Originally posted by Staga 23mm VYa (Volkov-Yartzev) wasn't a wonder weapon; it penetrated 30mm at 100m and 25mm at 400m (angle not known).Later cannons used in Il-2, 37mm NS-37 (Nudelman-Suranov), penetrated 48mm at 500m distance at 90degr. angle.PzIV Ausf.H had 50-80mm armor at front but only 30mm at sides and turret rear and 20mm armor at rear superstructure and hull.So at good angle 23mm should be able to penetrate sides and rear of the PzIV."Ostwind" had its turret made of 25mm armour plates btw.
