I was playing around with the m60 the other day and noticed that I could penetrate and knock out m113 apc using only the 7.62 mm MG provided that I fired from close range of about 75 m or less. From this distance I was able to penetrate the side plate of this APC which is 44 mm thick according to the encyclopedia, way higher than the 7 mm that the 7.62 mm can go through. Checking wikepedia I read that the m113's armour was designed to protect from 7.62 mm rounds, but was in practice too thin to protect from this threat at close ranges; it seems the armour model in game is consistent with reality. My question is why the encyclopedia is so far off with regards to the protective capability of the M 113 armour; perhaps it doesn't account for material type (m 113 has alluminum armour) or something like that.
The encyclopedia is indicated only the thickness of the armor, but does not specify its parameters (which are used in the game for calculations). Therefore encyclopedia - is a rough estimate and not an exact. Especially for such exceptions like in aluminum armor.