This is why you are biased.
JP4 wasn't counter of heavy tanks. there are rather options; Panther.
so anyway if you want, I make calculations for you.
IS-2 Hit point = 1040
IS-2 Front armor = 375
IS-2 Target size penalty = 2600%
Damage of JP4 = 160
number of penetrated rounds to destroy = 1040/160 = 7
JP4 Hit chance to IS-2 at maximum range = 4% * 26 = 100%
JP4 reload speed = 4.3~5.2
JP4 Penetration at maximum range = 170
Penetration chance to JP4 -> IS-2 = 170/375 = 45.3%
Expected Time to kill IS-2 = 4.3~5.2 / 0.453 * 7 = 66.4s~80.4s
KT Hit point = 1280
KT Front armor = 375
KT Target size penalty = 2400%
Damge of FF = 200
number of penetrated rounds to destroy = 1280/200 = 7
FF Hit chance to KT at maximum range = 4.4% * 24 = 100%
FF reload speed = 8
FF Penetration at maximum range = 210
Penetration chance to FF -> KT = 210/375 = 56.0%
Expected Time to kill KT = 8 / 0.56 * 7 = 100s
JP4 can kills IS-2 faster than FF kills KT
Now admit that you are biased.
sorry.i mean the jackson vs kt..what we all talked about the last posts.....not the ff