A Reader Asks About AR-15 Scope Mounts And Front Sight Interference

Reader Joe asks:

I’m Interested in purchasing the VXR Patrol, but want to make sure that my front iron sight post will not be in the way. Will a standard PEPR mount work, or do I need something else? Note: I’m shooting a Smith & Wesson M&P15 Sport.

Excellent question, Joe . . .

Many ARs (including yours and mine) are sold with fixed A2 front sights even though most of us put scopes or reflex sights on them. Removable or folding front sights are ideal for scoped ARs, but fortunately A2 front sights aren’t much of an optical obstacle for properly-mounted scopes.

As you probably know, standard A3 flattop rails aren’t high enough for most scopes or red-dots to co-witness with iron sights. EOTech holographic sights are an exception, since they’re tall enough to co-witness right out of the box. Most other optics will require some kind of riser mount to keep you from looking straight at the rear of your front sight tower, but these riser mounts are readily available and affordable.

This photo shows the VX-R Patrol scope you’re considering, mounted on standard medium-height 30mm scope rings and a $10 UTG riser. This solution is heavy and ugly, but it works. You’ve already hit on a much more elegant solution: a combination riser mount like the PEPR.

Burris’s ‘Proper Eye Position Ready’ mount shown here is designed specifically for AR pattern rifles, and it uses an offset scope ring to move your tactical scope forward and out of your eye socket. The PEPR is a great mount for around $100, but it’s not the only choice.

Leupold (the source of all things good and holy where optics are concerned) sells this bomb-proof Mk. 2 Integral Mounting System for about $150. At the lower end of the market is the $60 Primary Arms Deluxe AR-15 Scope Mount pictured at the top of the article. It has no frills and certainly no name cachet, but it gets the job done: Foghorn and I both trust it.

Any of these raised/offset mounts will lift a scope high enough to use with a fixed A2 front sight tower. The VX-R Patrol’s line-of-sight won’t clear the front sight completely, but you can barely notice it. The front sight will be dimly visible  in the bottom 1/3 of the scope’s field of view at the lowest power (and blurred to near-invisibility), and I can’t notice it at all at higher magnification.

My own AR wears fixed A2 front sights and a VX-R Patrol on the Primary Arms mount, and it works perfectly for me. The PEPR is a great scope mount for the AR, and the combination should work perfectly for your M&P15 Sport as well.

One last tip: if you do decide to go with the VX-R Patrol, be sure to order the PEPR with 30mm  rings.


  1. avatar brigo05 says:

    Armalite makes great single piece scope mounts as well. ~$90

  2. avatar Chris says:

    You refered to Burris as “Bushnell” in your link there.

      1. avatar Chris Dumm says:

        I didn’t do it; nobody saw it; nobody can prove a thing. And then Dan fixed it.

  3. avatar DrewN says:

    I use GG&G one piece bolt action height mount combined with a GG&G scout type riser. This enables me to run my scopes on any of my platforms with just a small weight penalty. This enables me to get by with only two pieces of premium glass, a 3.5 x 10 and an 8.5 x 25, both Leupold Mk4 front focals with the TMR. I find transitioning between scopes more troublesome than rifles, plus it’s alot cheaper. If I have friends who want to shoot at the same time, I have a few “beaters” in qr rings that I’ve accumulated over the years.

    1. avatar Chris Dumm says:

      Do you have to re-zero when you move the scope from one gun to the other? I’d expect so, but if not that’s great.

  4. avatar Chad says:

    I bought my first AR last week. It’s an Olympic Arms 5.56 and it has a carry handle. If I want to put a red dot sight on an AR with a carry handle, what options do I have?

    1. avatar Rambeast says:


      This is what you will want, if you have an A-1 configuration upper. Personally, I have come to the conclusion that iron sights are the way to go. Scopes are nice, but not optimal. Remember K.I.S.S. (Keep It Simple Stupid) In a fast paced life and death scenario, scopes can get knocked off zero, covered in mud/grime/etc, lenses can be broken…but iron sights are king, unless you are almost legally blind.

  5. avatar Jamie in ND says:

    I have a PEPR on my Stag 6.8 that has a fixed front sight. The scope is a Nikon Prostaff & I have no problems with seeing the sight in my scope.

