I just got a 2007 1895 with a 26inch octagon barrel and it does the same. If I have my scope set for zero with my 500 grain my 300 grain will shoot lower. But I have a Nikon inline XR mounted on my rifle where I can zero out the adjustment turrets without moving the crosshairs. So since I shot between the 300gr, 405 and 500 grain I made a little cheat card that I laminated with how many clicks I have to adjust for each bullet if I have it zero on one or the other. Lets say I am at the range and I been shooting 300 grain downrange and I decided to shoot maybe 405 or 500 grain I look at the cheat card and turn what ever clicks it needs on HORZ and VERT and zero out the turrets and I shoot I always hit around 1-2 1/2 inches of my point of aim. I have all the info I need on 4 cards for 25yds, 50yds, 75yds and 100yds. Having all that info on cards that been laminated makes it a little less hectic. Hopefully I got the grammar and stuff right I had a stroke a couple of months ago and still recovering.