I was reading a book a while back and it talked about how in a major battle, the Americans were firing so many shots so fast that the Germans believed a fully automatic howitzer had been created. It got me thinking as to why we didn’t have any. Would single shot batteries be cheaper and easier? Anyways thanks for the help.
Current US Field Artillery officer with a degree in history here. My knowledge is limited to the US and its arsenal of field artillery, but I feel I can give this a shot.
We still don’t have a “fully automatic” howitzer for a multitude of reasons. The closest we have come have been autoloaders, which vary from simply loading and ramming a shell into the tube to completing the whole process of charge selection, shell selection, and setting the shell’s fuze.
1)The relative complexities of the aforementioned tasks form a barrier to fully automatic howitzers. An The strength of howitzers are in their ability to shoot far and deliver fires highly specific to a target for relatively cheap (when compared to aircraft). The relative weight and mechanical complexity of an all in one system has, until now, been prohibitive towards the development of a fully automatic gun. Other countries outside of the US have adopted autoloaders since the first began appearing around WW2. But the nature of separate loading (where powder and shell are loaded separately) ammunition has more or less negated the benefits of an autoloader outside of manning requirements.
Artillery is more than just pointing and shooting. Factors such as the tube temperature, tube wear, and residue left behind by firing multiple rounds in succession can have drastic impacts on accuracy if not properly corrected for. In WW2, many factors were corrected for, but even then rounds could be off target. Improvements in manufacturing of rounds and propellant as well as more accurate meteorological techniques have lead to more predictable outcomes, but there is still an expected probable error in a shell’s path from the tube to the target. Fully automatic fire can shift the gun and cause it to heat rapidly, compounding these variables and leading to a decrease in accuracy.
Counter-Battery fire, then and now, is a very real danger. The risk of losing a gun to the enemy artillery can be detrimental to a unit’s ability to complete their mission. A fully automatic gun creates a large signature on sonar, allowing the sound of the gun firing to lead the enemy to its position. It also allows anti-mortar and artillery radar to collect more data from the rounds fired to accurately estimate the howitzer’s position. It is less risky to simply use more guns spread across an area to hit a target with a similar amount of shells.
Mortars more readily fulfill the quick, some what accurate fires that a fully automatic gun would be ideal for. They are much cheaper. The M120 120mm mortar only costs about $20,000 compared to a M119 105mm howitzer with all its upgrades is north of 2.5 million. Mortars are also much more mobile. The smallest 60mm mortars are completely man portable and can be shot from a knee. The larger calibers are often vehicle mounted with little difficulty or transported disassembled by the mortar section to whom the tube is assigned. Even better, the larger calibers have decent ranges that overlap nicely with the lower caliber howitzers. This is by design and allows an echelonment of fires at a variety of ranges. At extreme ranges, the rockets take over. The M270 MLRS can hold 12 rockets and fire them all consecutively. Reloading the rocket pods takes some time, but the amount of firepower one can put down in such a short period of time is tremendous.
However, despite those reasons, there is a current shift towards adopting more mechanized artillery systems. Some countries already have. The US and a few of her allies are slightly behind in that regard. For example, from its release in 2005 many nations adopted the M777; a towed, manual gun. A self propelled gun ( usually a gun on tracks, but sometimes on a wheeled base) coupled with an autoloading system addresses many issues that have previously given much higher rates of fire significant tradeoffs. These self propelled platforms existed in WW2, but suffered from reliability issues and often lacked autoloaders. Coupling these two advancements together has been a long time coming for the United States. Many have had the same thought you have, but it takes time for technology to mature and the perception of need to meet and create a new platform. In the meantime, systems have been put in place and battle tested. Ultimately these systems were found to be effective and advancing towards a fully automatic gun was not deemed necessary. As the US reassesses its capabilities, it has now become a priority to fully modernize the field artillery.
This combination of self propelled, autoloading guns is likely the closest we’ll get to a “fully automatic” gun. The reality is that there is no real need yet for a howitzer to shoot at something insane like 200 rounds per minute. The forces upon that gun would be immense and I doubt engineers could find a sufficiently accurate and portable solution cable of such a volume of fire.