I've got my irons zeroed at 50/200(225).

I got my Bushnell TRS zeroed at the same zero with an absolute co-witness a few months back.

Well, I just got a 1" riser because I wanted to try the 1/3 co-witness and I realized that I like it a lot better (much less clutter of the irons in my view).

Well, when I replaced the 1" riser over the 0.83, it did not change the postion of the red dot. It was still lined up with the top of the front sight post when I co-witnessed.  

Is this normal? I guess when I go to the range I'll find out for sure.

One more question. The range I go to has markers at the 3, 7, 15 and 25 yard line. I know with a 50 yard zero I should be around 1.5" low (at 25 yards).

Im kind of curious how low should I be at 3, 7, and 15 yards with my 50 yard zero?

Really wondering about this because my AR is my home defense weapon.

Also though about zeroing the red dot at 7 yards and leaving the irons at the 50/200 since 7 yards would be a lot more practical in close quarters of my home and I could just go with my irons for longer shots if needed...

Thanks.

Doesn't surprise me at all.  Ideally, with just that small change in picatinny riser height your zero would be off by a 0.17".  Sure, it's not always the case, but it should be :)

If your local ranges is only 25y, and your AR is a home defense gun, then I guess a 25y zero makes sense.   You'll be high to the neighborhood of 300y, and precise predictions are difficult to make unless you can test at longer ranges.

You should see the dot on the tip of your front sight when using irons regardless of whether you have absolute or 1/3 cowitness. The whole point of a red dot is that it is accurate no matter where in the optic you are looking. The dot can be in the center of the optic or on the extreme edge and will still be on target. Thus, when you look through the bottom 1/3 of the optic it will line up with your irons since they are both pointing at the same spot.