Are you running a JM Pro or the 24" ported Turkey gun that comes with those sights?
JM Pro 22", the HiViz are add ons. I've run a set on my 1100 for the last 2 years without issue.
The reason I asked is because my turkey sights (Allen makes them I think) that came factory on the turkey 24" barrel always shot really high too. Even turned all the way down. I had to aim at the bottom ring or stand of a steel target.
The two JM Pro's I have fired have both been POA w/ shot but we haven't put slugs through them yet.