Observations On The Effect Of Parallax Error When Shooting With An Aimpoint Comp M5 And A Trijicon

[Molon]

Observations On The Effect Of Parallax Error
When Shooting With An Aimpoint Comp M5 And A Trijicon MRO​

Some manufacturers of red-dot sights have made claims that their red-dot sights are “parallax free“. Most of us are already aware that this is simply not true at all distances. Inherent parallax error with a red-dot sight is typically greatest at CQB distances (MOA wise) and decreases as the distance to the target increases.

In this ballistic exercise we’ll be looking at the amount of parallax error occuring during objective, controlled, live-fire testing at the distances of 7 yards, 15 yards, 25 yards and 50 yards when shooting with an Aimpoint Comp M5 and a Trijicon MRO mounted on a precision AR-15. The Aimpoint Comp M5 has a 2 MOA red dot, as does the Trijicon MRO.

All shooting for this exercise was conducted from my bench-rest set-up using one of my precision AR-15s. This AR-15 has a 20” Lothar Walther barrel with a 223 Wylde chamber and 1:8” twist and it routinely produces 0.75 MOA 10-shot groups at 100 yards (with a high magnification scope). The ammunition used for this exercise was one of my match-grade hand-loads topped with the Sierra 52 grain MatchKing. Wind conditions on the range were monitored using a Wind Probe. The set-up was very similar to that pictured below.








The barrel . . .
















10-shot group at 100 yards . . .






The Wind Probe . . .







The Details


The methodology for this ballistic exercise was as follows . . .

Shooting from the bench-rest set-up with the Aimpoint Comp M5 atop the precision AR-15 at the initial distance of 7 yards, an 8-shot control group was fired with the red-dot centered in the sight window. Next, an 8-shot parallax test-group was fired in the following manner:

2 shots fired with the red-dot positioned in the extreme 12 o’clock position of the sight window.

2 shots fired with the red-dot positioned in the extreme 3 o’clock position of the sight window.

2 shots fired with the red-dot positioned in the extreme 6 o’clock position of the sight window.

2 shots fired with the red-dot positioned in the extreme 9 o’clock position of the sight window.


Additional 8-shot parallax test-groups were then fired sequentially at 15 yards, 25 yards and 50 yards in the manner described above. This simple methodology is illustrated in the two pics shown below. The solid black dot on the target was the point-of-aim.



The 8-shot control group at 7 yards.







The 8-shot parallax test-group at 7 yards.








Aimpoint Comp M5 Results

The 8-shot control group fired at 7 yards had an extreme spread of 0.039”, which at 7 yards is 0.53 MOA. The extreme spreads of the parallax test-groups are shown in the table below.









Trijicon MRO Results





I repeated the ballistic exercise described above using a 2nd-generation Trijicon MRO with a 2 MOA red dot. The results are shown in the table below.






I also conducted the 50 yard portion of the parallax test using another 2nd-generation Trijicon MRO with a 2 MOA red dot. The results were nearly identical to that of the first MRO. The extreme spread of the 8-shot parallax test-group was 7.46”, which at 50 yards is 14.3 MOA.



Comparisons

The tables and graphs below show the results from both the Aimpoint Comp M5 and the Trijicon MRO, side-by-side, for comparison.

Results in minutes of angle . . .










Results in inches . . .










…..

 

[LoonWulf]

Very cool. Ive known there was parallax error in red dots, but never seen it tested.

 

[MCMXI]

So for all practical purposes the Aimpoint is parallax free.

 

[herrwalther]

Another thing most red dots advertise is 1x or no magnification. Truth of the matter is the glass does add some magnification. If I were to call it 1.1X that would be generous as I believe it is quite less than that. But it is easier to put 1X rounded down, less confusing for most people. Same thing with parallax in red dots. It's just easier to put parallax free than 0.3" at 7 yards.

Still, I cut my teeth on the CompM2s and M4s. Did plenty of CQB gunfighter drills ranging from point blank to 20 yards. Thoracic hits were easy for pretty much anyone. T-box hits were harder. Parallax might play some role but I bet most of the misses were because it was shooting at a 1" x 4" rectangle on a target head as fast as possible. So I like seeing the math done. No experience with the MRO though.

 

[1KPerDay]

Very cool. Ive known there was parallax error in red dots, but never seen it tested.

Inrange tv on YouTube does practical parallax testing for their American made red dot series but they’re shooting at a steel torso at 25 or 50 yards. So there may be “some” shift but as MCMXI points out for practical use they are typically “parallax free”.

 

[DustyGmt]

Nicely done. Nice setup too.

 

[MCMXI]

Aimpoint is my go to red dot. I have a Comp M4s and a Micro T .... both great, but both kind of expensive.

 

[MCMXI]

So there may be “some” shift but as MCMXI points out for practical use they are typically “parallax free”.

Even the MRO is more than acceptable, even with gross misalignment. So once again, essentially parallax "free" for most applications and assuming nothing worse than gross misalignment.

 

[taliv]

you don't really need to shoot to test parallax though, eh? that just adds a variable. granted, it's a lot more entertaining

 

[rbernie]

I guess that holes in the paper are easier to show.