Years ago, I good friend of mine and a collector of fine doubles, had a 6 bore side by side ball and shot gun. It had 36"(or 38") tubes and a rear sight as well as a front bead or blade - can't remember - about 14 pounds. He sent it back to H&H for refurbishing in the 70's and they reamed the tubes to about 5 1/2 - gun looked brand new when he got it back.

Wil used it for trap shooting for a lark at the local summer turkey shoot, shooting 2ounce of 7 1/2's and 120gr. 2F or so- might have been 130gr., I think.
The gun was so heavy, you could not stop the swing ounce initiated and bust birds it did. Lots of smoke, and very little recoil.
The breeches were massive. H&H noted it was in excellent condition for an 'African Gun'.