Bill, please use a digital Caliper to provide precise measurement of your mystery-bullet's diameter at the widest area. Additional photos would be helpful too.
Does it have a flat solid base, or is there a cavity in the base?
It does not match the profile of a Hanoverian/Saxon bullet, although it does "resemble" one. See the McKee-&-Mason civil war bullets book, page 26, bullet #63 for the actual Hanoverian/Saxon bullet. Another bullet shown in that book as bullet #74 is quite similar to yours... but that book says it is a .54 Maynard, and there was no civil war era .54 Maynard Rifle.
Precise diameter measurement, in hundredths-of-an-inch, is needed for narrowing down the possibilities for your bullet's ID.