so after doing some tweaking to the gun and swapping triggers and parts, i have finally got my AR to the point i want it.


ive had my aimpoint for about a month now and I zero'd it in for 25 yards. After hitting a 5 shot group centermass at 25 yards, i used the ARMA DYNAMICS red dot zero targets. This is used to get a 50 yard zero at a 25 yard range.
http://www.arma-dynamics.com/red-dot-zero-targets.html

i managed to get a solid zero on that and was happy. I used winchester .223 hbpt 69 gr hollowpoints as those are the rounds i keep loaded in mags in case of a home defense, shtf scenario. i also used 55 gr norma .223 to verify the zero with other types of ammo

i go to the range again, and im using 55 grain norma .223 and 55 gr steel at 25 yards and im aiming about 1 inch above centermass, and my POI is hitting around 1 inch above centermass, almost like its a slightly off 25 yard zero. my point of aim should be around 1'' to 1.25'' above centermass at 25 yards with a 50 yard zero.

so the reason im asking this is that is it my aimpoint not holding zero? or is it just a poor zero and the ammo/my aim is partially the reason? I have yet to verify a real zero at 50 yards due to the locality of ranges near me at the moment, but i plan on it.

Always verify at the actual range you intend to have the firearm zeroed at. The target you used to get a 50y zero at 25y is good to get your gun close but should not be relied on for a dead nuts zero at the intended range. Also, different ammo types and weights will print at different heights and windage can be off as well, all out of the same barrel. If you zero with one specific ammo, lets say 69gr in your case, the zero will not be reliable for other weights/types such as m193-type 55gr.

So basically, only rely on your zero at the distance you actually zeroed the gun at and with the ammo it was zeroed with. Know your holdovers based on your actual zero distance and ammo type as well.

Are you saying that you zeroed your rifle with 69 grain HP ammunition and now you're wondering why 55 grain FMJ ammunition isn't shooting to the same point of impact?  If so . . .



Many people seem to think that the difference in the points of impact between two different loads fired from a rifle with the same windage and elevation settings on the sights are due solely to the difference in the exterior ballistics (trajectory) of the two loads. This notion is false.

The difference in the points of impact between two different loads (with the same sight settings on the rifle) out to say 75-100 yards will be due in large part to matters of interior ballistics; barrel harmonics and recoil vectors for instance. These components may not be the same from rifle to rifle and are not predictable using ballistic software. The only way to know what the difference in the points of impact will be, is to shoot the different loads in your weapon.

To illustrate the above points with a specific example, the graph below shows that there is nearly no discernable difference in the trajectories of the Sierra 55 grain BlitzKing and the Hornady 70 grain GMX out to 100 yards.





Yet, when I actually fired the Hornady 70 grain GMX load from an AR-15 that had been zeroed for POA=POI at 100 yards with the 55 grain BlitzKings, the group of the 70 grain GMX impacted 2.9” LOW and 3.7” TO THE LEFT of the point of aim.





...

I have found over the years that POI do shift and is very ammo dependent.  As noted by others above, very good info in the responses above.   I generally shoot X193 ammo, so all of my optics are sighted in for this ammo, except the rifles that only see 77 grain FGMM.

I have watched the Shawn Ryan video on 37 yard zero at 25 yards and tried that, and for the most part, does work and also tried other sight in at 25 yards to be on at other distances procedures, but for a red dot, and the majority of my optics are Aimpoints and EOTechs, I have found, try to find a location and if the sight in of 50 yards, which all of my dots are set up for, use this distance and confirm....if at all possible.  I can assure you, as hard as I try to use a "low at 25 yards", "a 37 yard zero" procedure, at 50 yards they are off.

I took my LMT out last week, I have not shot this particular rifle in about 2 years, it has an Aimpoint ML2 and was sighted in at 50 yards with X193 ammo.  It was spot on at 50 yards and after three rounds at 50, I hit the 12" gong at 200 yards on the first shot.  

Just my thoughts...

Bronc

thanks for the help guys. I managed to get to a 50 yard range and got a nice grouping.
im using 55 gr brass and 62 gr green tips.