I have never used rifle sights when I was hunting with standard slugs, always beads.
I would not want to use buck for hunting, even though for some reason in Iowa it is illegal to use Buckshot. With 9 pellets seem that your killing power would be split 9 different ways rather than just one big fat way. Hopefully hitting a vital part at range.
Slugs are the way to Go.
You can always get some aftermarket sights that go on your vent rib.