Zeroing your airsoft gun red dot sight
 

I FINALLY have a red dot on its way in. An Aimpoint m2 clone. Paid $60 for it. When it gets here I wanna know the proper format for sighting in my site. Make sure to turn hopup off? On? Somewhat? Range I should be shooting? then after its zero'd I only ever have to mess with my hopup to add decrease range?

set the range of your gun with the bb weight you are using with the hopup.

zero your sight to your preferred range.

Actually think I'm gunna throw .25 in and set it to a good range with iron sights. Then throw the red dot on and zero it in

I use a bore sight and sight out my long guns to about 125 feet
and short guns (MP7) to 75 feet

I set my hop-up first, then add a bipod (just for bench setup), alight RDS at given range (usually 100' for me), finally set BUIS with the dot (a LOT easier if your sight co-witness) and remove bipod.

It's useless to set your sight without your hop-up, you will have some when you play, and it pushes the trajectory a bit up...

Hmmm ok so I need to set hop up first? And need to fix my rds for different ranges?

Just set your gun to shoot the straightest you want it to. Next, try to use some steady bipod or anything else, and adjust your red dot to point where your gun is shooting.

Depending on how high your RDS sits compared with your iron sights (flip-up are the best for this) you can co-witness your red dot with your iron sights. This means, if you have flip up sights (even just a rear flip-up and stationary front will help with this), flip them up with your RDS mounted and adjust your dot to "mesh" perfectly with your iron sights (i.e. the dot sits in the middle of the sight picture for the rear sight and sits at the top of the front sight post). Then you will be able to flip them down (or just the rear down depending on the style you already have) and you should be almost on dead center. Of course, this is dependent on whether or not your iron sights are garbage or not. So long as you have everything nice and centered you can simply adjust the hop-up according to range (as that is obviously what it is used for). You may need to make small adjustments, but the key there is small.

Edit: Depending on your game play you will want to use different weights of BBs. .28g BBs are great for outdoor play and situations with more medium-long range engagements as from my experience they tend to have less horizontal drift and thus give you tighter groupings. If you are playing indoors or are constantly transitioning between indoors and outdoors, .25g BBs are probably your best bet, but at the longer ranges they tend to be more affected by air resistance and wind. Again, this is just from my experience, and because I play mostly outdoors, .28s are usually my go to for my AEGs.With pistols I generally strictly stick to .25s, but this is my personal preference.