I’m gonna try to make a list of the issues that the M1 alone has, as it’s the one I’m most familiar with. Note that I’m compiling all issues with all variants into this list, but I will specify some vehicles. Here we go:
Turret ring armor is not volumetric
Turret ring is notably missing a large amount of armor, which should be around 250-300 area
The turret is raised too far off the chassis, giving it a easier to hit weak spot than should
ARAT 1 (M19) is underperforming against both kinetic and chemical threats
The composite armor array on DU M1’s is less effective than RHA, even for chemical threats
The engine is both too loud and should have directional sound, I.E., very hard to hear from the front, louder from the rear
The exhaust should be smokeless
The M1A2 SEPv2 can not remove the TUSK package
The M1A2 SEPv2 can not mount the trophy active protection system.
The M1A2 SEPv2 is missing the M829A3 cartridge.
The M1 (Early) is missing M833
The M240C coaxes on all M1s should have access to all 10,000 rounds without reload
The M1A2 SEP should be able to remove the mine protection package from the TUSK package
The bulkheads on the fuel tanks do not cover the top of the fuel tank, so the upper front plate is missing an inch of armor on some places
The hydraulic drive is mounted next to the engine, not next to the loader
(This one is obvious) When a blowout panel is hit while carrying the M830A1 round, it should not cause the round in the gun to disappear and cause the loader to load a round of M830A1, even if sabot is already in
(Small one, but bugs me) The IPM1 should be renamed to M1IP
M1s carry extra smoke grenades in the boxes next to the launchers
The orientation of the loader’s weapon station should be moved so that it can realistically be fired from the hatch, as well as have better traverse
M1s should still be able to traverse the turret if the hydraulic pump is out, just at a slower rate using the manual drive
The engine deck should not be ricocheting APFSDS into the turret bustle and detonating ammo after the round penetrates the entire turret
This is just what I remember off the top of my head. There very much could be more.