I just acquired a Rock River 6.8 spec and am now trying to decide what optics to put on it. The "problem" is that the rifle while it has a flat rail on the rear has a standard perm mounted front AR site. Can an optic be mounted high enough to over look the standard site or should it just co-witness? OR remove the front sight and install a gas block rail. Thanks for any advice in advance.
Question on AR Optics vs standard sight.
- Thread starter Sulaco2
- Start date
While many will tell you they "don't see the front sight" in the scope, I do see the front sight post when using lower X scopes. I find it a little distracting but not enough to go to the trouble to change the gas block. In the past, I'd just Dremel the post off and give the bare metal a coat of black paint but the market is full of gas blocks now.
I'd suggest just trying it the way it is and make up your mind later. Definitely don't try to mount your scope high enough to "see over" the front sight. That will be uncomfortable to shoot and deny you any sort of cheekweld.
I'd suggest just trying it the way it is and make up your mind later. Definitely don't try to mount your scope high enough to "see over" the front sight. That will be uncomfortable to shoot and deny you any sort of cheekweld.
I agree with what Mobuck said. Fixed FSBs aren't great for magnified optics.
However, when it comes to unmagnified red dot sights, you don't even notice the post. Just focus on the target through the dot, and it is like the front sight isn't even there. I prefer absolute co-witness with red dots, so I can get cheek weld.
All my scoped rifles have folding front sights, and all my rifles with red dots have fixed FSBs.
However, when it comes to unmagnified red dot sights, you don't even notice the post. Just focus on the target through the dot, and it is like the front sight isn't even there. I prefer absolute co-witness with red dots, so I can get cheek weld.
All my scoped rifles have folding front sights, and all my rifles with red dots have fixed FSBs.
BillyJack3
New member
Are you considering magnified or non-magnified? If magnified, you will "ghost" out your FSB when you magnify over 4x. With a red dot, you will likely adjust your cheek weld and the red dot will float above the front sight. I have a couple red dots with a FSB and don't even realize they are there. Lower 3rd co-witness.
Mag or optics?
I think I am going to go with a non mag optic red dot like the military style Vortex. I had one on another AR15 with no sights but flat rails and really liked it after putting on folding front and rear (MaTech) sights. I just got a flat rail upper for the Rock River in .556 and it is sporting right side off set folding sights and will get the EoTech for a set up. The 6.8 spec was a little more problematic with the half flat rail on the rear and FSB mounted up front. I guess I will mount the Vortex and take the Eo out to the range and try them with the FSB still mounted and see what I see. Hope it works I don't want to remove the FSB really...Thanks for all the info guys.
I think I am going to go with a non mag optic red dot like the military style Vortex. I had one on another AR15 with no sights but flat rails and really liked it after putting on folding front and rear (MaTech) sights. I just got a flat rail upper for the Rock River in .556 and it is sporting right side off set folding sights and will get the EoTech for a set up. The 6.8 spec was a little more problematic with the half flat rail on the rear and FSB mounted up front. I guess I will mount the Vortex and take the Eo out to the range and try them with the FSB still mounted and see what I see. Hope it works I don't want to remove the FSB really...Thanks for all the info guys.
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noonesshowmonkey
New member
For non-magnified optics, there are two common mounting methods:
Absolute Co-Witness - the aimpoint rests on top of the front sight post, using the same cheek weld and point of aim.
Lower 1/3rd Co-Witness - the optic aim point floats above the iron sights, which occupy the lower third of the viewing aperture. To fire with iron sights requires a lowered cheek weld to pick up the front sight post through the rear right.
Do a bit of research online, and you can quickly find riser mounts for red dot and EOTech sights that will accommodate either setup.
Fixed FSB for magnified optics can cause ghosting, but again, a sufficiently tall riser can get you past this problem. What you will be dealing with, instead, is height-over-bore. This is a solvable problem, but will impact how your ballistics tabling and scope zero work together.
Absolute Co-Witness - the aimpoint rests on top of the front sight post, using the same cheek weld and point of aim.
Lower 1/3rd Co-Witness - the optic aim point floats above the iron sights, which occupy the lower third of the viewing aperture. To fire with iron sights requires a lowered cheek weld to pick up the front sight post through the rear right.
Do a bit of research online, and you can quickly find riser mounts for red dot and EOTech sights that will accommodate either setup.
Fixed FSB for magnified optics can cause ghosting, but again, a sufficiently tall riser can get you past this problem. What you will be dealing with, instead, is height-over-bore. This is a solvable problem, but will impact how your ballistics tabling and scope zero work together.