A few years ago I was in search of a 12 gauge slug to use in a Army & Navy Jungle Gun, the bores were ,729. H&H Paradox slugs had a cauton that they were not to be used in a bore size less than .735, so they were ruled out.
I found the S&B 12gauge 2 , they were just what I was looking for, but sorry, they were not available in the USA.
I found the Jungle Gun a new home and I will pass this informationon to him.