The M338 is a third generation, tungsten alloy and antiERA APFSDS for the IMI MG251 cannon used by the Merkava 3 and 4 series of tanks. It entered service around the same time DM53/63 did, however, in-game performs a bit worse than those despite similarities in muzzle velocity (L/44), penetrator mass and propellant weight+type.
Notice how M338 penetration matches DM53 (L/44) from 500m and onwards
For some reason M338 isn’t even listed on the chart with all APFSDS in-game: Характеристики APFSDS снарядов - Google Drive
Rheinmetall and IMI collaborated on the creation of M111 (licensed produced as DM23), M413 (licensed produced as DM33) and M426 (licensed produced as DM63) for the L7 cannon: such collaboration probably extended to the Rh120 L/44 too.
So…Is M338 underperforming?