged" to the infantry. The MGS "belongs" to the infantry company it is a part of, will train regularly with the infantry, and thus be a lot more useful to the infantry. The MGS had a lot of development problems, and is over a year late. The 105mm gun makes a whole lot of noise (bad for any nearby infantry), and initially caused lots of vibration problems inside the MGS when the gun was fired. The MGS contains a lot of electronics, and a very capable fire control system. MGS gunners regularly put 105mm shells through window size targets at 1,000 meters or more.
Production of the MGS ceased in 2012. The unofficial (and real) reason was that the increasing available of smart munitions (especially GPS guided artillery shells and rockets) made the assault gun much less useful. But not for everyone. Nations that don’t use the expensive smart munitions as much as the United States are finding the wheeled assault guns like MGS or Centauro a cost-effective weapon.