Learn how to properly mount a scope on an AR-15 with this beginner-friendly Brownells Tech Tip. Caleb walks through the complete process of mounting and leveling an LPVO optic using a cantilever scope mount, including proper eye relief setup, torque specs, scope leveling techniques, and common mistakes to avoid. Whether you just bought your first AR-15 or you’re upgrading your rifle with a new optic, this guide covers everything you need to confidently install your scope the right way.
In this video, we cover why AR-15 rifles require cantilever mounts, how to avoid bridging the receiver and handguard, proper ring placement, how to level your optic correctly using an Arisaka scope leveling tool, and how to bore sight your rifle before heading to the range. Caleb also explains torque specifications, scope ring alignment, and how improper mounting can affect accuracy.
Chapters:
00:00 Introduction
00:30 AR-15 Setup and Front Sight Considerations
01:03 Choosing the Right Scope and Mount
01:59 Why Cantilever Mounts Matter
03:30 Scope Ring Sizes and Mount Compatibility
04:07 Setting Eye Relief
05:55 Securing the Rifle in a Vise
06:18 Mount Installation and Torque Specs
08:25 Installing the Scope in the Rings
10:02 Proper Ring Placement
10:57 Equalizing Ring Gaps
12:44 Why Scope Leveling Matters
13:46 Common Scope Leveling Mistakes
14:52 Using the Arisaka Scope Leveler
17:13 Tightening and Torquing Ring Screws
19:49 Final Scope Alignment Check
20:10 Bore Sighting an AR-15
21:45 Final Thoughts
Products Featured:
Sig Tango MSR 1-4x LPVO
AR-15 Cantilever Scope Mount
Fix It Sticks Torque Driver
Arisaka Scope Leveler
Brownells AR-15 Vise Block
Mounting a scope on an AR-15 the right way is critical for accuracy, reliability, and comfort behind the rifle. This video explains proper optic mounting techniques for LPVOs, red dots with magnifiers, and traditional rifle scopes on AR-platform rifles.
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I dont have a torque…dang
Good tutorial, but of course half the tools used are out of stock.
Man, Brownells Has Certainly Come In Clutch!!
Please do videos in 4k
So the rear sight is trapped in there and is useless?
That's a nice machine you have back on the ether cabinet 👌
Most of the scopes I've mounted on a cantilever mount didn't allow me the clearance to fit my arisaka scope leveler under the bottom of the turret housing. Great video though
Where did Brownells find your DA??? You can't build AR's correctly and why on earth would you put flip-up sights on when the scope mount isn't QD!!! What… are you going to carry a 1/2 inch socket around everywhere you go???
Also you're a nit wit for not using thread locker like VC-3 or blue Loctite on your scope ring screws!!! I guess you can't fix STUPID!!! Good job messing things up as usual Caleb!!!
I'm one of those folks that just bought a new optic for the first time. Reading between the lines here…. does this mean once you have balanced the optic on the mount, it doesn't need to be rebalanced if you move it to another rifle? Does it just need to be re-zeroed and NOT rebalanced?
I give this video a five star rating. Nicely done.
Great video. Thank you.
Good Video…
RIP AERO! <3 I LOVE my mod 4 upper-receiver on my dont tread on me Anderson lower :..(
Just bought my 1st LPVO a ARKEN this video will come in handy 👍Thanks Caleb
Nice 👍🏻
You put it within your eye relief. I just saved you 20 minutes 😉
Really wish these scope makers would machine a housing that allows an ACOG-Style screw mount to be attached right to the bottom without any leveling BS. Also, no loctite?
I make sure the rifle is level. Then ck the level between rail and the mount. Then work the wedges. Snug rings to torque with the criss cross pattern, keeping tops equel gap. Then hang a plumb bob to make sure every thing level.
Watched this just to see if there's anything extra I haven't been doing. First leveling tool: Arisaka scope leveling tool. Ive been using that for over 7 years now, check. I use that for "almost close enough." Then I double-check that with scope bubble levels across the upper reciever and the top turret just to see if anything is not true with the mount, or the scope itself etc. Then Ill look through the scope in orientation to the rifle one more time just to make sure there's nothing off with the reticle. Then fully tighten to spec, This is a good video for someone new to get them going.
he should had showed how to with levels and check with plum line cause with my little knowledge seems how more people do it but i always enjoy his videos.
