You can do the same thing with iron sights if you have a 'barrel-clamp' mount or some other way to affix the laser without obstructing your view. Shoot your group. Mount the laser (it can be mounted in advance, but if on the barrel, you may worry it affected impact), then put the dot where your bullet holes went, keeping your irons on the original aiming point (again, using a rest to hold the gun). Binoculars or a spotting scope can help if you are sighting in at a long range. Once your laser dot is on the bullet holes (group) then just adjust the irons to be aimed at the laser dot. If you're sighting in at very long range or in bright light, take a spare chunk of bicycle reflector (red is perfect) with you and put it where the group center is, then go back to the bench and move the gun so your laser lights that up, then adjust your irons to that point.
Works fast and is quite accurate, and one way to quickly sight in with essentially only one group. You can fire the group offhand or whatever you prefer - the gun rest is just for when you're adjusting the sights to hold the gun still.
And no - you don't have to "use laser sights" to do this - take the laser and mount off and put it away until the next time you want to sight in with your scope or irons.
As an aside, here's a nice set of videos on laser sight adjustments. http://www.crimsontrace.com/support/sighting-guide/?
The one on 'parallax' needs to be read by many people I know who get frustrated with zeroing their laser sights, especially ones offset to the side.
