first off, I don't think so, but you can never tell with rust. A picture of the top and bottom would help.
However I think the Read Shell was in the 7-8 lb range and you say yours weighs 11 lbs. Is there a sign of a fuse? or even a hole for one? Google Confederate Read Shell and you can see pictures. Not sure what you have, but it does not look like a Read to me.