some people find them helpful. I never had one do much more than get on paper 100 yards. I like to place the rifle in a vice or bags and if possible remove the bolt and sight through it and line up the scope left to right then up and down , a plumb straight edge is good like a door frame , then shoot at 25 yards adjust to hit center l-r and 2.5 inches high . shoot at what ever range you like and be set. I have seen severl gun smiths do it this way and they have the collimators and don't use them.