Put the calipers to my .30-06 Express setup today (medium Ruger ring set, Leupold 2.5-8x scope) and there is 0.090-inches between the top of the rib and the bottom of the objective housing.

For comparison, I removed the 3.5-10x40mm Leupold scope from my 338 Express so I can put it up for sale and there was barely daylight visible between the rib and objective. The two definitely didn't touch, but you'd need a feeler gauge to measure the gap.