Looks kinda cool but from looking over the site, I bet it is not very historicaly acurate.
Unless the web guys are not really part of the team.
like this from the Panzer 4 description...
The longer barrel proved itself primarily during the Russian campaign. As before, the Russian tanks seemed to be immune against the smaller cannons of the Germans - the F2 changed this drastically. Still, the Russian 'Panzer Rifles' were a big threat to the side armor of the Panzer IV. Subsequently, armor skirts were added to protect the drives and turret.
This upgrade turned out to be amazingly resistant against hollow point ammunition.