Check your Gamo scope
If your Gamo scope does not hold zero check the two star screws on your adjustment dial and tighten a bit.
shooting with my grandkids the scope would drift right.
I re zeroed a few times but it continued.
What I gound the two phillip or star screws which holds the adjustment dial in place and makes the MOA clicks relevant had come out.
To my chagrin I took the windage cap off only to find the adjustment dial in my hand.
and the two tiny screws fell to the ground.
I found one.
and checked Elevation which also was loose.
ive contacted Gamo customer service for help.
so we will see.