The Panzer has an armor leak which is contributing to it's vulnerabality at present, the leak is around the turet ring.
The best way to atack Panzers is from dead six at abot 45 degrease to vertical at about 500 yards a good one second bust into their engine deck will kill their engine, I have used P40's to do this before. The 50cal is extreamly effective aganst The Panzer, and the Osty, whay out of context to it's historical use in this role, to say it is uber would be puting it midely.
I see people who are prety clueless atacking tanks form the front and sides repeadely all the time, typicaly all that will ocure is that u track the Panzer, for consistant results use the above aproach and get close, this mimises ammo usage and maximises effect. once u smoke their engine/gun and they die spawn u will get the kill.
It is also possable to acheave an outright kill with the 50 cal aganst Panzers from a similar angle it hapens sometiems but not to often.
When on the ground 50cal MG's are extrodanarly effective aganst the Panzer from all angles, I have had M3's kill my main armorment on the panzer with short bursts before, this may be do to the armor leak howeaver, and that is being adreased in the next update.
50cal's can also smoke the Panzer engie from ground mounts easly from dead 6 at any range they hit them at, also compleat BS, but it makes the 50 cal prety handy.
I suspect much of this has been looked at for 1.11 though, err I realy hope it has.