Yesterday a friend came over and assisted me in mounting my Vortex HST to my 20" AR. We placed the rifle in a rifle vise/sled and leveled it using two bubble level vials set on gaps in the top rail of the receiver. Once it was level I looked through the scope at a 4' level we had clamped vertically on the fence post 30 yards away and lined up the vertical crosshair with the level on the fence then verified with another bubble level on the top turret of the scope. It was dead nuts on! I had never done it that way. Everything was torqued to specs, 20 inch/pounds. At first I thought it was overkill but now not so much.

What are your thoughts...? How have you mounted scopes on AR's?