Cx4 Red Dot Recommendations?

[Guest Katana]

I'm trying to get some opinions from Cx4 owners on a good, reliable, red dot scope. I'd love to find one that co-witnesses with the iron sights.

I had originally had my heart set on EOTech 512, but after doing some research, it looks like I can't make it co-witness, and since the base is so wide, it may get in the way when trying to charge the gun.

Anyone found a good alternative, preferably in the $400 or less price range? I've been reading some good things about the Burris Fastfire, but I'd like some opinions on any that you may have experience with.

I need something reliable, as I'm currently planning on making this my home defense go-to gun.

[Guest Lester Weevils]

Hi Katana

Maybe you want something tougher-built than what I'm currently using. Just reporting because it works.

When I got the CX4 had a 10 year old inexpensive BSA 40mm "barrel type" red dot. Had used the BSA for years and it hasn't failed yet, but haven't abused it. That same model is sold under many brand names.

It co-witnesses fine at about two-thirds down from the scope top. If I move my head up so the dot is centered in the display, it seems pointed very near the same place as if I move my head down so the dot shines right ontop of the front iron-sight blade.

Many of the inexpensive red dots have a 45 degree mirror and they approximately keep the point of aim in one axis regardless of where the dot is in the display, but they have a lot of drift in the other axis if you let the dot get out of the center of the display. Depending whether the mirror and LED is shining from the side, versus some other model where the LED is shining from the top or bottom-- One configuration has bad parallax left-to-right but not much parallax up-to-down. The other configuration is insensitive to left-right parallax but has a lot of up-down parallax error.

I compared two different cheap red dots, one with the LED on the bottom and another with the LED on the side, and they both seemed to follow the rule described above. Maybe my theory is all wrong. It is just what I figured out by putting the sights in a bench vise, aiming at a dot on the shop wall, and moving my head around to see which way the red dot drifts off target if the dot is not centered in the display.

On a pistol or shotgun with the inexpensive red dots of this design, your best bet is to keep the dot right in the middle of the display.

The more-expensive holographic sights do not have much parallax problems if the dot is not exactly in the center.

For co-witness unless a cheap red dot is short enough that the center of the barrel lines up with the center of the iron sights, you would want the red dot that is parallax-insensitive in the up-down axis. So that the dot stays aimed about the same place whether looking high thru the center of the red dot barrel or looking low thru the back iron peepsight. That old BSA sight is oriented the proper way so that it is parallax-insensitive in the up-down axis.

Maybe a smaller sight would be better. The reason the BSA sight is mounted so far forward in this picture-- The 40mm sight is fat enough that it can get in the way of the charging handle if mounted farther back. On the other hand I was surprised that the red dot works great mounted far forward like that. It looks kinda odd but works fine.

The cute newer 20 or 25 mm mini red dots like the Sig and inexpensive Sig clones would be about half the height of the sight in my picture and may not get in the way of the charging handle. I have an $80 Konus sight that looks just like the Sig sight and seemed to work fine. I had it on a Ruger Mark II pistol and was going thru a phase where I couldn't shoot the Mark II worth a darn and took it off because I thought maybe the Konus was not holding center. But my shooting was about as bad with the Mark II iron sights so maybe there is nothing really wrong with the little Konus and it holds center fine. Just haven't got around to re-testing the Konus to find out if it is broken.

I'm not saying that a cheap barrel-type red dot would be ideal or tough enough for combat but it works. It has lasted a long time and I think I'm only on the second set of batteries. It uses the cheap little lithium disk batteries.

[Guest Katana]

Thank you for the reply Lester Weevils. First, let me say I love that MSAR.

But it looks like I'm going to go with the Burris Fastfire II for my red dot needs after I totally overhaul the internals in my carbine. I've decided to get all the Sierra Papa parts for my gun first, then I'll focus on a good combat sight.