hi John, i will try and answer those details
1 yes the sabot is warped, but the condition and lack of fuse( it is a screw in fuse) , and no rifling present, leads me to believe this is a drop, maybe because someone hit it or they threw it off to the side because the sabot is warped. I believe the former because there is a 1/8 x 2" linear mark along the top edge of the sabot anout a 1/8" in. if it was done prior to firing, it wouldn't have worked at well . I see no practical way for it to have happened after fireing, but its possible.
unless it was field modified, like with a hammer and dull chisel, to allow a flame gap, by just making one side not fit as tight, but thats a really long shot idea.
2.unfortunatley( and jealously) I can't do picture like you can, but will try and descibe the sabot. If I have to, I can draw and scan a picture, but it would be a line drawing
To start with we have a one piece wood cylinder 2" in diameter and 1" long
when turned, I see 4 extra steps which would absolutely be unneeded to just hold the sabot flat during firing
1/2" from the top, we have included a approx 30 degree taper, reducing the diameter a little over 1/4"
The shadow you saw (thinking 2 piece)is a straight cut, going into and reducing the diameter another 1/8".
1/8" down, there is a groove all the way around, indicating the groove which was turned into it to be 1/8" x 1/8"
below that, for the remaining 1/4", the sabot then gains diameter again, my best guess is to the diameter at the bottom of the taper. because of the damage, I can tell you the largets remaining piece sticks up 1/8"
I thought the diagram would help, to took the time to include. precise measurements would maybe vary, but these are close
note: 98% of that bottom area are missing, but two points still stick up, so I'm sure of what I drew, but the bottom could have had a reverse 30 degree taper to the one shown, and returned to the original diameter for symetry
Hope this clarifies, and John if you wanted to post some your magic, I'll confirm what you drew till its what I can see, because your drawings are much better than mine
Additional note: the bolt has a lathe divot in it, indicating that possibly some lathe work was done AFTER sabot assembly, unless the collar on the bolt was the part turned. this type shell took alot of work compaied to other types