IMPORTANT NOTE
The pic above shows the flat mounted finger tight... Before the bolts are tightened with a socket the flat must be centered in the jig. This is the single most critical step and I used a set of reloading calibers to measure between the holes on each side of this rail to ensure that the flat was centered...
NOTE: The flat was lightly greased using axle grease on all sides before bending. This is important as it will help prevent streeching of the receiver or deforming the holes in the receiver.
NOTE: I used a Ball Peen hammer to fold the tops of the rail over. A good heavy hammer with a solid but even blow working from one end to the other produced a nice flat surface...