Scott, as a matter of fact I did, and I should have mentioned that in my post. The tables are an excellent first point of reference for ID - thanks for raising that question.
The diameter and weight, while close to a 4 pound solid, are off enough that I have some doubt that it is a four pounder (although there was at least one documented four pound cannon in the area). Biggest difference is the weight - this one is a few ounces heavier than the weight listed in the tables. Spec wise, it is very close to a grape from a 42 pound stand - but for the life of me, I can't figure out why a 42 pound grape would be east of Vicksburg. I can't discern a mold seam either.
So, I guess what I am really asking is given the dimensions are close to a 4 pound solid, does anyone feel this is what it is?