Panther had no Problems penetrating IS-2s frontarmour.
tarrif.net
Go german/soviet flag and then vehicles there are Penetration datas for all tanks:
Gun Penetration at 500m distance(choosing the best shell for all tanks):
Panther Gun Penetration : 174mm.
Tiger Gun Penetration : 155mm.
IS-2 Gun Penetration : 147mm.
ISU-152 Gun Penetration : 124mm.
SU-100 Gun Penetration : 167mm.
Jagdpanther / King Tiger / Elephant Gun Penetration : 217mm.
Panzer IV Gun Penetration : 108mm.
T-34 Gun Penetration : 64mm.
T-34/85 Gun Penetration : 107mm.
Don´t even try it. I already showed UGBEAR another source that the Panther could defeat IS-2s frontally on about 1km. He even asked for that source but then seems to ignore it anyways. Maybe it doesn´t fit his image of Russian super tanks.
As for the 40:1 statement. You are comparing a medium tank with a Heavy tank. Of course the numbers are different there. Better compare the 50k T-34s to the 5,7k Panzer IIIs, 10k StuGs, 6k Panthers, 9k Panzer IVs rather than 1350 Tiger I. A proper comparison would be IS-2 versus Tiger I , which is roughly 3:1.
A direct comparison is hard anyways as Russians mostly relied on the T-34 as their main tank while Germans had more different types as their "main" armor. Still a huge numerical advantage for soviets but not 40:1.
As for the uselessness of the statement: I´m sorry you can´t see a scheme in the game. It´s not that hard.
Last but not least: Why are you talking about an IS-2M, UGBEAR? Someone with your knowledge about tanks should know that it was in fact a version of the IS-2s deployed in the 1950ies.