Leveling a scope

J

jp1957

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Minuteman
Jul 9, 2025
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Washington
#1
Ok, have read the various ways to level scopes posted here.

The fundamental flaw I see as a machinist, is you need to know the bubble level itself is actually level when mounted or the tool you use is actually level

So I have a granite surface plate, its level within .0005 in 10 inches using a Starrett master level

I bought 2 US Optics scope cant levels (which BTW really suck and wont use them), 1 is fixed, the other swings out.

One was close, the other way off. The scope on my rifle was done by a pretty good gunsmith I'm told. He told me to level by the top turret, and thats making an assumption that point is even level. (and reading here says it may not be)

Using top of turret, its not level either (now I havent done the plumb bob verification yet)

So heres my question, I can lay my machinist level across the top of the rail, and level to that, but then thats making an assumption its level to the rail wedges themselves.

Or do I care if they differ, as long as reticle with a plumb bob aligns? And scope mounted bubble level is zero'd as well

TIA
 
#3
Bkultra said:
Level the scope using the plumb bob, and then match the bubble level to your reticle. Don't worry if the bubble doesn't match level to the rifle etc. You're hardly ever have your rifle perfectly level anyway.
Click to expand...
That's the part that doesn't make sense.

yes the rifle bore and reticle would be level with each other, but if the rifle is already canted when you do that

That's why I was asking about rifle level across the rail first, establish level, them plumb bob reticle
 
#5
Don't level to the top of the scope turret. Level to the bottom bottom of the turret housing. That's what manufacturers level the reticle to. Once done, confirm with a plumb bob. As long as you rifle level (send it, bubble level etc) is level to the reticle (and the reticle track true) you should be good to go.
 
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#12
My money is on the OP’s inability to outshoot whatever teeny, tiny differences may exist from using these various methods lol. No offense OP, but as others have noted, use a plumb bob to level the reticle, match the rifle level to the reticle, and run it. If you’ve purchased quality gear and ammo, and everything’s torqued to spec, it’ll be close enough to get the job done way out there (quite likely better than you can do). Don’t lose sleep over it. :)
 
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#14
Fact: Approximately 25% of students who pay $1,200 for 3-days of precision rifle training show up with a scope that is not plumb to gravity in the rings / mount. We correct this early on Day One to limit mechanical error before hammer forging shooter fundamentals to limit shooter influence. Plumb rights the vertical plane. Level rights the horizontal plane. Focus on plumb and level will follow.

-- Taylor
 
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#15
I level the rail on the rifle with it in a vice....and yes, this assumes that the level used is reasonably accurate. I then put a Wheeler level on the barrel and adjust until it shows level...now I can move the rifle and still know rifle level.

Then I level the scope in the rings....if I have enough room below the erector housing to use Arisaka leveling kit...this:

210932.jpg


Just because I'm a belt and suspenders kind of guy, I've leveled the scope via the erector housing bottom with a level on the top of the turret and found a number of levels that match.

As a machinist, you probably have feeler gauges or similar which can be used but I'm just a home hobbyist the Arisaka kit works for me.

Then confirm with flashlight and plumb bob in my home.

Then I forget about all that crap and don't worry about any very small errors that may still be present.

And as alluded to by a poster above, canting the rifle/scope combo introduces much more error down range than the reticle just being a few degrees off. Its posted somewhere here...oops, I found it. See attached.

Different people have different ways to skin this particular cat...this is mine.
 

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  • Reticle vs Rifle Cant Analysis.pdf
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#16
jp1957 said:
That's the part that doesn't make sense.

yes the rifle bore and reticle would be level with each other, but if the rifle is already canted when you do that

That's why I was asking about rifle level across the rail first, establish level, them plumb bob reticle
Click to expand...
Yea, you gotta level the rifle first and have a way to keep it level.
Use the wheeler level kit.
Put the little level on the rail, then attach the level that clamps onto the barrel. Make both levels match
The level clamped on the barrel is a constant reference to make sure your rifle is staying level, while leveling the scope.
Then use whatever method you want to level the scope in the rings (plumb bob, top of turret, bottom of turret, etc), and attach your permanent level o your scope, rail etc.
 
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#18
trob said:
Yea, you gotta level the rifle first and have a way to keep it level.
Use the wheeler level kit.
Put the little level on the rail, then attach the level that clamps onto the barrel. Make both levels match
The level clamped on the barrel is a constant reference to make sure your rifle is staying level, while leveling the scope.
Then use whatever method you want to level the scope in the rings (plumb bob, top of turret, bottom of turret, etc), and attach your permanent level o your scope, rail etc.
Click to expand...

Except those levels are proven to be junk. Which is exactly why I don't buy into that.

He has Starret machinists levels. You don't use wheeler when you have those 🤣
 
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#20
Spartan67 said:
Didnt Lowlight post a trick on leveling a scope by using a deck of playing cards as shims?
Click to expand...
He also used a 32 blade feeler gauge set.

That's what I use. I first level the rifle off the pic rail using a Starret 1-3/4 Inch Base Diameter, 1 Circle, Plastic Bull's Eye Circular Level.

Then I place the scope in the rings and use the feeler gauge to level the scope off the bottom of the turret housing & the top of the Pic rail.

I confirm level using the circular level on top of the elevation knob, and also use a plumb bob to check the reticle, just to make sure.
 
#21
I used a plumb bob to verify that my window center frame part is perfectly vertical in my house. Since that point - I just sight through the scope to get my plumb for every scope mounting job from that point forward.

