Bryan, please do not do anything remotely even resembling turning this over to anyone who wishes to destroy it or render it inert.
If this is your fuse well, the lighter colored impression on top of the piece in the picture, you have absolutely NOTHING to worry about.
The construction of this piece, if it is indeed a projectile, is simply that a wooden fuse adapter was inserted into that cavity with a powder chamber inside. The wooden fuse adapter is most likely long ago rotted away leaving only a dirt-packed hole.
It appears there is a curvature leading down into the fuse well. No real projectile I know of has this. It may not even be a shell.
But at any rate, you are not going to set the piece off by taking a screwdriver and cleaning the hole out. If you could detonate the projectile simply by digging into the dirt in the fuse well, imagine how many would have gone off at the firing of the cannon -- all of them.
These are not the dangerous monsters they are portrayed to be in the media and by many ninnies in museums and SWAT teams. (I can say these things as I work in the media and my friends are the GOOD Swat teams who won't steal your projectile saying they'd detonated it).
Bottom line, simply clean the cavity out. If you are still uncertain about this, I will do this for you. Seriously. This is the easiest of ALL projectiles to render inert.
Simply let me know if you want it cleaned out and I will do it free.
Richard