Not a whole lot new under the sun when it comes to fragmenting bullets.

I wonder if anyone played with sub-calibre sabot slugs in those days.
They obviously didn't have the plastics we now do but they were also just as inventive as anyone else.
I have used those in my Beretta O/U and they can be very accurate (and deadly).
I had bought "paradox" rifled chokes for it but ended up not needing them.