Roger that, ill credit your forum name.

Looks like a lot of work has gone into this page, interesting.

What's most interesting is nobody acknowledged it before.

I hear what you're saying.  But one of the touted upsides to an RDS is the ability to shoot from weird positions, with less than an optimal cheek weld, and still be effective.  This seems like that could lesson the degree of how much that it is really true.  Although at real close ranges it's not going to make a difference on a torso.  But I guess that just depends on how bad the parallax shift is in actuality, and what distances you're shooting at.

I wonder too if the effect is as pronounced with a M4, M4s, Aimpoint Pro, etc, with the bigger optical window.

I personally prefer the larger RDS' because it's easier to find the dot from odd positions, etc, vs a micro RDS.

I have never really found the bigger window of the PRO/CompM series to be that much of a game changer when it comes to finding the dot.  Most of the weird positions (mainly stuff where you are laying on your back which isn't really ideal in the first place i guess anyways) i have run across where a RD seems to be an advantage over something like a VP or ACOG has had more to do with eye relief than with a left/right or up/down issue.

Not so. Traditionally sloped stocks allow the shooter to slide fore and aft to firmly plant the stock and cheek together and get a proper height, other wise a spacer has to be used. On a straight line stock it must be at the proper height or it is at an improper height... there is no adjustment. 1.50" is an improper height. You can see posts of mine from over 10 years ago where I would correct people calling red dots "parallax free" and I would call them "reduced parallax" sights. Proper technique requires proper optic height and an ability to get a solid cheek weld and consistently place the human eye at the center line of the optic time and time again. This is done with cheek to stock placement and consistent head position, which is not facilitated by hovering over the stock. That is simply not a debatable point, it is science and biomechanics. It is why the irons are not at 1.5" height. It is also why I don't have problems with a T1 when I shoot for precision or zeroing. It is also why I choose the SPR-S over the SPR  for magnified scopes. Hovering your head, whether in a red dot on top of a magnified optic, or a scope on a carry handle, or a 1.50" or 1.93" optic mount on an AR is always the inferior choice for getting reproducible accuracy results. Its also why people say that they don't find that red dot on top of the irons is a proper zero. Well they are using irons at the bottom of the window where red dot parallax is at its worst, of course its not working! Because you have improper optic height and don't have an absolute co-witness!

As for the NV head position argument, I wear NV on my weak eye and use an IR laser. If I need to use white light I can use my optic with my dominant eye. I cant afford nor do I have access to dual tubes.

I also noted the discussion of glasses looking up causing optical shift. I use and recommend Oakleys for that very reason. They do not shift.

I recommend basic fundamentals that work. Perhaps I am overly vocal and enthusiastic about expressing my viewpoint, but I am not wrong.

I fully believe the T1 has shift, and always have known so, perhaps it is more than I thought and the testing will be nice to see how much it is. I do not believe its enough to be concerned about for people running an absolute co-witness and practicing good fundamentals of marksmanship. As long as the shooters eye is perfectly centered to the T1 there is ZERO shift shot to shot or group to group, that is a fact.

So, I completely agree with you on many of your points. I'm going to be very interested discussing some of them further after I post the results.

As for the NV work- I advocate using the optic as your primary and the laser as a secondary aiming device or target indication device. There are advantages and disadvantages to both options. However, you can get a much more precise aiming point with your optic, especially at range. In a CQB environment, it can be difficult to ascertain which dot is yours on the target (there isn't always obscuration in the room to show the beam from origin to target) which can cause you to correct a POA on a dot that isn't yours and correct yourself off target. Getting in the habit of defaulting to using an active light source (which a laser is) is bad practice as well since your adversary may have NV devices as well. There is also the commonality in training point as well- try to have as much of what you do during the day be the same as what you do at night in a more complex environment. So, during the daytime, I mount the rifle, aim the rifle, manipulate the rifle the same as I do in an NV environment. The only difference is if I enter a lit room and need to go white light where I would lift my head slightly to look underneath my tubes (dual) to use unaided vision in my optic.

As far as your comments on the hovering or high height over bore- the results may show why some people have no issues with this and some do.

