31 grams = 478.403 grains. Just so ya knew. You were pretty close. LOL
I am enjoying following along with you as you do this project. The pictures are a very big help also.
I was telling a friend of mine about it just today. He thought it was quite innovative also.
Looking forward to seeing more as you go along! I really want to try this myself, sometime. Just for the fun of it. I am going to show this to my 2 sons & see if they would like to help.
Thanks again for sharing! & G'luck!