smokey truck, my 52 chassis took 400 lb. My chassis was in pretty bad shape. Not long ago I used 600 lb on one that was worst than mine!
Did you buy black sand....or was it Black Diamond from TSC. Around here the Black Diamond from Tractor supply is 8.50 a bag.... I can buy the fine sand for 3.28 a bag and its true blasting sand and has been sized to flow good. I get it at the concrete/mixing place.