Getting the sights and red dot zero.. here's how I do it.
You must be further than 15 feet to adjust the sights and red dot becaus eof the hop up system.
And always use constant weight of bbs for perfect results.
It's better to zero the red-dot and then have your sights, or other way around, I prefer red dot because it's easier for me.
I go prone, I get cardboard and have 4 squares, like a cross in the middle. Like a target, I shoot 3 shots to see where my shots go from my red dot at where it is set.
Then, you see where you hit, and adjust right or left, and up or down. Reset your target by taping the shots in the cardboard/target, or get a new one.
Then, shoot again and see where it shoots, and keep adjusting.