ORIGINAL: James B
Did you check and make sure the barrel was clear of obstructions before you fired it? That would be a likely cause if it was not an overload.
IF an obstruction is in the bore, the bulge or burst (and of the barrel, not the case!) takes place at the spot where the obstruction was when the bullet hit it. A boreobstruction does NOT cause the base of the case to blow out, it destroys the bore......