Mark,
You forgot the HE rounds for the M1, and I think that they do have a WP round. I did a lot of testing on the M1 while I was at Ft. Knox from 1977 through 1980. I was the requested pilot (by the testing division) for flying the targeting exercises and firing exercises. I saw an M1 shoot eight rounds at eight different targets in less than 45 seconds while traveling over rough terrain, which included ditches, logs and other impediments. The tank hit 7 of the eight targets ranging from 250 meters to 4400 meters. The 250 meter target was the target that was missed. The sight paralax caused the round to impact the burm in front of the target (a turret sized siloette), caused a large spray of dirt and slowed the SABOT to were it was ineffective. I know because it was caught on film from the rear of my aircraft, I was hovering sideways about 20 feet above and 50 feet behind the moving tank. An amazing display of firepower. The cameramen and I had to coordinate each position with the crew so that the aircraft would be in the proper position to catch the shot along the gun-target line.
Huey