I believe you'll find out it's actually the stock weld. If a person doesn't mount the rifle the same way it will cause a slight change in impact due to the positioning of the eye and how the sights are viewed. Case in point shoot an AR platform rifle with standard peep sights. The shooter needs an anchor point to accurate shoot. I always taught touching your nose on the charging handle. That way there is a constant anchor point that places your eye in the same location so the same perspective of the sights are viewed. Just my .02 cents. Still good shooting cayugad.