I talked to a rep from Sumiko (distributer of VA) who highly recommended that I do not use lead shot, and just use sand. I do not know about "steel fill", but I would contact someone at Sumiko before you filled the chamber. My Mozarts used approximately 20-22 lbs. of sound. If you use sand, playground sand is what is recommended, and it MUST be dry. I was too impatient for the sand to naturally dry, so I ran many large pans full through my oven. It took a couple of hours, but I slept easier at night.
