But allowing the Panzer III to use APCR rounds would make the Panzer IV not worth building, and to be honest, CoH still needs some degree of realism with units, and having an army of Panzer III's in the battlefield instead of Panzer IV's seems a little silly to me.
But the message is settled, the Panzer III can NOT penetrate the frontal armour of a T34 (unless using APCR, but that would never happen IRL)
Who sais Ostheer will have a PzIV?
Becouse ACPR will be an ability that costs ammo PzIII will be inferior to PzIV.
Sure you can build an army of PzIII. You can build an army of Ostwinds too and it will gork well vs anything thats US, not from TierIV. But in the late game PzIII should be supporting unit to Stugs, Marders or JagdpanzerIVs. Becouse it was a little faster than PzIV it will be usefull at flanking. (like a short barreled sherman)
One more thing about AP shells. I know that they were rare in Germany but US produced only solid AP shells for their 57mm. All other types of ammo were made in UK and APCR or APDS rounds were never developed.