I have a RB in 454 with a 8 3/8 barrel. I installed a square -B pinnical rail mount that mounts to the vent rib, I mounted it all the way back towards the hammer. I have a millet red dot scope that uses weaver rings to afix to the rail. My problom is that ther is about 4 inches of movement up and down the barrel with several mounting poibilities. So do I mount it all the way back or put it in the middle. Moving it to the frount and down the barrel would be harsh for recoil.