VCM editor cylinder volume off

I've been practicing tuning using a GM 4.3 in a 2004 Chevy Blazer nice little guinea pig but I just noticed something an engine under general cylinder volume does not quite add up to the 4.3L 262Cu-in. if you do the math the cylinder volume is smaller by 0.36% so if you add a 43.5102cu-in X 6 = 261.0612 cu-in but if you do the math and divide 262 cu-in by 6 you get 43.6666 per cylinder volume. my question is is this the vcm editor interpreting the data from the PCM wrong, or did GM just make the cylinder volume smaller to correct any mistakes in the manufacturing for these engines.

Mod Kill this thread wrong area.