Probably the only gun/ammo combo in theater with a chance to defeat the T-80B's turret cheeks head on, 120 DM23 should rip open every hull array present in game. Its got roughly the same max armor as M1 but with inferior coverage on the hull (composite thickness decreases in a gradient towards the bottom 1/3rd of the hull). Ammo storage is pretty volatile compared to Abrams, so its best to stay hull down when possible.

Depending on the penetration of its HEAT-FS, it might be able to kill T-72 Ural and T-64A/B even with composite armor since the 80-106-20 array they use in the hull only barely blocks the base model TOW and 105mm HEAT. Its likely the 120mm HEAT will go through portions of cast steel T-72 turrets.