XM2001, XM1203 and now XM1299. It seems the need to one up other people can be quite a detriment. If they just went for a L52 gun without any extra frills it would be in service by now, it might not be better than K-9 but at least it would exist.
XM2001 was a victim of the peace dividend. The Army wanted it but with the Soviets out of business and the future forecast of wars being low intensity peace keeping the big 155mm 52 caliber gas turbine powered SPH was out. It died along with its new GT engine that was supposed to be a drop in upgrade for the Abrams.
It’s intended replacement?
XM1203 NLOS C. Which in a great power competition era wouldn’t have worked. NLOS C was part of the FCS family of manned vehicles it was supposed to be an automatic loading 25 ton, 155mm 38 caliber SPH.
Note that caliber because that means that it would still have come up on the short end of the range debate. Despite what a lot of media said of FCS it wasn’t meant for force on force applications it was meant for rapid deployment against poorly equipped forces particularly asymmetric in a show of force not use of force role. It was supposed to be backed by conventional armor if a great power competition came up.
So even if FCS had gone its course we would still be talking about something like the XM1299.
XM1299 was built on the suspension of the improved M109A7 155mm 39 caliber SPH. But it wasn’t just a long barrel A7. Atleast that wasn’t its end game.
It was also to be using an automatic loader originally developed for the XM1203. Though it would lack the magazine capacity of the K9A2 Thunder (roughly half) it offered much of the capabilities. Put a pin in this.
In 2023 BAE systems the Paladins manufacturer and Rhinemetall demonstrated an M109A7 with the L52 cannon from a German PzH2000. This isn’t actually the first time this has happened as far back as the 1990s mostly European militaries have looked into even done modifications to their M109 SPH with 47 and 52 caliber cannons.
So is this the end?
If you read carefully I just gave two potential upgrades to the M109A7. The 52 caliber gun and the automatic loader.
Alternatively the U.S. has been looking at wheeled SPH systems though I doubt that would be endgame as replacement for the M109A7. However the top options there are already 52 caliber guns. They have yet to move beyond just window shopping.
Finally AUSA shows have of late been attended by South Korea’s Hanwha defense with them even demonstrating that the lates K9A1 with US Army ammunition types and making no secret of their intentions for the American subsidiary of Hanwha to become an American military iron monger. Depending on how the XM30 rolls it may create an opening for an American Thunder variant in the later Half of the decade.