twowheelhooligan, i`m very new to shotguns, I know how to shoot irons sights from a rifle or scope, even your old 870 shotty, but this 2 bead system has me confused, now i don`t shoot much, and was hoping on a 'simple answer', but this gun is a supernova and shoulders perfect to me, and i haven't messed with the shims at all, this being said, maybe you or someone else can better answer my question, I only shot 3 rounds threw my gun, once with a number 2 lead to see if it would fire, and twice at a moose with slugs about 50 yards, now I missed the moose completely, and i think i may have been shooting to low, but i`m unsure, thus im not sure if the mid bead should be stacked over or under, as i use it center which never worked, also keep in mind in a Canadian, so im unable to shoot in my back yard