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NorCalRefuge 01-13-2021 9:02 AM

RDS + Magnifier + BUIS Placement
I know this has come up before... just looking for fresh perspectives.

I'm using a magnifier for the first time behind a RDS. The issue is, of course, eye relief.

My current arrangement is micro RDS, followed by the magnifier, followed by my rear BUIS. The magnifier is one of the newer "micro" types, with decent eye relief but due to it's shorter size and my normal LOP on my adjustable stock, I'm finding I get a ton of "scope shadow" in my viewport.

I do not want to remove my BUIS, and the magnifier will likely not be mounted most of the time - but I want to reserve rail space for when I do want it without losing my zero on either the BUIS or RDS.

I'm considering moving the rear BUIS to be in between the RDS and the magnifier, as there is plenty of space for it to fold down there (due to the micro magnifier and micro RDS). My front BUIS is right behind the muzzle, since I'm running a full length rail - so I think my sight radius is fine with this configuration.

I have seen some competition folks run their BUIS in front of their RDS even... but in my particular case I do enjoy my RDS being as far forward on the receiver as possible.

Thoughts on this configuration? Looking for pro's, con's, and some experienced insights. :confused:

Full Clip 01-13-2021 9:06 AM

Buy a quality RDS and you'll never need irons.

FeuerFrei 01-13-2021 9:39 AM

If you cannot get satisfaction with your current sight arrangement then consider dumping your magnifier or invest in a continuous monolithic rail thet will provide you more uninterrupted real estate to plant your optics.

Using a smaller foot print rear buis that takes up less room is an option too.

Musical chairs with optics is a pain in the balls.

NorCalRefuge 01-13-2021 9:54 AM

Thanks for the input so far!

The BUIS are mbus pro's, which are fairly small already. Currently the rear buis is set on the very first rail slot, so it cannot be moved any further backwards.

The main issue is I need to move the magnifier further back, closer to my head, but cannot due to the BUIS being in the way.

There's plenty of room for the mbus pro rear to fold completely flat when in between the mag and rds... just unsure if that's a good idea or not.

Not really interested in ditching any component of this setup... mostly looking for advice from others that have run a setup similar to this. Besides it looking funny with the BUIS not mounted in the rear... any problems here?

Here's what I'm thinking of doing:

teflondog 01-13-2021 10:07 AM

That's a very short magnifier. I think you have 2 options with your setup:

1. Remove the rear BUIS and move the magnifier further back
2. Collapse your stock and get used to shooting NTCH

pratchett 01-13-2021 11:38 AM

Yeah, this is an individual biomechanics issue for sure. LOP and eye relief are on a bell curve, and you just happen to fall outside of the bell. For your specific case - I would not recommend this generally speaking - yes, I'd swap the placement of the BUIS and the magnifier. It'll compromise your ability to use your BUIS at longer ranges for precision by an unknown but likely insignificant amount but let us know how it goes.

If you decide to keep it there you may get weird looks or comments from Tactical Kerflufflers who believe in The Right Way, but who cares?

enorbit3 01-13-2021 11:42 AM

i think i saw a video from t rex arms where lucas puts the rear bus in front of the optic. let me see if i can find the link

ETA: here is the link 8 min mark

HKAllTheThings 01-13-2021 11:54 AM

No issues with moving it in front of your magnifier outside of losing some sight radius. It'll be a little harder to find the front sight since it's further away from your eye but it will work fine for the distances that you typically need to use backup irons anyways.

NorCalRefuge 01-13-2021 1:21 PM

Good advice from everyone, thanks!

I'm going to give it a shot. It'll look funny, particularly with the magnifier removed... but if it gets me into the sweet spot for the eye box, I'll be extremely happy.

I'll report back results!

HooYah 01-13-2021 1:44 PM

Sell that entire Chinesium setup, get a T2 and call it a day. :cool:

NorCalRefuge 01-13-2021 2:00 PM


Originally Posted by HooYah (Post 25313657)
Sell that entire Chinesium setup, get a T2 and call it a day. :cool:

Ah yes, I didn't realize T2's came with built in magnification these days... :facepalm:

anthracite 01-13-2021 5:16 PM

Does a shorter magnifier (in this case “micro”) create more scope shadow than longer traditional sized magnifiers?

New to magnifiers.

NorCalRefuge 01-14-2021 2:12 PM


Originally Posted by anthracite (Post 25314630)
Does a shorter magnifier (in this case “micro”) create more scope shadow than longer traditional sized magnifiers?

New to magnifiers.

No, not necessarily. Many of these "micro" magnifiers have excellent eye relief, when compared to the normal sized magnifiers...

However, since the micros are shorter in length, and since eye relief is measured starting from the end of the eye piece, a lot of the eye relief advantage is "given up" with a micro, and results in your head needing to be in pretty much the same position as a regular magnifier would dictate in order to see clearly through the magnifier without a lot of scope shadow.

There are other advantages to the micro magnifiers, namely size and weight - which are the reasons most people choose them over a traditionally sized magnifier.

NorCalRefuge 01-14-2021 2:22 PM

OK, so after fiddling with it a bunch... I've come to realize I was "doing it wrong"!

I initially tried out my idea from above, which resulted in this:

This definitely worked fine, as far as being able to clearly see through the magnifier without any scope shadow. However, the QD release handle for the magnifier blocked the charging handle... and looked stupid as f**k. :facepalm:

So, that got me into looking at how I, personally, was doing things, and came to the conclusion my LOP was just plain wrong on an AR. I grew up shooting shotguns and other fixed stock rifles, so had become very comfortable with longer LOP. When I got into AR's, I just mimicked what felt natural... which as it turns out isn't good for running a magnifier!

I settled on about position 3 of my 6 position adjustable stock (previously was using position 5), moved the RDS back a few slots, and wholla:

I can now see through the magnifier perfectly, so long as I keep my head in the "sweet spot" for the eye box. I don't think it's terribly unreasonable to have to "get into" the scope/magnifier, so I think I'll be comfortable running things this way for a while.

In short, if you're having a tough time with a magnifier, re-examine your LOP and be willing to change how you do things. :D

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