Ring split, an optical illusion!
The caps are right, If you look closely you will see they are cut above center, this gives the illusion that the cap is smaller but if you set your scope in the bottom and stick the cap on top you will see they fit perfectly.
We do this because rings cut at the 3-9 o'clock on center, have a tendency to pinch the scope. If they are over tightened or if the rifle is dropped and the ring top hits something or something hits it, this can cause the rings to pinch the scope and leave permanent damage.