Finally the zero shift if you are perfectly centered. Yes, completely correct. Two points here though. First regarding the OP of this whole thing. When you take a shooter who may or may not have deeply focused on fundamentals and hard grouping before, their mental bandwidth has certain limits. For instance, if you lay them down and have them focus on breathing, natural point of aim, position, sight/ dot placement, sight/ dot alignment, trigger squeeze, follow through, observing where the sight lifted from, where the sight lifted to, where the sight returned to, etc- when you debrief a group and they have a shot that was away from the group they won't remember which shot it was or what they saw. So, they will have made an error and not be able to tie the error to what they saw at that place in time and then to the action they took or the corrective action needed. Two truths: 1- shooting error occurs at the shooter. 2- only the shooter sees through the optic. So, barring observing something at the shooter (failing to check NPA, observing the rifle move, firing at an inconsistent point of breathing, etc) the shot group debrief is more of a conversation between an instructor/coach and shooter. There could be several issues that cause a shot to , for instance, fall to the right of a group. So, you would need to ask the shooter questions to troubleshoot it: Which shot in the string was that? Did you check your NPA before firing? Were you confident that your sight/dot was aligned and placed precisely? How did your sights/ dot move during the firing process? Did your sights/ dot return to your desired POA naturally during the follow through? All necessary questions so that you can narrow down the list of possible causes. Herein lies the rub: when first attempting precise groupings, most shooters will have the mental capacity to focus on 2-3 things and still have any ability to recall what they saw. An example might be- just NPA, steady trigger squeeze, and only pulling the trigger when you are confident with your sight placement. Once they demonstrate the ability to recall what they saw and relate it- then you layer more things to focus on (prioritized by what you see in the group as possibly having more effect) as they continue to demonstrate the ability to recall more. The goal of this is to push them to become self diagnostic- seeing error at the moment it happened, either through he sights or how it felt, and them being able to immediately correlate it to what they did and correct it before the next shot. So, with what I have just described above- this is what I have observed with the T-1: shooters have to focus much more on keeping the dot perfectly center which reduces their ability to closely focus on the other tasks and checks. This slows down the pace at which we can layer additional tasks to focus on. It also frustrates the shooters because they aren't getting any zero adjustments like the rest of the class (I generally do not give students zero corrections until they have placed a consecutive group in the same location without major error). While you explain to them, that it doesn't matter where they group on paper, as long as it is consistent and without major error and to not rush a zero correction- the natural desire of a shooter is to see their rounds in the center of the bullseye. So, with what I have just laid out- this is the basis for my T-1 stance in the specific course where we focus on fundamentals through precision grouping. For 3 years, every T-1 shooter I have had struggles with POI shift, it slows their progression relative to the rest of the class, and in many cases- it slows the progression back to further distance of the class as a whole. I think that 4 or 5 students in this course have posted in this thread about this as well.

I have heard the argument- you should teach them how to use the optic they have. My primary mission is to teach fundamentals, work arounds for equipment issues is secondary. If a student shows up with bipods on his rifle and his focus becomes ensuring that the legs are distributed during NPA changes, loading/unloading the legs, etc and other tasks fall out of focus- the bipods are coming off and he's going on a bag. Keep it simple, gear isn't a substitute for fundamentals, but gear can get in the way of fundamentals.

Now- one final point about the consistent cheek weld. I agree with you that it is important (with some red dot optics, definitely not all). However, the acceptability of the optic's sensitivity to imprecise head alignment is subjective to your intended use. If you just lie in the prone, sit on a bench rest, or stand in front of a target at 5yds in jeans and a T-shirt- then you can probably get a high degree of consistency there. However if your intended use involves CQB, protective masks, shooting in/around/ under vehicles, body armor/ helmets, etc- then your ability to get a consistent cheek weld starts to fall apart. So, making sure you are aware of the characteristics of any optics you are considering and how they will perform in all situations might be useful information.

You and I share the same observed opinion on eyewear.

After reading this I grabbed a rifle with a Meprolight tru dot rds out of truck to test it. I only had about 60' to work with do to being in my work parking lot, I braced the rifle and centered the dot on a 2"x3" reflector on the side of our box truck. This is what I observed:

Extreme 12 o-clock: No shift

Extreme 6 o-clock: 3/4"-1" shift low

Extreme 3 o-clock: 1" shift right

Extreme 9 o-clock: 1" shift left

The meprolights window is very large, this seems pretty good as far as performance, would you say the same?

If you have the time before Monday (when I'm closing out remote testing submissions) , run the test I've listed. Get a buddy or family member to run it as well.  All the forms and instructions are in the shared Dropbox link. I'll be happy to include your data in the comparative results.

Not everybody's face is shaped the same.  Cheekbone structure varies.  To me, it sounds like you're contradicting yourself.  A traditional stock allows for someone to find the right spot by going forward or backward due to the slope, but an AR 1.4" height is perfect?  I'm not following.  

Plus, how do you account for people that can shoot well with a height higher than what you're saying?  I have shot more than a few times with scopes on top of the handle, or even my M1A on the Springfield mount that is high and get really good results?  Or at least fair results?  

I agree that there is probably a sweet spot for optimum cheek weld and going too high is going to affect that.  But where that exactly is for everyone may be a bit different and it may be a bit higher than standard AR height for some.

I'm not sure if you are only talking about RDS or not.  If that's the case, I have way less experience.  I have not shot with them very much.  Most of my shooting has been irons, or scopes.  

This is typical of what I've found over the years with less than optimal optic height on an AR.  Or my M1A.  My M1A I can consistently shoot around 1.5 MOA with the scope on it and it's hiiiiigh.  

 

Never had an issue with the T-1's I own personally or the one sitting on my work M4.  All have been through numerous training sessions and carbine classes over the past several years.

If anyone wants to sell me their shitty, parallax ridden T-1, I will give you $100 for it.  Just IM me.

If you have a T-1 that does not exhibit aiming dot movement, would you mind testing it with some buddies before Monday? I would really like to include your data if that is the case.

Did some more testing. Using the same extremes for sight pictures, I was able to get 20 out of 20 hits at 100 yards on a 12in steel gong.

T1, 2moa dot, M855. 

From your previous page pics it looks like a 9" would have been a problem, potentially, and 12" may have seen some outer ring hits