For a century, artillerymen have emphasized being able to fire a lot of shells quickly. But those shells are heavy and a mobile army cannot drag all that much weight along with it. Which brings us to the U.S. Army's much upgraded M-109 self propelled 155mm howitzer. It is now called the Paladin (M-109A6) and was introduced in 1992. The M109 series first entering service 40 years ago, the M109 was well designed and performed well. Firing up to four rounds a minute at ranges of up to 30 kilometers, the Paladins major problem is ammunition supply. For planning purposes, the Army has each Paladin firing an average of 205 shells (20 tons) a day. There is also the problem of keeping the Paladin supplied on a battlefield that will be covered from, time to time by enemy fire (machine-guns or artillery.) The solution here has been, since the early 1980s, the FAASV (Field Artillery Ammunition Supply Vehicle), which is the same chassis as the M-109, but the turret replaced with a box structure that holds 98 rounds of 155 ammunition. The FAASV is designed to link up with the rear of the Paladin, insert a conveyer belt and move 8 rounds of ammo (the shell, fuzes and propellant) a minute. The problem, again is, that there is only one FAASV per Paladin and the Paladin can fire all the ammo in a FAASV in less than 25 minutes. While the FAASV is designed to quickly  get ammo into the Paladin, it takes over an hour to load the FAASV from trucks (several kilometers to the rear.) A ten ton truck can carry about 110 rounds of 155mm ammo, with another 100 rounds in a trailer (which is not always possible if the trucks have to come in off road over rough ground.) Firing the gun is easier for the artillerymen than keeping the gun supplied with ammunition. A solution for that problems is more capable ammo. But this costs a lot more money. A plain old HE (high explosive) 155mm shell costs about $600. A "smart shell" (carrying anti-tank or anti-personnel bomblets) costs five to ten times as much. As cost effective as this approach is in combat, in peacetime, legislators don't like to pay for stockpiles of these more expensive shells. One solution would be to buy more cross-country trucks, with built in cranes (like the HEMTT) and train the artillery ammo handlers to rapidly get 155mm rounds off the trucks and into FAASVs, or the Paladins themselves. This may work, for no one will pay for an even more high tech gun (the cancelled Crusader) than the Paladin, or a large supply of fancy shells. So the artillerymen are just trying to do more with what they've got.