Do both scopes have reticles with slash marks? If so, usually MOA or MILRANDIAN.Set up a ruler at 25 or 50 yards, measure with a tape to be exact from the front of your scope not the gun.Now set both scopes to 10X. At 25 yards a MIL scope should read 2.5cm or 1 inch.A MOA scope will read about 1/4 inch. So 5 marks = 1.25 inches.You need a ruler and 10X! -Y