While senior Army weapons developers welcome the possibility of longer-range accurate artillery fire, they also recognize that its effectiveness hinges upon continued development of sensor, fire control and target technology.
“Just because I can shoot farther, that does not mean I solve the issue. I have to acquire the right target. We want to be able to hit moving targets and targets obscured by uneven terrain,” the senior Army developer said.
Multi-domain warfare is also integral to the strategic impetus for the new ERCA weapon; longer range land weapons can naturally better enable air attack options.
My guess is that the range comes at the expense of rate of fire. So not all cannons would be replaced even if cost wasn't a factor.
Existing cannons will have their range extended to 40 kilometers with a new round.
And yeah, the range requires deep sensor capability to fully exploit deep in enemy territory unless the range is just to keep the American artillery farther behind the front line to avoid enemy counter-battery fire.
Oh, and I've mentioned the Air Force angle of long-range Army artillery.
The first article describes ERCA:
The service is now prototyping an Extended Range Cannon Artillery weapons with an improved tube, larger caliber round and new grooves to hang weights for gravity adjustments to the weapon – which is a modified M777A2 mobile howitzer.
This would be very useful. We used to have longer range tube artillery in addition to the 155mm guns during the Cold War, but cut back those in favor of the MLRS rockets to support one caliber of gun.
