Bang on your scope to set adjustments!!
Ya.. you read that correctly.. its no typo.
After spending $50 or more trying to figure out why I could not get my Nikon Slughunter scope to hold zero, and why a calculated adjustment didn't move the point of impact the correct distance, I gave up and called a master gunsmith for advice.
I have replaced rounds, had them tested, replaced the scope, remounted the scope, etc etc. Nothing worked.
Then, a master gunsmith told me to take a piece of wood block and tap the scope each time an adjustment is made. He explained that the mechanism inside is spring driven and sometimes it needs a shock to seat it into place. He went on to say that this usually is done with the recoil of the gun automatically but sometimes it requires a tap from a different direction.
Seems my problem is now solved. Each time an adjustment is made, I give the scope two wacks on the front, back, top adjuster and side adjuster. Seems to work like a charm.
Hope this helps save someone money on wasted ammo.