It appears your two Read-Parrotts were made about two years apart. I'm only just now learning about your wood fuzed Atlanta Read-Parrott, but I have been studying that side-loader pattern for some time. It is not a common Virginia pattern. They are primarily found around Fredericksburg, Chancellorsville and the Rappahannock River Fords. I believe it was a style made by Tredegar primarily during the second half of 1862. A new official design had been prescribed by the Richmond Arsenal during the summer of 1862 (see the last page below) and Samson & Pae made an exact copy of that improved design which replaced the smooth-sided Read-Parrott. S&P had the most skilled workforce of any of the Richmond foundries. Many trained Europeans. When Cmdr. Brooke wanted a difficult new pattern made like the mill-based bolt, he turned to Samson & Pae. The first three shells below were Tredegar's version of this new "sleeved" pattern. It has the same indented base but they didn't bother to reduce the nose as S & P did. The first of this style were probably made in August 1862. That corresponds with Tredegar's production of its last 3 inch Rifle shells - the flush-bolt Mullanes with copper fuze plugs. Tredegar would soon halt production of 10 pounder Read-Parrotts which helps explain their rarity. The day before Pete George dug seven of the rarest side-loaders including several of this pattern at Bank's Ford, I dug one with a recessed bottom and a wood fuze plug which shows the switch to this new design predated the use of copper fuze plugs during the summer of 1862. Note that one of the side-loaders below has the flange of its fuze set into the shell body. That reinforces the dating of this pattern because it is obvious that practice to seat the McEvoy fuze igniter lasted only a couple of weeks during late 1862. We know this from the similarly fuzed Reads.
I could be wrong with my attribution but I'm fairly certain Tredegar was responsible for the first three shell seen below. Why?
1) No lathe key. [dog, knob, or whatever] On all the shells, big and small, that I have reason to believe Tredegar made, I have never seen a lathe key on the ogive. No key slots in their cone-shaped mandrells. This includes about 20,000 3 inch Archers, 4,000 3.35 Archers for the rifled 4 pounders, 13,000 Mullanes and the Bormann-fuzed 10 pounders from early war sites.
2) The quality of the wrought iron sabots is very good. Tredegar had the best rolling mill in the South. The competing foundries usually had to hammer their iron into shape. Tredegar did not share.
3) It is obvious that these first three shells have swedged sabots. It would make sense for Tredegar to be the first to employ that superior method. Look at the final S & P shell below for an example of the hammered and hand-punched sabot. Sometime in early 1863, the other foundries adopted the swedging technique. This is backed up by documents and excavated examples. By that time, Tredegar had completely stopped the production of 10 pounders and they made no more for the Army for the remainder of the war.
I will have more to say about your other Read-Parrott.