what height or rings do i need to mount a scope on my ar so it will clear front sight???

Due to the AR15 design the optimum height for Optics is 1.4” above the upper receiver.  This is due to the Receiver Extension, otherwise known as the “Buffer Tube”, which does not have a drop at the comb like a conventional rifle. Based on this, Mounts and Rings that put the center of the optic at 1.4” give the best cheek weld.    Lower Mounts and Rings can be used, but this increases the chance of canting the rifle in order to see through the scope.  I’ve used rings as low as 1.185” to center and although they worked I ended up driving my cheek into the stock and had to be conscious not to cant he rifle.

Standard Rings can be used but due to the limited space available on the Upper Receiver you may not be able to obtain the proper eye relief.   Bridging the gap between the Upper and Handguard is not a good idea, most newer Free Float Handguards are rock solid and have anti-rotation devices but there’s always a chance it could rotate.  Free Float Handguards can also flex, scopes do not like to flex.  

Cantilever Mounts are by far the best choice for AR15’s.  They allow the Scope to extend over the Delta Ring giving you the ability to get the proper eye relief.  Using a true Monolithic Upper eliminates the need for Cantilever Mounts and Standard Rings will work fine but you still need to get the proper height.

Quick Detach Return to Zero Mounts and Rings are a personal preference…  I personally like the feature whether I need it or not.  I agree that it is not absolutely necessary, but the ability to remove the Optic for weapon maintenance / repair with-out losing Zero is a great option.  I hate getting bore cleaner on the lenses of my optics and with a QD mount I don’t have to worry about it.  Having the ability to have more than one optic for the same gun and switching between them with-out having to re-zero is well worth the extra cost of the QD design also.

Standard Rings can also return to zero as long as they are torqued to the same as when they were installed (usually 65 in pounds) but this means you either have to buy a pricey smaller Torque Wrench like a Seekonk or tote around a larger one.  Additionally, if you use Rings with Allen or Torx Head Screws you always run the risk of stripping the heads.  

To clear the front sight, they'd have to be like three inches tall. You install the scope behind the fsb. The scope cant focus on an object that close and it goes away.

let me dig for a pic........

As you can see in the pic, the scope is behind the front sight base. To get over it the scope rings would have to be ridiculously high. But like I said you cant see the front sight base. This scope is a Sightron SII 4-16x42. It's off my varmint gun. This 14.5" M4 usually has an Aimpoint on it. It is in a scope mount made by Larue called the LT-104. It's a one piece QD that cantilevers over the hand guard to move the scope forward enough to get the proper eye relief (see last pic). This is what cormorantslayer was talking about. With standard rings, the scope would be forced back by the short rail on the upper. I'm not positive on the hight of the LT-104 but it is very close to the 1.4" cormorantslayer mentioned (clears MBUS :)

playing around with iphone pics one day. sorry. best i could find. hope this helps.

what about using a riser????

by the way nice setup there clickbang

Some will use a cantilever riser to move the scope forward and higher with medium height standard rings. But this adds more fasteners to come loose, more unnecessary weight, and you are limited on quality QD options. And least of all, to me, it looks dewffy. Fewer parts and fasteners to fail or loosen, is better.



Thanks for the kind words.

Grab one of these and be happy the first time.

on the right side of the page there are 2 drop down menus.  Choose the size rings you need for the scope body with the top one.

If you don't care about Quick Detach Levers choose the VFZ option, it knocks $50.00 off the price.

+1 I love mine.

So let me get this straight.  No need to worry about the FSB showing up in the scope.  Right?  This has been a concern for me.  I don't want to look through my scope and see the fixed sight while looking through the tube.  Please confirm.

An Aimpiont or Eotech you would because of the zero magnification. But an optic with magnification can't focus on a object that close. With mine, there's no blur, dark spot, or any sort of difference in any way. I'll try to get a recital pic for you.

Aimpoiont with ARD killflash on a car length upper. The ML2 is in a Larue LT-150. The mount is designed to let you use the irons in the lower 1/3 of the optic when mounted. You can see the front sight base.



**this was not easy to do with an iphone**
The Sightron 4-16x42 is in a Larue LT-104 on the same car length upper. Pic is at four power, minimum setting. Fence is at 45 yards. At any magnification setting and any objective distance setting, the front sight base does not come into focus to the shooters eye. It really does disappear. That's all she wrote. End of story. There is no spoon. /thread/ Bde, bmh, bdo,bdme, That's all folks! Stay classy San Diego.



ETA- 33 post in one day? Stay out of the GD.