Does it bother you when the fixed front sight on your AR rifle gets in the way of your sight picture while aiming through a low mounted optic?
While this problem exists for AR rifles with the removable fixed front sight and standard A2 fixed front sights, there are ways around it to eliminate the front sight post optic interference and they apply to other rifle systems too.
What has changed to the AR15 top receiver ? - As the AR15 rifle platform has evolved over time, the carry handle A2 and A3 top receiver model days are over. Now the A3 and A4 style flat top receivers allow the shooter to mount any optic accessories via M1913 picatinny rail with tons of flexibility.
Here in this article, first, let's briefly talk about sight why co-witness is important. Then we will show a few solutions for anyone that wants to eliminate the fixed front sight interference while mounting a scope on their ARs.
- Change To A Flip Up Front Sight - Just tuck it away! A flip up front sight is the easiest way to deal with front sight post interference when looking through an optic. You get the benefits of sight co-witness when needed, and just fold it up when not needed.
A free float rail system is required, please check out these rail handguards here
- Use Offset Sights - Mount an angled offset red dot on the top receiver. The shooter can simply tilt the rifle and aim without the A2 front sight getting in the way
- Raise Optic Height - Raise the optic height to clear the front sight post out of the way as much as possible using a 1/3rd co-witness mount or an riser mount.
- Use Magnified Optic - When using a magnified rifle scope, the front sight post does fade away when magnification increases and it will not get in the way of the sight picture
- Piggyback Red Dot Setup - This is similar to using an offset sight while the reflex sight is mounted on top of a magnified scope to raise the height, which is popular for Trijicon ACOG and other magnified scopes. However, this is not the most common setup and can be expensive.
Hope that helps!
Do You Need Co-Witness Sight Setup?
Why Is Co-Witness Useful ? - Co-Witness between the optic reticle and the front sight post gives the shooter the following benefits:
- Use as backup sighting system in the event of optic failure
- Use front sight post as the offset aiming reference point
- Serves as a reference point for zeroing reflex & holographic sights (Only if iron sights are already zeroed)
When is it not neccessary? - Co-witnessing the front sight can be annoying for the following reasons:
- Front sight post is generally bigger than a 2 or 1 MOA size reflex sight reticle that blocks the bottom half of the sight picture, and sometimes obscures overall field of view for target ID during day and night.
- As optic durability and reliability have significantly improved in the recent years, the need for back up iron is almost rare unless optic battery dies
When To Use Absolute Co-Witness?
Absolute Co-Witness optic mounts are the least popular on AR15 rifles because it doesn't allow proper cheek weld for most people and it sits the optic way too low on the rifle.
A absolute co-witness height only works if the top receiver already sits as high as a 1/3rd co-witness and the cheek weld position is perfect like AKs and
When To Use 1/3rd Or Taller Co-Witness Optic Mount?
Better Clearance For NV Goggles -This also aids anyone who wears bulky safety glasses and a pair of night vision goggles.
Better Reticle Clearance - Having the reticle sitting above the front sight post provides a clean field of view that isn't obstructing the sight picture for zeroing and target assessment down range.