For a new barrel or moving a scope from one firearm to another, I use a
Wheeler Laser Bore Sighter. I set up in my garage and place the target 25 yards away. Setting up in the garage prevents people driving by seeing me aiming at the target. With the rifle/handgun in the gradle, the bore sighter is attached to the muzzle.
The bore sighter that is now attached to the muzzle is then turned on. The green laser is aimed at a small orange peel off sticker on a white backer 25 yards away. The cross hairs are then brought to center on the green dot.
When I head to the range, my first shot is normally around 50 yards and the cross hairs are adjusted as needed. The next rounds are fired to a 100 yards and a zero is established.
If this is a new barrel, I will begin load development at the range. If it is an establish barrel and I just switched out scopes, I'll shoot several more rounds just for practice as a regular range session.