Hello,
I think the answer may be a little simpler than shipment. I believe them to be squared off by an explosion of an ammunition dump like the one at Synders Bluff north of Vicksburg.
The CSA used alot of singular 69-caliber round ball cartridges without buck & ball as well as buck & ball and the explosions could have suared them as easily as it did Enfields & 3-groove minies.
The Tyler arsenal records states many such cartridges were made.
Tom Stelma