Rear BUIS: In front or behind optic?

[texasaggie2005]

Apologies if I missed this somewhere, but I couldn't find much.

I'm about to make the jump into a G19 with an RMR, and while I'm still debating direct mill or MOS, I have a question about direct milling options.

BUIS, in front or behind optic? Any reason to prefer either? Pro's con's? I've read elsewhere that putting the rear sight in front of the optic will keep it from obscuring the optic window / red dot and help protect the glass on the optic. That makes sense to me. But are there any downsides?


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[dontshakepandas]

I've had both, and prefer having the rear sight to the rear of the optic.

Having the iron in front of the optic does allow you to see the dot in the area that the rear sight would cover if it were behind the optic, but I've never even noticed that happening in actual use. It also allows you to use the rear sight to rack the slide against something instead of the optic if needed.

The downside to me was that it placed the optic further to the back of the slide, which when carried AIWB was further from the belt line. This caused the optic to print significantly more. Another downside to the optic behind the rear sight is that it could limit you from using some optics like the Trijicon SRO.

Having the optic in front of the rear sight solved the printing issue for me, and also makes actually using the BUIS a little bit easier.

There really isn't a wrong answer, just preference. You could go with the Agency AOS cut which should let you get different plates to try both out and see which you prefer.

[Wake27]

Also had both and prefer rear, though I don’t have a great explanation as to why.


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[David S.]

Have one of each. No preference.

I suppose one benefit of the aft position is longer sight radius. You didn’t ask, but I do prefer all black BUIS. I also prefer the trapezoidal Ameriglo rear. They seem to block less window area.

[JSGlock34]

If you have any interest in ever trying a SRO (as the RMR and SRO share a common footprint), go with a rear mount.

I think a rear mount may be more 'future proof', as I wouldn't be surprised if future RMR generations have more in common with the SRO, particularly access to the battery compartment. That's speculation on my part, of course.

[Chain]

caveat: I don't have a pistol with a red dot

This guy makes a good case for iron in front of dot:

https://www.youtube.com/watch?v=zrrlxEwUaRM

[YVK]

Have both, and my answer is "it depends" but generally, the conventional setup.
I conceal better with irons in front of the optic. The suppressor height rear sight prints like a mofo for me. I do think that there is also less visual clutter that way.
The conventional sight arrangement is considerably more practical and allows for "just the irons" setup, if your slide milling guy also sells cover plates.
The conventional sight arrangement also allows for an unconventional "best concealment compromise" which is not mounting the rear sight at all. There is no print from rear sight, optic is farther down towards the belt line, and there is no visual clutter. I've done that, filling the dovetail with a cut-down OEM plastic placeholder.

[Default.mp3]

caveat: I don't have a pistol with a red dot

This guy makes a good case for iron in front of dot:

https://www.youtube.com/watch?v=zrrlxEwUaRMThe argument that you'll end up using your irons as a crutch to acquire the dot if the sight is in the rear position seems to cater to the lowest denominator, and I remain totally unsold by that argument.

Older thread: https://pistol-forum.com/showthread.php?23231-Rear-Sight-in-front-of-RMR

[Darth_Uno]

Having the iron in front of the optic does allow you to see the dot in the area that the rear sight would cover if it were behind the optic, but I've never even noticed that happening in actual use.
It also allows you to use the rear sight to rack the slide against something instead of the optic if needed.
The downside to me was that it placed the optic further to the back of the slide, which when carried AIWB was further from the belt line. This caused the optic to print significantly more.
Another downside to the optic behind the rear sight is that it could limit you from using some optics like the Trijicon SRO.




All this. On the other hand, having the sight in front of the optic gives a you an unobstructed view of the window. That's about the only major plus that I can see, but some might very strongly prefer it.

[texasaggie2005]

I've had both, and prefer having the rear sight to the rear of the optic.

Having the iron in front of the optic does allow you to see the dot in the area that the rear sight would cover if it were behind the optic, but I've never even noticed that happening in actual use. It also allows you to use the rear sight to rack the slide against something instead of the optic if needed.

The downside to me was that it placed the optic further to the back of the slide, which when carried AIWB was further from the belt line. This caused the optic to print significantly more. Another downside to the optic behind the rear sight is that it could limit you from using some optics like the Trijicon SRO.

Having the optic in front of the rear sight solved the printing issue for me, and also makes actually using the BUIS a little bit easier.

There really isn't a wrong answer, just preference. You could go with the Agency AOS cut which should let you get different plates to try both out and see which you prefer.

Thanks for the input. Concealability will be key to me. I've recently lost ~25lbs, and concealing a G19 AIWB has gotten a lot more difficult.


Have both, and my answer is "it depends" but generally, the conventional setup.
I conceal better with irons in front of the optic. The suppressor height rear sight prints like a mofo for me. I do think that there is also less visual clutter that way.
The conventional sight arrangement is considerably more practical and allows for "just the irons" setup, if your slide milling guy also sells cover plates.
The conventional sight arrangement also allows for an unconventional "best concealment compromise" which is not mounting the rear sight at all. There is no print from rear sight, optic is farther down towards the belt line, and there is no visual clutter. I've done that, filling the dovetail with a cut-down OEM plastic placeholder.

Thanks!


The argument that you'll end up using your irons as a crutch to acquire the dot if the sight is in the rear position seems to cater to the lowest denominator, and I remain totally unsold by that argument.

Older thread: https://pistol-forum.com/showthread.php?23231-Rear-Sight-in-front-of-RMR

Of course there was a thread. Thanks for finding that.

[texasaggie2005]

If you have any interest in ever trying a SRO (as the RMR and SRO share a common footprint), go with a rear mount.

I think a rear mount may be more 'future proof', as I wouldn't be surprised if future RMR generations have more in common with the SRO, particularly access to the battery compartment. That's speculation on my part, of course.

Future proofing is certainly a concern. That is what is making a MOS + FCD OPF-G or an Agency cut very tempting.

But everything I read claims that direct mill is the most durable option.

[JSGlock34]

Future proofing is certainly a concern. That is what is making a MOS + FCD OPF-G or an Agency cut very tempting.

But everything I read claims that direct mill is the most durable option.

So I agree that direct mount is the best possible solution, but I've had optics fail in both MOS and direct milled guns. I do think the FCD and CHPWS mounts go a long way in narrowing the gap between custom milling and modular systems. A MOS pistol (or retrofitting a complete MOS slide) is the easiest entry into MRDS guns.

One of the appeals of the RMR footprint though is that the SRO is also an option. The nature of the SRO overhang prohibits putting the rear sight in front of the optic. I'm not entirely positive, but I think the SRO overhang is a result of the top loading battery design. I suspect a future RMR may use a similar overhang to provide for access to the battery from the top. Again, that's entirely my speculation. But that would be enough for me to want the rear sight in the traditional location. My two cents.

[texasaggie2005]

Well, I found the last G19g5 in my zip code, literally. Interesting model too, Glock threaded barrel, suppressor sights (Ameriglo?) and the usual Glock stuff.

Looks like I'm going direct mill or AOS.

https://imgur.com/OBSP7MS.jpg

[Mirolynmonbro]

Following this. I'm sending my slide and dot to primary Machine and I'm undecided on rear sight placement

[theJanitor]

I had a RMR on my 1911 before I had one direct milled onto my g17. I originally went with irons-behind to keep everything looking the same. What I then found was that I indexed the glock the best by hooking my thumb on the rear sight when getting a grip on the gun from the AIWB position. I will likely maintain that arrangement from here, on out