Great,thank y'all.
It is Vectan A0 from a Bornaghi 1oz factory trap round. Looking at various load data,everything makes sense.
Just analyzing here, I sometimes use factory trap rounds to make "Economy Slugs" by substituting the original shot with an appropriate slug. They make for mild loads,wads get toasted but they shoot good enough for short range practise. Fast,easy and cheap to make.