But I will readily admit that my scope mounting skills exceed my shooting skills - so I will never know if it’s perfect or not.
 
#23
mattc51 said:
I just mount the gun up in a tripod and look through the scope while facing a mirror. Turn the scope body till the reticle falls straight through the center of the muzzle and equally through the turrets and it is good to go.
Click to expand...
This is an interesting method I’ve not thought of before. I’ll have to look into it some more, but it seems to make sense. As I’m understanding it, it doesn’t matter if anything at all is level for the process, you just align the reticle through the bore and the turrets. The whole thing could be canted as far as the tripod allows and it wouldn’t affect it.
 
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#24
Arisaka Leveling tool or Feeler Gagues. The plumb line method is maddening.

Think those 2 lines drawn on the tube, somewhere in China, by the lowest bidder are precise? Guarantee a deck of cards is more accurate than lining up multiple bubble levels against a string.
 
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#26
I clamp my rifle in the vise with the bolt removed. I can sight through the bore at the plumb line I have drawn on the wall of the shop. (looking down the muzzle to the breach) I balance my 4' Sands perpendicular to the bore on the scope pic rail and adjust rifle cant until the bubble is right on the money. I then place the scope on the rail with the rings loose enough to be able to roll the scope. Clamp the rings to the pic rail to torque, check to be sure the plumb line is still visually centered in the bore. Shine a flashlight into the objective lens and out of the ocular. Roll the scope until the vertical cross is parallel to the plumb line. Carefully torque the rings...I generally turn about 1/4 turn in a criss-cross pattern until there is some resistance and then use the torque wrench.

Note that I don't care if the rife is pointed up or down, only that it is level when measured perpendicular to the bore.

If I am using a level to reference while shooting, I adjust that level at this time.

If I am using just rings, I balance the level across the bottom ring half already attached to the rifle.
 
#28
I understand completely where the OP is coming from I too am a toolmaker/machinist for 46 years. My last gig was making linear motion guides, I routinely worked to 7 Microns.
Our brains work different.
As far as scope mounting I shim from the top of the rail to the bottom of the turret, done. The less tooling the less error.
 
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#31
Rocketmandb said:
I prefer a laser level and like to do it indoors where wind can't move the plumb bob. The nice bright red line is really easy to line up with the reticle.
Click to expand...

Wait, I was a builder for 25 years. Are you telling me I can only use a pumb bob outside?

I have a heavy large brass plumb bob on a red line. In a pinch, I’ve tied a rock to a length of green paracord at the range.
 
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#32
Im2bent said:
So I see a bunch of posts saying level the rifle, but I have seen posts saying plumb the scope with rifle held at your natural cant.
Click to expand...
If you have a natural cant. Shooting off hand and across your body...sure, lots of cant if you fit the butt pad into your shoulder pocket.

But prone, bench, really any rested position and I want that butt pad as close to my neck as possible (so I don't have to roll my head) and I have never seen where there is a cause of cant from such positions. But....maybe others do.
 
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#36
I used to level the scope off the top turret or bottom face between the scope base and it seemed to work ok for what I was doing, until I got into PRS. At a match a couple years ago, I realized I needed to consistently hold more wind than the other shooters in my squad. I was fortunate to be shooting in a squad with some pro level shooters and after talking to them and studying things for awhile, I realized that my old method wasn't cutting it. After that match, I checked the scope reticle compared to a plumb bob and confirmed it was slightly off. I also shot a tall target test and confirmed it was off. It wasn't much, but it didn't need to be to cause issues like I was seeing at that match. Ever since then, I've been using the plumb bob method and it's been fantastic. Confirmed it was fixed with a tall target test. I am now a firm believer in using a plumb bob to make sure the reticle is plumb to gravity. You're making a big assumption that any machined surface on a scope is perpendicular to the travel of the reticle. Lesson learned for me.
 
#38
OP, you can use something like the Badger Dead Level to plumb the reticle and then mount it to the rifle. I believe that’s what Frank and Mark do in their classes.

I use the EXD tool to level the rifle+scope combo, and then use the edge of my neighbor’s house. More here:
www.snipershide.com

Leveling a scope is dumb

Everyone is built differently. I always have a natural cant, so I do it my way. It works. My point is that leveling the scope when the rifle isn't in its natural position is not the end. You brought up shooting offhand, not me. I was merely responding to that. Sorry, that ruffled your...
www.snipershide.com www.snipershide.com
 
#40
Lowlight said:
Drop a plumb line for free ...

spending money on this stuff is silly
View attachment 8759914
Click to expand...

Which one of the four is correct ?? either way 3 are wrong
exactly who is calibrating the ones you buy ?? the OP has a machinist level the only one posted so far that is truly accurate. I look at some of these "levels" and laugh I wouldn't trust them to be within a few degrees.
 
#41
I just mount the gun up in a tripod and look through the scope while facing a mirror. Turn the scope body till the reticle falls straight through the center of the muzzle and equally through the turrets and it is good to go.
Click to expand...
Pretty neat idea, if I can just stand looking at the ugly man pointing a gun at me:ROFLMAO:
 
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#42
Learned it from the Air Rifle crowd. Still have to do some test shots. I have come across some where the scope is not parrallel to the barrel and so close up shots (10 yds) hit to the side of point of aim, zero distance (25 yds) hits point of aim, and behind zero distance (50yds) hits to the opposite side of point of aim. Then it comes down to getting the mount and barrel in the same parrallel plane.
 
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