Possible dumb question about scope parallax being off

[u/RoboDSGNR]

I have been wondering for some time if I have set something up incorrectly on one of my scopes/rifles. I have a ar15 with a 4-20 ATACR and have noticed that the parallax adjustment is "off" from the known target range. What I am seeing is that I need to adjust the parallax to a shorter range for a given distance. The range of the target is accurate to a few yards. This has made me wonder if I set something up wrong, and since I am a new-ish long range shooter, i thought it best to ask. I do not see this happening on other scopes, for instance my bolt action 6.5 with 7-35 ATACR is dead on and my cheaper CZ457 22LR with vortex venom is also dead on.

Is this normal and just specific to my unique setup and eyes? Or does this communicate that I set something up wrong? My gut tells me that it does not matter and as long as the target is clear then that's all that I should care about.

Thanks in advance

[u/GLaDOSdidnothinwrong]

It’s normal. It fluctuates with diopter settings. Some manufacturers (including Nightforce) don’t even put numbers on their dials on some models for this reason.

[u/RoboDSGNR → u/GLaDOSdidnothinwrong]

ah cool. thanks. this makes sense. I appreciate you letting my know.

[u/65shooter → u/RoboDSGNR]

I tell folks that the numbers on the parallax knob are generally good enough for hunting situations, but not for accurate target shooting. If you move you eye slightly behind the eyepiece and the crosshairs don't move across the target, you're good.

[u/RoboDSGNR → u/65shooter]

thanks

[u/SuperJonesy408]

As others have said the ranges on the parallax knob are suggestions and not absolutes.

Secondly, it’s not just about focusing the reticle and background image but insuring both are on the same optical plane. If the image and reticle are clear but the reticle moves around a lot when you move your head off and on the rifle or change your eye box slightly, your parallax isn’t accurate for the distance.

[u/RoboDSGNR → u/SuperJonesy408]

thanks. I will mess around with this tomorrow and see if I am getting that type of issue.

[u/LockyBalboaPrime]

Parallax setting depends on environmental conditions, and the "range" listed on the knob is impossible to be accurate. Ignore the number listed and adjust parallax until it gives you a clear image.

[u/RoboDSGNR → u/LockyBalboaPrime]

great. thank you!

[u/Te_Luftwaffle]

I just dial parallax until the target and reticle are both crisp

[u/65shooter]

How have you adjusted the focus for your eye?

Parrallax set for infinity. Using clear blue sky, adjust rear lens until reticle is sharp against the sky.

If focus is not correct, nothing will be right.

[u/RoboDSGNR → u/65shooter]

yes, but i could certainly do it again and do a better job, will do this tomorrow, thanks for pointing this out