The problem is semantics...
Armour is that tanks or does it include APCs and the like, what about half tracks like of WW2 vintage...
Tanks, is that the main battle version, Leopard, Abrams, Centurion only or does that include the likes of the M2 or M3 Bradley or the Lynx and other similarly equipped armoured Command and Reconnaissance (gun) Carriers...
Armoured Cars does that only mean the money transfer type of vehicle or what about the M59 or M113 troop carriers or the LVCTC7 or M1068 Armoured Support Vehicles...Hell, does it include a properly set up Humvee or Rolls Royce Phantom...
7.62x39mm AP will penetrate some of them because they are only lightly armoured so in fact he wasn't talking through his ass...
As to someone saying x39 instead of x51 or the other way round, once or twice, is an error, a faux pas, not a major catastrophe...if he continues to do so then he is mixed up...
As to ME109s or Fokker Wolfes in the pacific during WW2 is not far fetched as Germany sent a number of their planes to the Japanese, primarily for testing and possible acceptance by the Nippon War Ministry to accept them as an addition to the Zero and other models...Germany needed oil and Japan had captured some fields...