Home Forums Hunting & Shooting Hunting Optics AR-15 flat top, 3-9x40mm does not clear the front iron sight?

As title states, I have a flat top AR that has a standard front iron sight, and a rear flip up iron sight. For several reasons, I'd like to see if I can get a scope mounted on the upper, without removing the front sight system (in other words, replacing the front sight with a gas block.)

So I grabbed a piece of junk scope from my .22 with a 1'' tube, and borrowed these rings from a friend to mock up this scope installation. Rings are 1'' tall from top of rail to the bottom of the scope tube. So the center of the scope is about 1.5'' above the rail. Needs to go another 1'' or 1.5'', to clear the front sight it looks like so that would make like a 3'' tall scope ring? No combination of riser and rings reach that high that I can find? I can find a 0.75'' rail riser, and 1'' rings. But from my photo below, I don't think the additional 3/4'' will be enough. So without replacing the front sights with a gas block, what would you guys do to put a scope on this gun? Am I SOL?



Main problem is, this AR has a normal front sight and not a gas block instead. But, I'm just trying to get a scope on it for kicks, cheaply. Might help me test some loads, might not. Might use the scope for a soon upcoming Pdog trip, might not. This project won't see any real money spent on it. But if I can get a scope on it, effective and cheap, I would like to. If I need to remove the rear sight to use the scope I don't care, but looks like that won't be a concern once I'm tall enough to clear the front sight.

Any help on mounts to use? I do understand that such a high scope mount is not ideal compared to one closer to the bore of the rifle.

I haven't had any issue with front sight post using 1.5" tall Leupold rings,


or a Burris PEPR mount,



or this inexpensive Weaver riser block,


Looks like your carbine length system puts the front sight post a lot closer, but if you use 1.5" tall rings, or a proper AR15 mount, it should put your scope high enough that you can scoot it back a bit and the folding rear sight will fit below the ocular bell.

I'm guessing the scope is a low power model?
Ignore the front sight. It's not a problem. You'll either cowitness with it if it's a 1x scope, or it will disappear if you have a higher magnification scope.

If you want to use the scope forward and be able to cowitness with irons, you'll need a long eye relief model to clear the rear sight, with at least 5"+ of eye relief.
Look into a gooseneck mount of some sort, rather than the rings.
Using a normal eye relief scope as a primary, with just a folding BUIS under it (and no cowitness) is much easier, but would require a low profile BUIS.
My Yankee Hill folding sight won't clear even the small ocular on my Weaver 1-3x, unless absurdly high rings are used, or the scope is mounted further forward than its eye relief allows for. A low profile magpul BUIS might work with normal height rings though.

Noting the pictures above, I didn't realize that you could let the front sight be within the objective lens and still get away with it. I mocked up the scope last night, looked at it and said a four letter word. Didn't know any better, then started asking questions!

Since this rifle will not be dedicated to scope use, I think I'll go the route of a riser block, and the Burris "high" zee rings. That way I can use the rings with more flexibility on other guns.

Thanks guys.

i have a ar15 with the a2 front site and can not see the site in the scope. i tried 2 lower powered ar15 scopes and the site showed in both. i wouldn't put a low power scope on a 223 varmint rifle and i do not want one on my ar15. the scope that i'm useing now is a 2.5x10x40.

you can always do what my buddy did to his,get the dremel out and cut the tower site off at the base. smooth it up with a grinder then paint the bare metal. they don't look bad like that and if you are not going to use ,what the heck.