I put my Buckmaster 3x9x40 with Talley low mounts on my Vanguard without any problems.( no lapping) A good hardy hand tight to finish. Put front and rear rings at the same time and and when you feel the screws start to snug up stop. Do the same to all. I used the diagonal method and tightened each screw a little at a time, and what you want is to try to keep the same gap or space between the rings on both ends. Easy peasy. I did leave the laser bore sighting to a gunsmith. With your condition, I applaud you in living life to its fullest, and wish nothing but the best of luck to you and your girl in all you do.