The distance between the red dot and magnifier doesn't really matter as long as the red dot magnifier sight picture is clean and the reticle is centered.
A significant gap between red dot and magnifier placement doesn't matter as long as the top rail setup doesn't look too sloppy.
Let's take a look at some configurations below:
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Red Dot Magnifier Sight Picture
Dot Size Doesn't Change
Features Holosun 3X Magnifier
Red dot magnifier sight picture basically look like a magnified prism scope. The magnifier doesn't feature a reticle, but the shooter with can see see the dot with much better clarity.
It helps with shooters with astigmatism, and finer zero.
The red dot reticle remains the same size when looking through a magnifier scope. 1 MOA will still be 1 MOA. 2 MOA will still be 2 MOA.
If the reticle looks blurry through the magnifier you should try the followings:
- Correct eye sight or wear glasses for shooters' with astigmatism
- Adjust the diopter to focus the reticle
- Clean red dot or holographic sight's lens
- If reticle still looks blurry, then it means the red dot sight inherently have emitter refraction error, try another one (Check out our best red dot sights guide here on our site)
Dot Brightness Setting Affects Sight Picture
If the dot brightness is too high, the emitter glare will fill up the FOV, and it can obscure targets downrange.
Just dial them down when appropriate to see a clean sight picture.
Can't see IPSC steel target (68 MOA EOTECH Reticle)
It's easier to see now after dialing down the brightness
The same applies to a single 1 MOA dot
Red Dot Magnifier Setup - Distance Between Them
Mount Too Close
Features Vortex Micro 3X Magnifier
Mounting the two optics too close isn't a problem if there is enough clearance to flip the magnifier to the side without scrapping the red dot.
Just make sure it can be fold/unfold without bumping into each other.
Quick detach magnifier mount makes the adjustment so much easier. Highly recommended over a fixed mount.
Shop for a red dot magnifier here
Mount Too Far
Mounting the magnifier too far behind the red dot isn't a big problem either if the sight picture is clear.
If the red dot magnifier sight picture looks blurry, the user just need to adjust the diopter to focus the reticle. Then center the reticle.
Above is the Vortex Micro 3X and Trijicon RMR combo.
The RMR's American Defense QD lever forces the Micro 3X to be mounted 2 rail slots back. So different types of mounts can affect how close they can be mounted together
A 1X red dot doesn't have eye relief limitation, however, the magnifier scope does. Please be mindful to have enough eye relief distance based on how you cheek weld the rifle.
It's okay to move the red dot forward if need to as long as the optic to eye distance works for you.
There are forward leaning red dot optic mount available on the market, and the user can shift any ring clamped magnifier (Aimpoint 3X or 6X) a little bit forward.
For example above, the QD lever gets in the way of gripping the charging handle latch if the magnifier QD level mount is too close to the rear.
Try mount them more forward so the shooter's finger doesn't bump into it, or use a larger latch charging handle
Optic height can be a problem if they misalign without any rise spacer to compensate.
It's okay to have a slight height difference as long as the reticle can be centered