Hello,
Yes, it's a little bit confusing if you aren't familiar with the area. The shell is a 12 lber Bormann with acutally weights about 8 pounds if a common shell (and 11 if a case shot). The 12 pounder designation is for a solid shot. The 24 gun battery is a battery of 24 guns located outside Marietta, GA that fired on Big Kennesaw Mountain, Little Kennesaw Mountain, and principly the saddle ridge betweent the two. It was a mixture of smooth bores and rifled cannon. A great many shells have been found behind the mountains over the years and recently with a subdivision developed in the main impact area a good many more were found. My son found his first shell, a 3-inch Hotchkiss, there. The gun emplacements are on Kennesaw Mountain Battlefield Park and are still in pretty good condition and make for a nice walk for the artillery lover.