Shermans? Bazookas? 
You can't just let go almost dead King Tiger or Tiger Ace and suff like that because when it backs it can be GG for you. You made great ambush but somehow KT escaped with 1/10hp. Next time OKW player won't let you for that. That's the problem. Lack of "chasing" units.
well, i'd say its more of a problem with super heavies in this game having ridunculous armour and health.
ill assume you are talking about 2v2+ because you are talking about KT which is rare in 1v1 i believe.
use your soviet teammates to finish it off or chase it with jackson and shermans.
the matter of fact is that jackson reloads slow and has low health. there is just too much risk chasing just to see your jackson miss/shell bounce. just the way it is. it is frustrating but i don't know if that means if jackson is up or op.