AR-15 red dot scope question


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Incormb0
March 10, 2012, 06:32 PM
Hi everybody,
I have a flat top AR with a fixed front post sight purchased from Palmetto State Armory. My questions are: Do I need a riser on the flat top upper receiver for a red dot scope? Should I align the red dot with the front post? What preference do you have? I have read a little about co-witness, but I am just starting out with my first AR build.

Thanks for the help,
incormb0

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Sky
March 10, 2012, 07:05 PM
Hummm if I understand your question properly....it will probably depend on what red dot you have. My Eotech just mounted and co-witnessed and the Aimpoint has a Larue mount that did the same. The vortex Sparc and Strikefire came with their own mounts and the Sparc had three if I remember correctly. The other dots I have are mounted on different firearms but seem like they would co-witness just fine. Tell us what kind of Red Dot you have and maybe we can go from there. All my Red Dots have the dot appear to be sitting right on top the front sight except for the GSG-5 which is considerably above the front post.

aubie515
March 10, 2012, 07:59 PM
It depends on if you want absolute or 1/3 co witness. I personally use 1/3 co witness. I sold my Aimpoint T1 4moa version with Larue 660 mount.

I just got back into AR15s again and just ordered the latest T1 with 2MOA dot and Larue 660 mount. As you can tell...I'm fond of the T1 with LT 660 mount.

Slotback
March 10, 2012, 08:19 PM
What aubie said. It depends on what you want. Experiment with both absolute co witness and 1/3 co witness. See which one you prefer and run with it.

rcmodel
March 10, 2012, 09:18 PM
IMO: Mounted lower is better, regardless of what the co-witness turns out to be.

You can't get a good cheek weld if the red-dot is on a raiser wobbling around way up there above the normal line of sight with your face planted on the stock.

rc

greyling22
March 11, 2012, 10:20 AM
my first AR I got had a flat top and no front sight. I put a red do on there thinking the old mantra, lower is better. What I found out was that I couldn't get my head down low enough to see through the dot scope and had to get a 1" riser. Not to clear sights or co-witness, but just to put the dot in the proper position to see through. There is a reason AR sights are so high off the gun, there is no drop to the stock like on a normal rifle.

Sky
March 11, 2012, 10:26 AM
my first AR I got had a flat top and no front sight. I put a red do on there thinking the old mantra, lower is better. What I found out was that I couldn't get my head down low enough to see through the dot scope and had to get a 1" riser. Not to clear sights or co-witness, but just to put the dot in the proper position to see through. There is a reason AR sights are so high off the gun, there is not drop to the stock like on a normal rifle.

Agree, comfort and cheek weld are all part of the package.

briansmithwins
March 11, 2012, 12:07 PM
For that set up I'd get this and be done:

http://www.laruetactical.com/aimpoint-micro-t-1-2moam4-qd-mount-combo

and this for backup:

http://www.laruetactical.com/larue-tactical-buis-qd-lt-103

BSW

Sergeant Sabre
March 11, 2012, 05:02 PM
The forums I've linked below will be much more helpful to you than this one.

In short: with a red dot, the dot = the point of impact. That's regardless of where it is in the tube. That means you don't need to align it with anything. You don't need a riser. Keep both eyes open and you will "see through" the front sight. Ignore it.

www.ar15.com

www.m4carbine.net

briansmithwins
March 11, 2012, 05:22 PM
Looking though the front sight can be done, but most people would find that would get old pretty darn fast.

BSW

The War Wagon
March 11, 2012, 05:33 PM
I prefer an absolute co-witness myself. I do NOT like looking at 2 different aiming points (red dot, front sight post) and GUESSING where the bullet MIGHT impact - it gives me headaches.

Some folks however, DO prefer a lower third co-witness. You'll simply need to try both and see. And depending ON your mount, you may - or may NOT - need a riser. I run ADM mounts personally - they make them in both absolute and 1/3 co-witness varieties, for all the most popular electro-optics. NO riser necessary.

wally
March 11, 2012, 05:51 PM
If your red dot is good, its parallax-free enough for co-witness or lower 1/3rd to purely be a matter of personal preference.

I prefer the lower 1/3 co-witness but not strongly. With a red dot I tend to look "over the irons" when using the red dot and lower 1/3 seems to make this more "centered" when using the dot.

You do need to remember that with irons you focus on the front sight with blur on the rear and target, with a red dot you look "through the dot" and focus your vision on the target -- keeping both eyes open is where the red dot really shows its speed.

MistWolf
March 11, 2012, 07:15 PM
This is what I'm using. The mount and riser came with the Aimpoint H2 I purchased from PSA. If I recall, the riser & mount came from Aimpoint with the sight. I'm not sure if it's absolute or 1/3, all I know is that it works, it's fast and consistent, even when my cheek weld is off. The parallax free claim holds up under actual use
http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/Carbine_H1.jpg

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