yes I believe Baker referenced forsyth shells in his writings, I think he used the term at least once in connection with his 4 bore loads too.

I just managed to track down the descendants of Samuel Baker and also a current pic of the gun which was photographed in some kind of Royal society museum in the UK in 2014. Hopefully I can get a reply from them and possibly precise measurements and more photos of the gun.It may be the museum holding it so lining someone to go in there may be necessary. I will see what status the situation is during the week anywa. Alf an old forumite/hunter/historian from south africa on accurate reloading was the guy who posted the first pics of this rifle back in about 2006 but he deleted most of his posts way back. I am not sure if he is even still around. I havent been so not sure who is still in the mix

By the way, great subject by Ripp, the modern versions certainly do exist. And I am guessing this is the Ripp aka Rip aka Daggaron off AR fame?