1/3rd or Full Co Witness Sight.

[Rockrivr1]

I just installed a Sparc on my M4 clone and I’ve gone back and forth on whether to install it with the 1/3rd co witness mount or the Full co witness mount. The sights are Magpul flip up sights so I’m thinking the 1/3rd might work better, but not sure

What do you prefer and what am I missing between the two?

 

[Mtn_Guy]

if I’m co-witnessing back up irons and a red dot, I prefer absolute co-witness. Then the red dot housing becomes a giant rear peep sight, and I only need front post unless I’m looking at longer target engagements or precise shots

My $0.02 as they say… comes down to personal preference… if you’re running a fixed front sight, lots of guys prefer lower 1/3 so the front sight post doesn’t obstruct the sight picture of the primary optic. Since I run MBUS Pros, they are flipped down 99.9% of the time.

On my LPVOs, I don’t worry about it at all… the eye relief on the optic and magnification make the backup up irons near useless for me, so if the primary optic fails, I would plan to remove with the QDs and just run the backup irons

 

[CMEBoston]

1/3 if the rifle has a fixed front sight, absolute with flip up sights is my preference.

 

[Rockrivr1]

if I’m co-witnessing back up irons and a red dot, I prefer absolute co-witness. Then the red dot housing becomes a giant rear peep sight, and I only need front post unless I’m looking at longer target engagements or precise shots

My $0.02 as they say… comes down to personal preference… if you’re running a fixed front sight, lots of guys prefer lower 1/3 so the front sight post doesn’t obstruct the sight picture of the primary optic. Since I run MBUS Pros, they are flipped down 99.9% of the time.

On my LPVOs, I don’t worry about it at all… the eye relief on the optic and magnification make the backup up irons near useless for me, so if the primary optic fails, I would plan to remove with the QDs and just run the backup irons

Good points. I'm thinking I may change the setup to full Co Witness.

 

[mav]

1/3 if the rifle has a fixed front sight, absolute with flip up sights is my preference.

This. ^

You can also avoid the whole co-witness thing if you go with offset irons. I do this on my rifles with magnified optics that are higher than 1X and/or don't have QR mounts. My VCOG is 1-8X works as a red dot at 1X, and has a QR mount, so no need for offset BUIS. I have flip ups that I will likely never need/use in that case. My 3-9x Trijicon on a Leupold fixed scope mount has offsets BUIS for close in engagement, zeroed at 50/200 like the rest of my BUIS.

 

[StevieP]

I like how my AR is configured. Backup Iron sites & Vortex red/green dot site. the dot is 1/3 co-witness w/ the BUIS.

I don't know all the benefits of one vs the other, but it seems to me with the 1/3 co-witness, there's more area above the sights/dot to see more stuff.

 

[Supermoto]

Put the dot at the height that is most comfortable for you to shoot at, that is the more important issue.

 

[F2386]

Absolute co-witness is great if you really like to snug up your cheek weld. I find my head is usually cranked a bit to the side in order to get a good sight picture though. My neck strains a bit too if I hold it for too long, especially with gear on. Nowadays people are pushing for higher mounts, even higher than 1/3rd co-witness.

Absolute co-witness - 1.40"
1/3rd co-witness - 1.60"

Below are popular mounts that are considered among the best in terms of quality and build. From what I can tell, the consensus is that higher mounts allow for a more natural straight up and down stance and cheek weld. They might not be ideal for going prone though.

Badger Conditon One - 1.54", 1.70" or 1.93"
Geissele Super Precision - 1 40", 1.60", 1.93"
Scalarworks LEAP/01 - 1.42", 1.57", 1.93"
Unity FAST Micro - 2.26"

I personally have a Badger CO for my LPVO at 1.70" and a Unity FAST Micro for my RDS at 2.26". I also run nvgs so the 2.26" helps with clearance when passive aiming. I don't think I could ever go back to absolute co-witness. Everyone's anatomy is a bit different though so it's worth testing out what works for you and what doesn't.

 

[Bodhisattva]

I’ve always like the 1/3 option. Gives a better heads up sight pic.

A buddy shoots a 1.93 mount, it’s a little too tall for my liking.

 

[TheGreekFreak]

Prefer absolute with flip up sights.