POI 6" low @ 25yds, Magpul MBUS, PSA 14.7" upper,

[subwofer2]

Here are the facts/details:

At 25 yards the point of impact (POI) is 6" lower than the point of aim (POA). Group size was the size of a quarter, 10rds 62gr Wolf FMJ unsupported. Similar performance with 55gr JHP and American Eagle M193.

My sight radius is 17" with a Magpul MBUS Gen 2.

I have a F marked front sight base. Front Sight Post (FSP) was installed to factory zero (flush).

Palmetto State Armory 14.7" (14 7/8") 1/7 twist Hammer Forged Mid-length Upper. Smith Vortex G6A2 has a hidden pin and weld.

My FSP measures .270" from round to the top of the post, .787 overall.

Considering the following to be true:

To change POI 1" at 100 yards the sight correction is .0044" per in. for a 16" sight radius.
To change POI 1" at 100 yards the sight correction is .0050" per in. for a 20" sight radius.

My interpolation:

To change POI 1" at 100 yards the sight correction is .00455" per in. for a 17" sight radius.

What can I do to correct the issue? Shave the FSP down?

Given my current POI is 6" low at 25yds or 24" at 100yds I need to remove .1092" (24 x .00455").

This will result in my FSP being .1608" tall.


Can anyone tell me if I'm on the right track? Is there anything I'm over looking? Should I be trying something else? Why is the POI so low?


Before and after (concept if you will) of the modified FSP.

My Rifle:

 

[Awesymoto]

Re: POI 6" low @ 25yds, Magpul MBUS, PSA 14.7" upper,

so your FSP is maxed out in elevation ?

 

[subwofer2]

Re: POI 6" low @ 25yds, Magpul MBUS, PSA 14.7" upper,

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Awesymoto</div><div class="ubbcode-body">so your FSP is maxed out in elevation ? </div></div>

I can turn it lower (clockwise) but not far enough to make enough difference in the POI. Even bottomed out the POI will still be low.