You can't remove the bolt w/the shell stuck to the bolt face with out removing the ejector from the gun.
A couple of things about the gun first,,
With the bolt in the open/handle up position AND the bolt is still assembled in the gun,,the striker-firing pin can not hit the primer. Believe it or not it has the same spline allaignment type safety between the striker and bolt head that the 98 Mauser uses.
The trigger/sear is also the bolt stop.
You are smart in not taking a cavalier attitude in handling this. It is a live round under a cocked striker. Some people would not be as wary and 'accidents' have occured.
Take the barrel-action right out of the stock.
On the bottom of the stock just forward of the magazine well is a large dia slotted screw. Unscrew that and the entire assembly separates from the stock.
A quarter works well in the overly large slot in the screw.
On the under side on the action at about the 8 oclock position just in back of the mag well is the ejector. A stamped steel part attached with a screw (maybe two?). The arm of the ejector fits up into a slot thru the tubular action and into the bolt raceway.
That arm is what hits the edge of the case as it's drawn back on the bolt kicking it/ejecting it from the gun.
You can't get the bolt w/stuck case past that w/o removing it.
You can also remove the magazine guide & latch spring from the bottom of the frame. It's large headed screw may be going on thru and interfering with the bolt movement passed it's point w/a shell in place.
Once removed, the bolt can be taken out of the gun by pulling the trigger rearward and pulling the entire bolt assembly out of the action.
See if it doesn't come out of the gun at that point.
The striker is cocked and held there by a 1/8d pin through the striker head at the rear of the bolt. That pin can be seen at about the 8 oclock position sitting in a detent notch in the bolt body. The bolt body under that notch is cut away at an angle towards the front of the bolt. That slanted surface is the cocking cam,,cocks on opening.
**The bolt is cocked and held there by the pin sitting in that detent notch when the bolt is in the unlocked/open position. **
The extractor on the bolt head is a U shaped spring steel afair. It has 2 arms extending from it.
The one extractor hook you can see easily plus another directly opposite it w/less of a hook on it. That opposite side acts as both a partial extractor and more as a shell guide for loading and extraction.
That spring steel clip unit is easily damaged so take it easy on it.
What you want to do now is pull the bolt out of the gun with the shell attached. It may give some resistance but with the trigger pulled (sear out of the way) and the ejector removed, it should come out the back of the gun.
Once out,,handle it carefully as it's still a cocked mechanism.
If the shell does not easily come off the bolt face at this point, remove the front bolt head w/shell from the bolt assembly.
Take the front rotating bolt head portion of the bolt with the shot shell attached and give it a 1/2 turn either direction and pull that right off of the bolt assembly itself.
That leaves you with just a stripped bolt head w/extractor and the shell stuck to it.
Left behind is the rear bolt body w/ bolt handle, striker, firing pin, main spring.
Now you can better see what is holding things together and without the cocked mechanism being attached to it.
If you just pull the case off the bolt face, do it in the direction it would normally be kicked out of the gun in operation. That will lessen most any possible damage to the fragile part. Pulling it up or down off the face can bend the part or tear it right off the bolt head.
If you find that you've somehow 'uncocked' the bolt when you go to put things back together (it will only go back in if it is cocked),,,an easy way to recock the bolt assembly is to place it into the gun backwards with the 1/8"d pin I mentioned in the slot in the left side of the frame and lift the bolt handle up.
It'll cock the bolt for you quick and easy.
Better than trying to fight the powerful mainspring and headless striker w/ screwdrivers & pliers in a vise.
Works on some other bolt shotguns and 22 rifles too (Marlin).
Sorry for the long post,,hope this helps out.