Help me think through this - RDS vs ACOG

[RogueElephant]

@Vinh

The specific weakness of the 1.5x ACOG is indoors in low light, with or without a flashlight.

Without a flashlight, there isn’t quite enough visual reference to aim through the scope, so you end up defaulting to using it as an OEG, especially when you and/or the target is moving. Depending on your eyes, the point of impact disparity may be significant. For example, for me, the POI is off by 4 inches at 7 yards, which is unacceptable.

With a flashlight, the reticle gets washed out. If the target has light colored clothing, then it’s merely akin to using iron sights. Dark colored clothing, the reticle blends in a bit much.

Thank you!

The thread has focused on solutions, which really is the bottom line, but you have answered my original question. Now, back to solutions.

Understanding that it too will be a compromise, it sounds like the TA44SG-10 is my best bet. rob_s answered my question about mounts but I didn’t completely understand the answer. Apparently, the choice is to mount the ACOG on the carry handle, using the mount that comes with it, or buy LaRue or ADM mount and mount it directly on the top of the receiver. Is this right? Wouldn’t be preferable to mount it closer to the bore axis?

[rob_s]

The idea that things should be closer to the bore is applicable in bolt-actions and similar where iron sights are similarly close to the bore and where the cheekweld occurs below the boreline due to the stock falling away from the centerline… On the AR system where the iron sights are ~2.5" above the centerline of the bore and the stock is inline with the bore putting your cheek above the barrel you typically want to mimic the elevation of the stock iron sights to some degree. If you go with the “special ring mount” version of the Compact ACOG you will definitely get the optic centerline closer to the bore, but doing so may get it so low that you can’t actually get your head low enough to see through the optic.

The Trijicon factory, Larue, and ADM mounts will put the centerline of the Compact ACOG at the same centerline as the stock iron sights +/-. If, however, you mount the optic to the carryhandle as originally designed you will wind up with the optic 3"+ over the boreline. What the various mounts do is replicate the profile of the carryhandle channel but at a height such that mount+optic=optic centerline at ~2.5" above bore.

[rob_s]

Here’s somewhat of an interesting pic from the old days. The goal here was to have two rifles that were set up as close to identical as possible for for two different roles. At the time I was wearing contacts that were not corrected for my astigmatism and the RDS bloom was unserviceable to me. Note the elevation of the optics above the boreline. Unfortunately I do not appear to have a picture of the guns with the iron sights flipped up to show the relative height, but I assure you that in the case of the 1.5x optic you could see the irons through the scope, indicating that they were on at least similar planes.

The 16" gun wears the 3x, the 11.5" gun wears the 1.5x

[rob_s]

Something else you may find interesting, the view through both optics. I’ll leave it to you to figure out which is which.

[rob_s]

Another picture from back then. 1.5x in the Larue mount.

[RogueElephant]

@rob_s

The Trijicon factory, Larue, and ADM mounts will put the centerline of the Compact ACOG at the same centerline as the stock iron sights +/-. If, however, you mount the optic to the carryhandle as originally designed you will wind up with the optic 3"+ over the boreline. What the various mounts do is replicate the profile of the carryhandle channel but at a height such that mount+optic=optic centerline at ~2.5" above bore.

That’s exactly what I needed - all is clear, now. Thank you!

[RogueElephant]

@rob_s

Something else you may find interesting, the view through both optics. I’ll leave it to you to figure out which is which.

As you intended, they are remarkably similar. I’m guessing the one on the left is the 1.5x and the one one the right the 3x. I am basing that guess only on the reticules.