Trijicon RMR on a Glock. Absolute Cowitness or Lower 1/3?

[Powder_Keg]

I did a search to see if this was already discussed, but couldn't find anything. Please reply with a link to a thread if I missed it.

On my rifles, I go with a lower 1/3 cowitness. This will be my first RMR on a Glock. For those of you that have added a red dot to your handgun, do you prefer an absolute cowitness or a lower 1/3 cowitness. Any reason to why?

If it makes any difference I plan to run a plain black front and rear sights.

[BigBamBoo]

What do you intend to do with your pistol?

I have been looking at the RMR for a Glock 17 slide, but it will be used in carry optics division for USPSA and Steel shoots.

I have tried my buddy's Glock 34 with a RMR and co-witness sights. I found the iron sights distracting and actually slowed me down on targets as I was doing what I would do on my iron sighted pistols....focused on the front sight. Then I would try and focus on the target and get the dot on target. And all the while...there was the front sight.

So for a game gun, I would say no iron sights or just standard height sights.

If you plan on using it for defense, then co-witness would be smart.

I like using specific tools for specific jobs. So when I do out the slide together it will just have the factory sights that will not be used or seen with the dot.

Good luck.

.

[teflondog]

On my rifles, I go with lower 1/3 cowitness if my front sight is fixed. Therefore I would go with lower 1/3 cowitness on a Glock since the sights are fixed. It's less clutter in my sight picture.

[Powder_Keg]

What do you intend to do with your pistol?

I have tried my buddy's Glock 34 with a RMR and co-witness sights. I found the iron sights distracting and actually slowed me down on targets as I was doing what I would do on my iron sighted pistols....focused on the front sight. Then I would try and focus on the target and get the dot on target. And all the while...there was the front sight.

.

It will be mainly a range gun, but maybe at some point I'll use it for a local match.

I agree, my thoughts are the iron sights with absolute zero would be a distraction and block the view of the small window.

[Powder_Keg]

On my rifles, I go with lower 1/3 cowitness if my front sight is fixed. Therefore I would go with lower 1/3 cowitness on a Glock since the sights are fixed. It's less clutter in my sight picture.

That's what I am leaning towards, lower 1/3. I've read reviews that the iron sight will help guide the eyes to the red dot. I just don't want the iron sights to cover the target or take up more view then needed.

[mjmagee67]

On my Carry Optics USPSA gun....no irons. They are just too distracting.

[NorCalEmperor]

I run a lower 1/3 on both of my RDS hand guns. It is less clutter for your FOV and less distracting on your eyes when you bring your hand gun up on target. the RDS is your primary sighting option. your irons is secondary in case your primary fails. tech has evolved and many torture tests have been completed that prove many RDS can withstand the abuse. allow the clearest picture for your target as possible, lower 1/3 provides this.

dont forget... placement of the rear sight is important as well. as explained by Sage Dynamics.

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

[phreaticus]

Hi, this thread is very relevant to what I'm experiencing. I finally took the plunge into pistol red dots recently with an RM06 on a Jagerwerks milled G17. After shooting it for a few months with perfectly cowitnessed Trijicon suppressor height irons, in what appears to be the most popular configuration - I definitely now want to get the irons out of my field of view as much as possible. After just a bit of dryfire and methodical range training I find the single plane, target focus approach of the RMR to be an advantage across the board and I've experienced very little issues with finding the dot on presentation. My times on all drills are same or quicker as with irons.

As such, the more I shoot the setup, the more I find my cowitnessed irons to just be a distraction. I'd prefer to find a rear sight that is just barely tall enough to be seen over the RMR, even lower than 1/3 height, if possible. I'm actually considering to just leave the rear sight off completely - for backup purposes its actually pretty reasonable to just center front sight in the RMR frame and get solid A zone hits out to 10y no problem.

Question: what height rear sight are folks running to achieve lower 1/3 witness on Glock 17/19s with RMRs? (Milled slides, not MOS).

Thanks

[Powder_Keg]

Question: what height rear sight are folks running to achieve lower 1/3 witness on Glock 17/19s with RMRs? (Milled slides, not MOS).

Thanks

Thanks for the input. I sent my G34 slide to ATEi for the RMR cut, I requested a lower 1/3 cowitness. I asked for the Ameriglo all black sights. Not sure of the actual height of the front and rear sight, I'll measure and post pics when I get it back. I'm believe the depth of the RMR cut also comes into play if it's a 1/3 or absolute cowitness?