  6. avatar Mike G says:

    I put a Redfield Revolution with Nikon mounts on a M&P15 Sport. At 2x there was a faint shadow from the front sight that I was able to remove almost completely by moving the scope a small distance rearward.

  7. avatar Diego Martin says:

    Hey, thks for sharing! Very helpful info here as I recently got my first AR-15. Thks for your tips. Cheers!

  8. Hello i am kavin, its my first occasion to commenting
    anyplace, when i read this article i thought i could also make comment due to this brilliant piece of writing.

  9. avatar Drew says:

    Recently just bought a Weaver V-3 1-3×20 which looks similar to the VX-R Patrol. My question is would any of the recommended scope mounts listed above work just as well with my scope on the Smith and Wesson M&P sport?

  10. avatar Michael says:

    I have been searching for two hours on the web for an answer to this very question! Here it is as clear and succinct as I could wish. Many thanks.

  11. avatar Gregory says:

    I have a Vortex SPARC2 red dot. It comes with two risers, will it clear the front A2 sight on a Colt 6920, or will I need to get it up higher?

    1. avatar David says:

      The 2 risers will do absolute or lower 1/3 cowitness. I chose absolute on my 6920 and love the combination!!

  12. avatar Ira Burnbaum says:

    Can someone post or link to a photo of the field of view through a scope mounted to a rifle with front iron sights at various magnifications?

  13. avatar eric crayon says:

    I am using Nikon P-223 3-9×40 Mate BDC 600 for my Ar15 and I strongly recommend it . This scope is made with the .223 AR 15 in mind. Designed with a great consistent eye relief, the Nikon 3-9×40 Mate BDC 600 prevents brow injury for the shooter regardless of calibers being shot and extreme shooting angles. The scope also offers different reticles for different distances. Boasting a visible field of view of 600 yards, this scope is designed for distance shooting as well. The lens housing also offers recoil absorption, even when being fired repeatedly, the scope will give the shooter a clear field of view making for a better shooting experience. Waterproof and fog proof, this scope offers a great amount of durability. The scope itself is also sealed using o-ring technology and nitrogen gas filled lens chamber which allows for an even more durable and weatherproof scope. Though this scope is specifically designed for the .223 and the NATO 5.56 AR 15 rifles, it can be easily mounted to virtually any rifle small or large in caliber.

    1. avatar Roger French says:

      Eric Crayon, what mount did you use to mount your Nikon P-223 scope and does it clear the front sight?

  14. avatar Larry W says:

    Feedback/Thoughts/First hand Experience Question:

    Would like to mount either a Vortex Spitfire 3x prism scope or a Burris 332 on a Stag 9mm AR Platform firearm, any input of either of these two optics or other that might be worth pursuing.

    This is just for plinking close to medium ranges.

    Thanks In Advance

  15. I am looking for the explanation what is the significance of the number P-223. What is implied when a company produces a scope which has this number in the product title. Bushnell and Nikon both produce variants of p-223. I can understand and calculate the magnification power, exit pupil and lens diameter which are important numbers in understanding scope features. Its this strange number 223 associated with the scope I am looking for some explanation for. Anybody here would like to share some insights?

  16. avatar AR15 Scopes says:

    There are several scope mounts for AR 15 and this scope mounts to mount the scope at an offset angle to allow clearance for large objective lenses. I would recommend a number that are good for AR15

    Nikon Two Piece Rings

    High Profile ArmourTac 30mm Scope Mount

    Flat Top Offset One Piece QD Scope Mount with Quick Release Cam Locks 1913 Picatinny Rails

    TMS Flat Top 1 Piece Ring Mount Picatinny Rails.

    That is my list of AR-15 scopes mounts I would consider buying.

  17. avatar Shawn says:

    I get my Ruger 5.56 next week, what size riser y’all think I need to clear that ugly front sight post? 1″? Another question is I have a Hammers 2-7 long eye relief scope like for a shotgun or pistol, do you think the Ruger 5.56’s rail will allow me to mount it far enough forward to be usable? If not I have a red dot sight as well I could use but then my distance is limited by my eyesight.

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