I bought a set of Ken Farrell standard height rings for my new Mark 4 to go on a 6.5x47L and while I paid attention to make sure I kept the tops of the rings with the correct bottoms, I failed to notice that there was a front and rear ring. Now I have the ring marked "F" on the rear and the ring marked "R" on the front. Is it a big deal? I didn't even notice it until I was putting the gun back in my truck after sighting in. Anyone else do stupid crap like this?