IMO penetrators with 1000+ pen doesn't really help much at the moment... Unless your opponent is Leo II lol. Slapping a 140 onto 4th gen was the idea of PLA in the 90s while the (former) Soviet tank programs still had momentum, and in that time PLA did indeed try to put a 140/135mm onto a tank, but that need soon diminished after realizing that a true 4th gen of the 21st century doesn't only need statistical specs, but a lot of other auxillary abilities and advantages, and needs to be more integrated with the whole ground-air system. Strategic needs are also now no longer inferior to tactical needs for a tank, that's why we always thought weight reduction so important since the idea of a third-gen. I quote the words of Chief Designer of 99, 祝榆生, a well respected researcher: "系统取胜，功能覆盖，新技术先敌应用", rough translation: Win by system, have a wide coverage of functions and use new technologies before the enemy does." That's the systematic battle I've always been talking about, and as you can see from the quote tanks are not designated for some certain function like ATGMs are, they're simply weapons designed to accomplish and assist ground-based assault attacks, along with IFVs. And we also use new technologies to our advantage, which allows for more choices for development in the future. And BTW Mach 6 penetrators are actually not as efficient as the ones with same kinetic energy at 1600~1800mps... Because the higher speed doesn't really penetrate more than the slower one and the penetration dynamics would be more associated with fluid dynamics, and therefore we can't use structural design to our advantage... (Penetration of very high velocity solids can be seen as a fluid so therefore penetration only relevant with solid density) And PLA isn't interested in DU, we don't have so many nuclear waste and we have 60% of the world's Tungsten AND we have the technology to make self-sharpening W penetrators (already used in various munitions) ... There's also no 155mm gun in the world thatt can fire armor piercing rounds, what I talked about was using 155mm HE to anti-tank...
For penetrators, there's a material velocity at which the penetrator is most efficient relative to energy. DU is relatively low, Tungsten is higher, but once you get over that velocity you see diminishing returns.
