Don, are you pouring into a vertical ingot mold, or a trough
(horizontal) style ingot mold? Also, what kind of crucible pouring
device are you using?
If you are using a WHIP, with a pouring dish, you will have an
easier time pouring accurately into the ingot mold, especially if you
are pouring into the top of a vertical mold. Be sure to rest the
crucible against the top of the ingot mold as you pour your metal,
and you should be pretty stable while doing so.
Those open-style trough molds are damn hard to make a consistent
thickness ingot with, but the vertical style molds use gravity to
help compact the shape into the mold.
Good luck, and wear safety glasses!!