I'm shooting the tru glo adjustable iron sights but I seem to be getting variations in my POI from shot to shot with the same shell especially with different shells shooting HTL. I am thinking the variation with the same shell could be operator error but I don't notice this with lead. Lead shells it seems to stay the same from shot to shot and shell to shell. I notice with the majority of the patterns you see posted the POI is way off..anyone figured out why??