Problem adjusting elevation on Tech Sights (Marlin 925)

[ggunner]

I'm having an issue w/ setting the elevation on a newly installed set of Tech Sights on my Marlin 925R. Perhaps it's just error in how I'm using them, but I've cranked the elevation down to the lowest it will go and it's still shooting too high (between 3-5 inches above target at 25 yards). Anyone experience a similar problem or have any ideas as to what the cause might be? Thanks!