Secondary optic position

[Tex_OEF]

I have a question regarding the position of an MRDS as a secondary sighting option. My introduction to dots was with the RMR on top of the 3.5x ACOG when we were first issued M27 IAR's around ten years ago. I have standalone red dots on carbines and pistols now, but I recently mounted an RMR on top of the ACOG on my primary carbine.

Height over bore with the RMR on top of a TA31 is approximately 4.25in. Sighted in at 50yd, putting the dot at the clavicle area at 7yd places the round in the heart area. I haven't shot on paper with it at 100yd yet to measure the offset, but it holds on a 6in steel plate at that range without any hold adjustment. That's further than I would plan on actually shooting with the RMR, since the ACOG is right there.

I would think that the top mounted position would have an acceptable offset at close range, while being in a position that is usable when firing from either shoulder. There's no cheekweld of course, but my chin does contact the stock.

Most people I see these days seem to have their MRDS mounted at a 45 degree angle rather than on top of their primary optic. I have not had an opportunity to experiment with this myself. Can anyone clue me in on the advantages of this position (or another position) as opposed to the top mounted position?

 

[Slim]

*Not the most experienced by far with this topic between the 2 positions, I'll chime in tho after playing with it a little.

I would think both have merits/downsides. The sport shooters went to offset for cutting transition time as it only requires a slight roll of the gun between optics. And barrel offset can be adjusted or the same for ease of close range rds or medium/far range magnified.

Both have been used successfully in field and sporting. I'd really recommend playing with offset just to see which works best for you.

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[spectrain]

There are definitely some advantages to having an offset mount as opposed to mounting on top of another optic. Most importantly both optics are in the same plane or height above the bore. This means that your cheek weld can always essentially stay the same, with a simple flick or roll of the gun to move back and forth between sighting solutions. With the on-top method you are sliding your face up a down the gun, which without a ton of practice probably means you are spending some time hunting for the exact right spot each time moving from one to the other. With the offset you can also utilize the same zero for both optics, and end up with the exact same holds at every distance. Lastly if you are planning to rely on the MRDS as a backup sighting solution, if its mounted to the ACOG they are sharing a single point of failure. Although the ACOG is a tank and not likely to fail, if anything ever were to happen such as the mount loosening up or whatever, the MRDS would lose zero as well.

 

[Default.mp3]

1200 has the advantage of far easier use with NODs and the ability to be used easily on either side of a barricade.

 

[pointblank4445]

1200 has the advantage of far easier use with NODs and the ability to be used easily on either side of a barricade.

Yep...NV, Gas masks, and the ability to "Noner" (aim with the opposite eye)...sometimes comes in handy.
It's completely "ambi" unlike some other mounting options
Most importantly, in terms of getting into position for precise shots, it's one of the best positions for using it as a sighter for your magnified optic. If you're dialed up and/or have an optic with a narrow field of view (FOV) or have multiple targets, as you're getting into a prone or supported position, put the red dot on target and drop behind the gun without having to move, cant or otherwise disturb the gun and have your target in your FOV and not waste time hunting for it.

The biggest con is the height and the time/reps required to mount the gun without having to hunt for the dot and not lose time for CQB/speed use of the dot in that context



45 degrees off of the optic takes one off of the bore axis (as you're now mounted off of the optic's axis) and may make things a little more challenging getting a consistent zero and/or working holds precisely. It can be kinda ambi I guess

45 offset like the Badger Ord C1 or stand alone mounts can be some of the fastest and most consistent for transition between optics and for maintaining height over bore for consistent head placement. May not work ideally w/ NV or mask depending on height. May not work the best with lights or lasers like the MAWL that may obstruct the RDS. Also like with the COMM, mounting location might have issues with gas from bcg bleed off can gunk up the lenses (had this happen with the ocular of an ACRO in a COMM mount)

 

[Wake27]

Current experiment. I liked the offset but for reasons above and just due to its bulky nature, figured I’d try out the top mount.


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