tank penetration and shattering

I have been mucking around with the ATRs trying to work out weak spots on the tanks (engine grills on the rear deck of the t-34 and the t-70 are great targets :p ) and have noticed that sometimes the round is playing the shatter effect but still doing damage, an example being shooting at the front tyres on the half-track spawning the shatter particles (and more importantly, going *ping*) but still doing damage to the wheels/tracks. Is this an intended feature? It feels a little counter-intuitive if there's no visible/audible difference between shatter-no-pen and shatter-penetrations unless it kills a crewman :(