well I found out I need to change my sighting technique when shooting the iron sight... I normally just get a good cheek weld on the SOCOM stock, and look at the target when shooting the HS 510... the gun comes up on target and the dot is centered... well, no so for me with the Irons... found I am considerably more consistent if I track with a sight picture with fiber optic front centered in rear aperture to the target... 75 year old dog, new trick... regards