Using standard 55 gallon barrel size of 22.5 inches (1.875') in diameter  and  33.5 inches (2.7916667') high.

http://www.farmnetservices.com/calc/round_form.php?CF=0.8&commodity=ShellCorn&mm=b&tw=56.0

6.09 @ 55.0 lb test weight.
6.14 @ 55.5 lb test weight.
6.19 @ 55.0 lb test weight.
6.23 @ 55.5 lb test weight.
6.28 @ 56.0 lb test weight.
6.33 @ 56.5 lb test weight.
6.37 @ 57.0 lb test weight.
6.42 @ 57.5 lb test weight.
6.47 @ 58.0 lb test weight.
6.51 @ 58.5 lb test weight.
6.56 @ 59.0 lb test weight.
6.60 @ 59.5 lb test weight.
6.65 @ 60.0 lb test weight.