The 19th Georgia Regiment would have been typical of other infantry commands raised in this state, not "heavy" in any sense of the word.

Here are definitions of light and heavy infantry from a good source.
http://www.statemaster.com/encyclopedia/Light-infantry

By the mid-nineteenth century, distinctions between light and heavy infantry as employed during the Napoleonic Wars had been lost. Even as far back as the colonial wars, I'm not at all sure that any American military formation could reasonably be described as "heavy infantry."