Mike, I examined your Read when Carl had it at the Richmond Show. I am certain that it was one of 240 made by the Augusta Arsenal in late 1863. These were the first 3 inch Rifle shells ever made by Augusta. They clearly screwed up. But they had permission from Richmond (letter March 1863) to go their own way with projectile designs. If I am correct, your Read should have a star or segmented interior. All of Augusta's field-caliber shells did except their 10pdr. Parrotts. Also, all of Augusta's projectiles were sent to the field fixed. Is their any trace of twine in the "lubricating ring." That's what Augusta called their "safety groove." Half (120) of Augusta's 3 inch Rifle shells were forwarded to the Army of Tennessee. There must be examples or shrapnel from North GA.
Look closely at the January 1864 letter below. It was written by Col. Olandowski, Ordnance Chief of the Army of Tennessee, to Col Gorgas in Richmond. Olandowski had just witnessed the artillery experiments in Augusta. The same ones seen in the previous posting. He noted: "The shells with copper cups [i.e. 3 inch Reads], having holes cut in their sides to communicate fire to paper fuzes, do not fly as regularly as those having thicker cup and no cutting in them." Olandowski continued on to suggest the sabot pictured below with three holes in the top. I believe this new sabot design was excellent but ignored by Col. Broun in Richmond as he had already developed the round-nose Broun 3 inch shells. In the Deep South, they continued to make Reads.