Ditch,
If you bench rest it to get a zero it will produce different groups than when you fire it naturally - it is all to do with harmonics.
You need to take well aimed shots to group and zero, not any one else as everyone's aim and eye is different, and they need to be taken in a stable natural hold not bench rested or you will have to do it yet again (unless you want to take the workmate out shooting with you?)
OTC