How to Install the Burris PEPR AR-15 Scope Mount

The Burris PEPR Scope Mount for the AR-15 is one of the most popular, affordable, and robust mounting systems out there.  I run it on my competition AR combined with a TAC30 and below we’ll go over installing its big brother, the Burris MTAC.

Not sure what scope and mount combo yet?  Check out our Best AR-15 Scopes & Optics article first.

TAC30 in PEPR Mount
TAC30 in PEPR Mount

What You’ll Need

Tools for Installing PEPR
Tools for Installing PEPR

There’s a few necessary items to installing a new scope mount but also a couple of really nice-to-haves that will make installing easier, more accurate, and create a more robust system.

Necessary Items

You Should Get These

  • Wheeler Accurizing Torque Wrench ($40): This let’s you adjust the torque of the screws to make sure they are the correct amount and more importantly, that they are the same for each for a more consistent mount.
  • Blue Loctite ($6): This threadlocker strength will prevent the loosening of your screws due to recoil vibrations.

Nice to Haves

  • Wheeler Scope Leveling Tool ($16): If you don’t already have a bubble level, this two level system attaches to both the rifle and scope to take care of everything at once.
  • Wheeler Professional Reticle Leveling System ($40): When you want the professional option in mounting your scope.  Consider this for a high magnification or more expensive scope.
  • Magnetic Boresighter ($30): Helps you get your scope on target before finalizing at the range.
  • Gun Rest ($70): Helps keep your AR-15 upper steady and will also help later on when you zero your scope.  Not super necessary and you can get by with a bipod or a bunch of boxes/books.

How to Install the Burris PEPR Scope Mount

The name of the game is to get the horizontal and vertical axes of the scope to match up with the gun and also minimize inconsistencies in the torque of the screws.

  • Take apart your AR-15 and keep the upper
  • Position it with a gun rest or something else so it sits securely
AR-15 Upper in Gun Rest
AR-15 Upper in Gun Rest
  • Loosen the base of the PEPR Mount and lightly screw it to the Picatinny rails on top of the upper receiver with the offset facing the front of the barrel.  Don’t worry about exact placement since we’ll be moving it back and forth later.
PEPR Mount Front
PEPR Mount Front
  • Clean your scope and rings to make sure there’s nothing that will scratch your scope.
  • Put the scope on the bottom mounts (thinner tube facing the front) and choose the top half of the rings.  Unless you plan on putting another sight such as a red dot on top of your scope, go with the smooth rings for some snag and weight reduction.
  • Screw in the four corner screws lightly for each ring.  Make sure you can move the scope back and forth and rotate.  Also make sure to have some space between the scope rings and the middle of the scope which starts to round.  For example, A below is probably the closest I would want my rings to the center.
PEPR First Screws
PEPR First Screws
  • You might notice that gap between the rings will be slightly different…I wouldn’t worry about it unless you are super OCD and just want them to look the same.  If so, you can adjust them right now.
PEPR Mount Ring Gap
PEPR Mount Ring Gap
  • Now we’ll make finer adjustments to the scope placement for eye relief and possible backup iron sights (BUIS).  You can choose to move the entire mount+scope forward or backwards on the upper receiver rails.  And also to move the scope in the rings.  Use the same butt stock length you always use, and get a proper cheek weld when testing.  Yes, you’re going to have to attach the lower right now.
  • I found mine was too rearward initially and fine-tuned everything until I saw a full-sized sight picture through the scope with my regular cheek weld (and could use my BUIS).  I then take the mount off and add some of the Loctite to the large screws.
MTAC in PEPR Mount and BUIS, Too Rearward
MTAC in PEPR Mount and BUIS, Too Rearward
Eye Relief, outdoorlife
Eye Relief, outdoorlife
  • I like to push forward on the mount while I secure the two ring base screws to the prescribed 65-100 inch-lbs first using just my hand and then using the torque wrench.  This takes away any space that could cause the mount to move during recoil.
Push Forward on Mount, Vortex
Push Forward on Mount, Vortex
  • If you have the two level Wheeler System, you can skip these next few steps.
  • Find a thin target about 25 yards away that is completely vertical.  I’m using the wire of my wind chime.
Wire of Wind Chime
Wire of Wind Chime
  • Place the bubble level on the scope until the middle one is level, set the scope to the max, and look at your target.
PEPR Mount Bubble Leveled
PEPR Mount Bubble Leveled
  • You want the level to always be centered while the vertical axis of the scope matches with the vertical target.  It will take a couple tries of adjusting your scope and your rifle placement.  Apologies for the bad 4x picture.
PEPR Mount 4x
PEPR Mount 4x
MTAC View
MTAC View, 1x
  • If you do have the two level system, you don’t even need a target and can do everything in the comfort of your own home.  Just place one level on top of your scope and one level on the Picatinny base of your AR-15.  Once they are aligned…you are done!
Two Bubble Level Scope Mount System, Vortex
Two Bubble Level Scope Mount System, Vortex
  • No matter what bubble system, once the scope is level you want to start securing the screws.  My preference for the PEPR since it has 6 screws, is to put the two remaining middle screws in on both rings with a little bit of Loctite.  I set my Wheeler Torque Wrench to the recommended 20 lbs and screw those in.
PEPR Mount Loctite
PEPR Mount Loctite
  • Then I finish it off with Loctite and an alternating corner method for the remaining four screws on each side.
MTAC PEPR Final Loctite
MTAC PEPR Final Loctite
  • Do a final test of the leveling bubbles to make sure nothing shifted during the tightening.
  • I recommend bore-sighting before heading out to the range so you can at least get “on paper” accurate before final adjustments.  You can use the recommended magnetic boresighter or just look down the barrel from where the bolt carrier group (BCG) normally is at a target and adjust your scope until it reasonably meets the target.
Boresighting AR-15
Boresighting AR-15
  • Wait a day for the Loctite to cure and you’re ready to shoot and zero at the range!

Conclusion

There’s a couple ways of installing your PEPR scope mount for the AR, but even if you only have one bubble level, you’ll do fine.  How did your installation go?

 

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