ok... curiosity got the best of me and i removed the "rib" to look at the regulation screw on the remington 45-70... the barrels are closer together in the middle than on the muzzle end... by about .250... in fact the barrels look hour-glass in shape... the rear sight is off-set about 1/8" to the right... there's a hash-mark that some-one put on the base... it's gonna be a week or so beforre i get to shoot...