The closer you zero your weapon the more exaggerated the movement becomes. When you zero at such a close range you are also having to overcome the holdover, which makes the numbers that much more severe.
^ This.
@SMSgtRod - mechanical offset's effects are greatest at distances below 10 yards. As you bring the template closer and closer, that difference becomes more and more drastic.
This is why close-distance zeros are universally not recommended by any SMEs in the CQB arena.
At the minimum, I would zero at the 25 yard line.
From there, it's time to learn the offset of your optic/mount combo at CQB distances, from contact to 25 yards.
The following is written by the late Pat Rogers, and it is probably the most intuitive and yet comprehensive write-up on the subject of mechanical offset I've seen -
For our purposes, mechanical offset relates to the difference between the line of bore and the line of sight. This distance will vary from one gun to another. Additionally, the sight and mounting system will also influence the difference. All handheld firearms have a certain amount of mechanical...
www.swatmag.com
^ It's written for the .223/5.56, but the ideas are still the same.
That bullet never "rises" as it comes out of the barrel: that's a physical impossibility - rather, it's the fact that you've essentially tilted the barrel up and you are intersecting bore axis with that of the sight plane, that causes the "rise" in the bullet between the muzzle and the near zero -
^ Taken from -
https://cowboytacticalgear.wordpress.com/2014/02/10/so-you-want-to-zero-your-ar15/
To be effective at any distance, you'll really need to zero the weapon system properly. Part of this capability will mean that at CQB distances, you'll absolutely need to instantly and instinctively compensate for mechanical offset.
Remember in one of my first posts on this Forum that I admitted a shortcoming in my marksmanship, when under stress?
https://www.thearmorylife.com/forum/threads/lets-see-your-ar-setups.258/page-2#post-3579
This was exactly what I was talking about.
Under the stress of being in the live-fire shoothouse environment for the first time ever in my life, once the scenarios got more involved and the problem-solving more taxing on my processor ("brain"), I began to drop shots outside of that "eyebox" head-shot kill-zone, and thus failed the demanding marksmanship standard set by Joe Weyer.
Did I completely miss the head? Not once - I was actually always well within that "inverted triangle" critical-CNS zone - but I was each time just outside of the eyebox: the pressure of the situation made me "brain fade," as Pat Rogers so eloquently put it in that article above.
I decided then and there that I'd pick up a few "basic" carbine courses that summer to remediate, and followed-through until I was able to instinctively compensate for offset.
