Such a delicate contraption imho has no place on a real, hunting dr! Apparently the two sight leaves are changed by inertia by firing the first shot. In case of a misfire the wrong leaf will still be up for the left barrel. A little bit of dust or hardened oil will certainly stop it's proper function, so one day you will be shooting at an enraged animal with the wrong barrel and/or sight leaf, or, worse, with both leaves out of function because chnging stopped halfway. Just another bright idea the world doesn't need!