The best thing to do would be to remove the broken case from the chamber. You might try driving a soft lead slug down the barrel to see if that will dislodge it. Otherwise a trip to a gunsmith would be in order. ...
Another idea is to invest in some carrasafe - very low melt alloy, various types melt between abot 150 deg F and 200 deg F.
Oil up the bore & everything, block the
chamber & Bore with a bit of
crap paper towel, pour "a bit" of the cerrasafe
down the bore From the Chamber side!and let it solidify,
then drive the whole mess out.
from the Bore !Legal Caveats:
YMMV,
I'm not forcing you to do it,
I said it's "an idea",
not my fault if you screw it up
I really don't care what you do with your stuff anyway....
good luck
( it's all a joke , son, a joke - Foghorn Leghorn ca 1963 )
prf mvl
reason for edit -
I've gone stoopid today.
check with someone else before following my directions
don't kill yourself or ruin your toys on my advice...