[cvigue]

That's what I am leaning towards, lower 1/3. I've read reviews that the iron sight will help guide the eyes to the red dot. I just don't want the iron sights to cover the target or take up more view then needed.

Both eyes open means the front sight won't really cover the target anyway.

[Powder_Keg]

Both eyes open means the front sight won't really cover the target anyway.

Not exactly true. With both eyes open, I've seen other people's setup with absolute cowitness and the red dot falls on the front sight. I want to avoid that. I want to keep the RMR window as clutter free as possible.

[phreaticus]

Not sure if this is useful to anyone, but here is some more info I've managed to glean w/regard to co-witnessing sights with RMR on Glock 17/19/34:

Some standard sizing refs
- G17/19 standard OEM rear sight: .256”, front: .165”
- Bottom of G17/19 dovetail slot to top of slide: .075”
- Height of Trijicon RMR (from bottom of Glock 17 rear dovetail sight slot to top of RMR base, where irons must look over): .305”
- Height of Trijicon RMR base, over top of slide: .230”
- Typical rear sight notch depths: .090-.120"

Tall sights for RMR setups:
(Note, these are full measurement from bottom of G17/19 dovetail slot to top edge of sight)

Absolute co-witness sizes:
- Ameriglo: .500" rear, .407" front
- Dawson: .495" rear, .485T front

Lower 1/3 co-witness iron sizes:
- Trijicon suppressor: .361" rear, .365 front
- Ameriglo: .394" rear, .315" front
- Dawson .395" rear, .390" front
- 10-8: .395” rear, .315” front

Obviously, there are others, but these are very popular ones with published specs.

@ Powder_Keg: I'm currently running a G17 with blacked out Trijicon suppressors 361/365 combo on G17 in lower 1/3 cw, which I think will be pretty similar to your G34 Ameriglo setup from ATEI. Enjoy it, and be sure to let us know how you're getting on.

For what it's worth, I recently shot an instructor buddy's G19 Leupold Deltapoint Pro which he has setup with the DPP adjustable rear iron sight module. It was adjusted so the rear iron was just barely visible above the red dot mount (much lower than a lower 1/3 co-witness, but still useable for backup). The uncluttered FOV and clarity of glass was way more comfortable than my RMR setup. I'd like to mimic that approach with my G17/RMR setup, if I can find a .330 ish rear sight... To be honest, I think G19 + DPP will be my next experiment...

Cheers

[cvigue]

Not exactly true. With both eyes open, I've seen other people's setup with absolute cowitness and the red dot falls on the front sight. I want to avoid that. I want to keep the RMR window as clutter free as possible.

Yeah you can see it but focus is on target anyway, so it's not an issue to me. I have several RMR dual-illums on several Glocks. No sweat, easy to shoot.

[phreaticus]

In case this thread is still of interest for like minded folks...

Personally, I subscribe to the "purist" philosophy on pistol red dots - key benefit & design thesis of red dot concept is to be 100% threat/target focused; irons are relegated to emergency backup only. This is how we've been using red dots on rifles for years...

So, on the quest for most uncluttered RMR window as possible, while still having a useful iron backup setup in case the optic/battery fails, it's been suggested by some sources that one can run a suppressor iron sight up front, and simply remove the rear iron sight altogether. In case of red dot failure, one simply centers front site within the RMR frame and it's claimed that one can shoot fairly accurately this way.

So, I finally got around to trying this setup today. Glock 17 with RM06 and Trijicon suppressor front iron night sight only (removed Trijicon suppressor rear iron sight, which previously gave me a lower 1/3 cowitness).

Results were a very clear win - without the rear iron sight, the RMR optic sight picture is much

[cvigue]

Results were a very clear win - without the rear iron sight, the RMR optic sight picture is much cleaner, making initial acquisition of the dot on draw/presentation & under rapid fire - much easier. I think this clean FOV is why some folks prefer the Delta Points over RMRs...

I initially sighted my G20 RMR in before I inserted the rear sight, and I admit, it was nice. I've been thinking to get my next slide machined as a 'race' cut where they set the RMR further back and cut away the rear dovetail, and just run it with a black iron front.