I don't think that shell is constructed of oak.
Google some images of quarter & flat sawn oak.
The grain pattern, while figured and colored (stained?) somewhat like oak, does not resemble oak.
In addition, in the 2nd picture (profile pic without handle visible), you can see 2 repairs.
Both of these repairs are not cracks at the glue joint, but rather splits (or checks) in the staves.
Oak is a dense wood, and somewhat prone to checking from the end grain (splitting from the end of the board), but would it be very rare for it to check over the entire length of a stave as is evident in that repair.
Here's an
Oak Gon Bops Project recently on Ebay (auction is ended, so you'll have to scroll down the page to see item images).
Plenty of cracks at the gluelines. Couple of checks from the bottom endgrain, but none for full length of staves.
Compare the attributes of the grain patterns between the two shells, they are not the same.
Still a nice looking shell with interesting hardware.
Just don't think it is Oak.
JMHO