In the mid 1800's, double English guns, according to Forsyth, should have sight leaves that all fold flat. Sighting for point blank shooting
is done by simply sighting down the rib and using only the bead at the front. Sufficient elevation is given by the larger breeches of the barrels.
My own .69 rifle has 3 leaves that all fold flat. Point blank shooting, out to 50 yards, is taken over the rear sight boss, putting the bead on top
of the folded front leaf. This gives exactly the same elevation as if raising the rear leaf.
With the normal trail walk charge of 82 to 85gr. 2F, this gives a 25 and 50 yard zero. With the hunting load, this sighting, flat over the folded leaves
gives a 100 yard zero. Thus, for normal hunting range to about 120yards, no leaf needs to be raised if there isn't time. The accuracy with this
arrangement is just fine.
