heres one to scratch your head on. my son is in the pinewood derby thing, those wooden little cars, anyway the car can only weigh 200 grams, I was going to use 490 round balls I made for my 50 cal.. thing is how many grains(490gr) is there in a gram. I'm going to drill hole in the wood to put balls in what I need to know is how many balls to add. bottom line is how many grams does a 490 round ball weigh?