Just to let you know, the virgin front sight bases are installed on a virgin barrel, then the two holes are drilled/reamed and the pins inserted at a factory. if you are trying to put a take off FSB on a barrel that has already been drilled for the taper pins, it is most probably not going to line up correctly.
Is the barrel you are installing this already drilled? If so, an easy option is a clamp on style, that does not use the taper pins.