Is 25 yards a good point blank zero for an AR22 with A1 ironsights?

works for me.

That's what I use

If you zero at 25 yards, bullet path passes through zero again at about 130.
The highest it goes above your aim point is 1.3 inches.
It doesn’t go more than an inch below your poa until almost 150.

In summary, you should be within about an inch out to 150.

I don’t believe that to be correct for 22lr.

It isn't.  With hi-vel ammo a 25 yard zero will have you about an inch over at 50 and an inch under around 80-90 and a couple low at 100

I'd keep it about 1" high at 25 yds to be close to 100 yds zero (for iron sights, that would be more than good enough in my book).  Depending on your ammo, of course.  Use this chart from MCARBO for reference if you'd like (I believe Rem 40 gr was used) -




https://www.mcarbo.com/store/pg/59-Trajectory-Chart-for-17-HMR-17-HM2-22-LR-22-WMR.aspx

A couple of issues with that.  For one, that chart is for a 1.5" sight height which is an inch lower than an AR.  If you sight in an inch high at 25 with an AR your midrange trajectory will be 2 - 3 inches above LOS and your zero will be beyond 100 by a bit.  I prefer a point blank zero of 1" with 22LR which is usually achieved with a 25 yard zero with the 2.5" sight height of an AR.

Name: .223 Cal, Federal HP, 36 grn
Ballistic Coeff: 0.125
Bullet Weight: 36
Velocity: 1179
Target Distance: 75
Scope Height: 2.600
Temperature: 70
Altitude: 1115

Ballistic Data
~~~~~~~~~~~~~~~
 Range  Elevation  Velocity   Energy     ETA         Drop      Max Y  10mph Wind Deflect
 0 yds     -2.60 in  1179 fps   111 fpe  0.000 sec    0.00 in  -2.60 in    0.00 in
25 yds     0.08 in  1112 fps    99 fpe  0.066 sec    0.81 in  -0.83 in    0.34 in
50 yds     1.01 in  1057 fps    89 fpe  0.135 sec    3.38 in  -0.16 in    1.33 in
75 yds    -0.00 in  1013 fps    82 fpe  0.207 sec    7.89 in   1.05 in    2.90 in
100 yds   -3.10 in   975 fps    76 fpe  0.283 sec   14.49 in   2.84 in    4.96 in
125 yds   -8.51 in   943 fps    71 fpe  0.361 sec   23.39 in   5.30 in    7.57 in
150 yds  -16.31 in   913 fps    67 fpe  0.442 sec   34.69 in   8.45 in   10.61 in
175 yds  -26.64 in   887 fps    63 fpe  0.525 sec   48.51 in  12.36 in   14.06 in
200 yds  -39.70 in   862 fps    59 fpe  0.611 sec   65.07 in  17.10 in   17.96 in

Yep you're right! I didn't even see that 1.5" sight height.  All of my AR optics are between 2.5-2.8 so definitely would mess up the drop!  Thanks for pointing it out.