The T-34-85 had, as the name implies, an 85 mm gun, perfect size for KO'ing a heavy tank like the Pz VI Ausf. B Tiger II (König Tiger), the American 76 mm and 90 mm guns and the British 17 pounders were also Tiger killers
I swear the lack of a stabiliser is the only thing keeping the Firefly at a lower BR than the other 76mm Shermans(other than the 76 jumbo) in WT, given the max pen of 190mm. Oh, and it having less frontal hull armour for seemingly no reason, like with most other British and French Shermans