I am new to shooting rifle, I just purchased my first AR-15.

I purchased an Eotech EXPS2-0 holographic sight. I sighted this sight in at 50 yards, shoots perfectly.

After this zero, I purchased an Eotech G33 magnifier. I moved my holographic sight to install this magnifier.

I went to the range to confirm/regain my zero on my holographic sight as I moved it to install the magnifier. My groupings with the holographic sight at 50 yards were perfectly fine/dead center.

Afterwards, I flipped the magnifier on for use, shot a perfect group at 50 yards.

With the magnifier, I shot a group at 75 yards and 100 yards. Both groupings were high but centered (so they were just high). I turned the UP/DOWN knob on the magnifier thinking that would zero the magnifier like an idiot. I was not aware that the UP/DOWN and LEFT/RIGHT windage knobs on the magnifier were only to center the holographic red dot in the lense of the magnifier. I thought the knobs on the magnifier were to obtain a zero when using the magnifier.

I left the range shortly after assuming that my groups with the magnifier will just be high and to be okay with that and aware. Is this called a holdover?

How do I go about obtaining a zero for my holographic sight AND my magnifier so I can shoot dead center no matter if its between 25-100 yards.

The range I have access to has 3 lanes - 50, 75, and 100 yards.

You won't be dead center at all ranges with any zero due to ballistics.

FPNI as usual

From 5 yards out to 100 will all be different zeros. So learn your holdovers and holdunders. Then as the bullet starts dropping they will intersect with some of your zeros.

Popular zeros include, but are not limited to, 25 yards (which is basically the same as 300), 50 (which generally lines up with 200), and 100.

Disregard.  I misread his post.

Just WOW.  Think OP should take a hunter training course.  This is Ballistics 101 material.

Research “Battle Zero”

OP, head over to YouTube and start watching some videos from NSSF or others on zero distances and bullet trajectory.

You have much to learn but it will be fun in the process.

I recommend you attend a Project Appleseed. They're in pretty much every State, and you'll learn about this, and all kinds of things you haven't even thought of yet. It will give you a solid foundation of the fundamentals before bad habits can develop.

It's a tough crowd to be astonished he's asking for guidance when: he's new to shooting rifle, just bought his first AR, just joined less than a week before posting, and it's his 1st post!

I knew all about bullet trajectory before I was 12 years old.  Even if a first rifle, handguns work the same way.  But, yea

I guess the force of gravity is no longer taught in school either?

Not everyone was lucky enough to grow up with parents who taught all this stuff. We need to be supportive of the new folks. At some point in our life, we were all new as well.

Just the thought that people might think that a bullet leaves the barrel and flies in a straight line like a laser beam until it evaporates or something scares the hell out of me, and it should you.  Maybe they might just need a little "slap" in the face and a wake-up call!?!

Might I suggest you head on over to GD, where you will fit right in and can virtually slap whoever you want.

Oh Lord, "slap" was not literal.  The dumbing down of the public is getting alarming of late.  Just WOW!

You do have an opportunity to un dumb some of the public if you choose to. Or you can just complain how the public is getting alarmingly dumb.

It’s obvious he was speaking about common sense and thinking things thru logically. Unfortunately common sense isn’t so common today and people thinking problems thru for themselves vs going to the internet just isn’t a thing anymore.

I can see where someone new could think there wouldn't be a meaningful shift over 50 yards. If we were talking longer distances, then I'd agree. But as you know, gravity isn't the only factor in play here.

You can't, at least within the gravitational field of any substantial celestial object.

You should zero for whatever range you want (we like the 50 yard zero), and then learn your holdovers for other ranges.