Co-witness Red-Dot with suppressor-height sights?

[D K]

I’m shooting a P-10F with suppressor height sights, and looking to mill the slide for a red dot. I’m looking at the 509T, or possibly the EPS when it come out, but I like the selectable reticle of the 509T.

I‘ve noticed that none of the makers list the height of the dot, so how does one ensure the sight will have a dot high enough to be able to co-witness?

Would I need to buy the sight, determine if will be high enough, and add some kind of extension plate if it is too short?

 

[MCgrease08]

I’m shooting a P-10F with suppressor height sights, and looking to mill the slide for a red dot. I’m looking at the 509T, or possibly the EPS when it come out, but I like the selectable reticle of the 509T.

I‘ve noticed that none of the makers list the height of the dot, so how does one ensure the sight will have a dot high enough to be able to co-witness?

Would I need to buy the sight, determine if will be high enough, and add some kind of extension plate if it is too short?

You don't need to co-witness the dot to the front site. You want the red dot to work independent of the irons and vice versa. You only need to use the irons if the optic fails.

 

[Dean C.]

The above is truth, an absolute co-whitness totally defeats the purpose of a pistol RDS. Lower 1/3 is what you are looking for, when shooting I don't even look at my irons. Draw, present the pistol and the dot will be on target assuming you do your job correctly. If the dot goes down you just raise the gun slightly and bring the sights into your field of view

 

[D K]

To be honest, I didn’t watch the entire 11 minutes, but sounds like he was basically saying “hey dummy, don‘t just dial your dot elevation down to match your irons”.

Let me ask a different way - suppose my slide were milled down 1/8”, the (properly zeroed) red dot arrived at 1/4” above the upper plane of the slide, but the suppressor-height rear iron sight was 1/2” above the upper plane of the slide. In this hypothetical scenario, the dot would be obscured by the rear sight. Just throwing numbers out here, I haven’t measured my irons, nor do I have any idea of how high the typical dot would be.

Do I make the assumption that, regardless of milling and iron sight height, all handgun-sized red dots will zero at a point that is as high, or higher than suppressor-height sights?

 

[MCgrease08]

To be honest, I didn’t watch the entire 11 minutes, but sounds like he was basically saying “hey dummy, don‘t just dial your dot elevation down to match your irons”.

Let me ask a different way - suppose my slide were milled down 1/8”, the (properly zeroed) red dot arrived at 1/4” above the upper plane of the slide, but the suppressor-height rear iron sight was 1/2” above the upper plane of the slide. In this hypothetical scenario, the dot would be obscured by the rear sight. Just throwing numbers out here, I haven’t measured my irons, nor do I have any idea of how high the typical dot would be.

Do I make the assumption that, regardless of milling and iron sight height, all handgun-sized red dots will zero at a point that is as high, or higher than suppressor-height sights?

The reticle of the RDS is going to be well above 1/4" off the slide. Height over bore is somewhere in the neighborhood of 0.7-0.9". I hardly notice my iron sights when I shoot red dot pistols, especially not the rear site.

Watch the full video. Aaron Cowan explains it all pretty well. He is one of the most experienced and knowledgeable red dot pistol instructors you can find. He tests them all, has shot them all and helped give input on the design of many of them.

Bottom line is that you don't need to worry at all about your iron sites when you zero the dot. Sometimes people will put the dot on the front post when starting the zeroing process just as a frame of reference and to be sure they're on paper, but after that you adjust the position of the dot completely independent of the irons.

 

[AllenM]

I mill for a lot of RDO's and getting co witness is not hard most all of them will co witness with suppressor sights. Even the 509T

Did a new thing

Milled a Glock slide to direct mount a Holosun 509T even allows for co witness :)

www.indianagunowners.com

Just sayin...

 

[Tactically Fat]

To be honest, I didn’t watch the entire 11 minutes, but sounds like he was basically saying “hey dummy, don‘t just dial your dot elevation down to match your irons”.

You are remiss in not watching Aaron's videos.

He's amongst the pantheon of subject matter experts when it comes to MRDS on handguns. If you want good information on the subject - watch his videos. Seriously.

 

[Dean C.]

I just want to point out how humorous I find it that OP is going to drop $500~ at least between the optic and slide milling, but will not even watch a 11 minute video. Just like when people ask "is X brand of optic reliable" and they have no idea the White Paper exists.

I know I am probably deeper into pistol dots than most , but it's expensive and before I drop that kind of coin on something I research the crap out of it to make sure I get the most "bang for my buck".

 

[D K]

I just want to point out how humorous I find it that OP is going to drop $500~ at least between the optic and slide milling, but will not even watch a 11 minute video. Just like when people ask "is X brand of optic reliable" and they have no idea the White Paper exists.

I know I am probably deeper into pistol dots than most , but it's expensive and before I drop that kind of coin on something I research the crap out of it to make sure I get the most "bang for my buck".

Ah, same applies to those who chose to comment before reading all posts. Not unlike making a news story about a sound byte taken out of context.

I have now watched the remainder of the video, and as I expected, the conversation continues on to revolve around slaving a dot to an iron sight, which was clarified as not being the concern in the “OP’s“ second post.


MC, and AllenM thank you for your constuctive feedback, the information is appreciated. I’m good to go.

 

[cedartop]

I’m shooting a P-10F with suppressor height sights, and looking to mill the slide for a red dot. I’m looking at the 509T, or possibly the EPS when it come out, but I like the selectable reticle of the 509T.

I‘ve noticed that none of the makers list the height of the dot, so how does one ensure the sight will have a dot high enough to be able to co-witness?

Would I need to buy the sight, determine if will be high enough, and add some kind of extension plate if it is too short?

I have never looked at it from that position before. In my case I have always mounted whatever optic I wanted to try/use and then found the right sights to work with that. Really you want the lowest height you can get with your optic and milling is usually the answer for that. That being said I only have 3 pistols that are direct milled. A Gen3 G19 that was done in 2010, a Gen5 G19 that AllenM did a few years ago, and a Sig X-Compact. The Sig came with sights and optic already mounted and is ok. I set up my 2 Glocks so that the sights are just high enough to use through the window. All of my pistols with plates on them some have usable irons and some don't, it depends what there purpose is. I would think with the optic you are talking about, even with a direct mill it should be high enough to work with suppressor sights, but I can't say for sure because I have no first hand experience with that combo.

 

[cedartop]

I don't really know of this guy except for watching one of his previous videos where I got a great zero/warm up printable target, but he does a great job explaining things in this video. I would say it is in a more beginner friendly way than some I have seen that say essentially the same thing.

 

[AllenM]

I agree he does do a great job of going into detail that would benefit users new to RDO.
I probably use the term co witness wrong.
I am referring to the irons being backup sights. I will have to be mindful of that next time.

I liked the video, thanks for sharing

 

[WebSnyper]

I don't really know of this guy except for watching one of his previous videos where I got a great zero/warm up printable target, but he does a great job explaining things in this video. I would say it is in a more beginner friendly way than some I have seen that say essentially the same thing.

Thanks. I also checked out his other video on zeroing the red dot. I had real issues when I got mine last year as I was trying to slave the dot to the sights and exactly as was stated became very difficult to find the dot, lots of wasted optic real estate and quick frustration ensued. Need to start over and sight it in the proper way.