Lead castings are slightly less than theoretical density.
The one and only accurate table of weight vs dia was developed by George Schalk, Pottsville, Pennsylvania, 1824 - 1892
It is reprinted in The Kentucky Rifle Captain. John G.W. Dillin, 1924
I copied it for my book Michigan Gunsmiths
If you shoot these things you must read Dillin. If you only own one gun book, let it be Dillin's.
By the way, Mr Schalk says a .519 ball weighs 34 to the pound (206 grains)and a .530 ball 32 the pound (219gr)
Get thee a copy of Dillin, he gives actual real information about rifles
(leave the math to your professor).