I recently installed a williams peep sight on my 397. Although it had at one time mounting screws. They where buggered up quit well. My hardest problem was getting the breach true and square on my small press.
any how. I read that the #64 peep sight tends to not adjust low enough. Rather than mess with the front dight I had to fill down the bottom of the peep bracket to get it to shoot POA to POI @ 25 yards.
This stuff is only fun if you love it!