It’s not about the level of the rifle, it’s the level of the cross hair when you are shooting.
Always trust Caleb for the right way to do things. I recently leveled my first LPVO with bubble levels on the rail and turret, but I used the plumb bob and reticle projection method to check and it seemed okay. Now I want one of those Arisaka tools though, lol.
I’d love to get a great scope mount, but when you need a 1.93 height and vortex doesn’t make them, and those who do want $400 which is more than my LVPO, you have to do what you can with what’s out there. Don’t judge me too bad. It’s hard times out here!
This work it a tinpmann 22lr??
Great video, just one comment (and perhaps Mr. Caleb stated it but I missed the comment): I tend to adjust eye relief based on how I intend to use the firearm. Sitting, standing, or prone. For example, if I have a rifle I am going to use 90% of the time prone, I am not going to adjust eye relief based on it shouldered when standing. Completely different head pisition even if your stock is in the same place. The opposite is true as well, for a defensive rifle, I'm not going to adjust eye relief from the prone position, probably from the sitting position. Logic? If I was a victim of a home invasion….(with my luck) I'd likely be on the toilet at the time 😉
1 inch is 25.4 mm
Crossed threads are Tite threads and don't require loctite…Pro tip!
I wish my eyesight was good enough to do it with just my eye. Unfortunately, I have to use a laser to do the rough sight in.
I saw an earlier comment on this same point: when you were tightening the mount to your gun, you should have had the rifle pointing down. That way the mount would be pushed forward against the rail, reducing the effect recoil will have on your zero.
Once i got my first ar i was on this channel like flys on stink i got an m&p sport 2 with the law enforcement free float handguard and i threw a vortex spitfire 3x gen2, a kung fu grip, magpul dust cover and angled grip, aero 45 degree angle safety and forward assist, bcm butt stock and charging handle, geisseles takedown pins and bolt catch, and last but not least an armaspec stealth recoil spring and caleb and brownells is who i go to every time to figure it out 😎😎😎
Just ordered one.
Thanks for the information.
Oh my GOSH!!! Caleb is STEALING my content!!!! He's using the same scope and screwdriver I used….and he's wearing the same Dixon shirt I did. How rude!!!! 😂
In here before someone else claims they have already filmed this and that Caleb and Brownelle’s is copying them.
Is your vise level?lol
That scope level is a neat piece.
Hi Caleb from Brownells here
Lot of people worry about scope placement. It doesnt inherently matter how far back or forward you do it. I have my optic hanging about 1" rear of the receiver with the mount in the rear most pic section
Does Brownells sell the Arisaka tool? Can you give us a link?
at 64 and x armor crewman I mount the same way come back a day later and check my work
Caleb, I noticed, from what I've seen and heard others state, a discrepancy when you mounted your optic mount to rail. They've always recommended you push the mount forward, in rail slots, before tightening the mount. This allegedly helps prevent recoil mount movement when gun is fired. As far as I can see; your method does the opposite.
Also, if your going to level the scope using the scope mount instead of using the turret; what is the point in having the scope mounted while attempt to do this… ? Why not just level the scope mount before installing the scope ? Unless I'm missing something; seems like it would be a lot easier.
what bipod is that?
I might have to pick up one of those leveling tools. I’ve been using a picatinny mounted level in combination with another level on the turret. Then I verify the crosshairs are level with a known level surface like a window frame or something
I always level my rifle and then level the scope off the turret cap. After I torque everything down I double check that the reticle is level with a plumb bob. I haven’t had an issue yet after mounting dozen of my own scopes.
Knowing and understanding the offset is important. Some mounts will preclude the use of backup irons; won't be able to get correct eye relief and have the rear irons mounted
I don't understand having the scope completely overhang the rear backup sight. You would then have to remove the scope in order to use it. I guess if you have a quick detach cantilever scop mount, it's easy enough to do, but don't most LPVOs (maybe all) have a reticle of some sort etched into the scope? So even if the illumination fails because of batteries or whatever, you still have an aiming reticle that works.
That method doesn’t always work. Had a Leupold mount when you tightened it up, it was off with the receiver.
I’ve mounted scopes but I’ll still listen to Caleb.
Great thank you for the video.
✔️✔️💯📈 nice
Just got my first LPVO and here comes Caleb! Thank you sir.
Now wheres that Arisaka thingy at? LOL
if you're putting a scope on an AR, you need to re-think your life