Bubble Levels Suck

[mobo215]

My father is a carpenter, and has several 4'-6' levels that were VERY expensive. So I did a test to check them on a known flat surface (his tablesaw outfeed table, the flattest surface on Earth and meticulously leveled to perfection):

1. Lay the level on a flat surface and trace it.
2. Rotate the level 180 degrees, so the left side is where the right side was in the traced lines (and vice-versa)
3. See if the bubble lands in exactly the same spot. If yes, the bottom side of the level is true and flat, and the bubble glass is set perfectly parallel to this plane.

His 6' level checked out PERFECTLY in multiple spots on the table, and at every angle (across the table, lengthwise along the table, diagonally across the table, etc.). His 4' level also checked out perfectly. Both tests confirmed that the table was level in every direction and as perfectly flat as humanly possible.

I then proceeded to check several of my 6"-9" pocket levels on this same flat surface. I had four on hand to check. One of them was a fancy machined aluminum level that cost over $40 back in the late 90s, and it actually was the worst of the bunch. Without a single exception, I could detect that the bubble did not "return to zero" when I did this same test. It was obvious to my naked eye that the bubble was not set perfectly parallel to the straight edge on the bottom of the level.

So why would anyone trust those cheap little levels to mount a scope? The margin of error increases exponentially with shorter level bases, and combined with the short transverse surface of rail, it compounds both errors to the point that your naked eye could do a better job of leveling the scope.

Wouldn't it be better to mount the rifle into a bench vice with the bolt removed and compare the center line of the bore to the crosshairs against a known plumb object such as a plumb-bob hung from a tree branch at distance (the further the distance, the less error), or the corner of a building? This would provide a plumb reference for the crosshairs, and it would also control for any parallel "offset" between the bore centerline and crosshair centerline.

I would buy one of those wedges that make the bottom of the scope perfectly parallel with the rail, but I have a 1-piece rail with medium height rings which don't provide enough room to use it. And I don't trust that the surfaces are truly parallel, especially across such a short bearing surface.

Anyway, these are my autistic thoughts for today. I'm a new shooter, so don't hesitate to tell me why I may be wrong!

 

[M4orturnate]

It's more about shot to shot consistency then being perfectly level. I check my bubble level against my send it against a plumb bob at 30y and they all check out.

 

[hlee]

Having a scope mounted level to the rifle is only important if you hold the rifle level. Most people do not. This is why there are adjustable butt plates. As an exercise, mount a scope level to the gun. Then, shoulder the rifle with your eyes closed. Open your eyes. Even money says the reticle is not level.

TLDR- Mount the scope such that it is level to the fall of gravity when the rifle is being shot, not when the rifle is sitting on a bench.

 

[oldrifleman]

Yeah I have a bubble on my mount but I switched to a sendit as I pay more attention to it. I checked and they agreed. I agree though that it is about doing the same thing each and every shot.

 

[mobo215]

What’s a Sendit?

 

[M4orturnate]

What’s a Sendit?

Electronic level. Much faster and in your face then a bubble level

 

[mobo215]

Having a scope mounted level to the rifle is only important if you hold the rifle level. Most people do not. This is why there are adjustable butt plates. As an exercise, mount a scope level to the gun. Then, shoulder the rifle with your eyes closed. Open your eyes. Even money says the reticle is not level.

TLDR- Mount the scope such that it is level to the fall of gravity when the rifle is being shot, not when the rifle is sitting on a bench.

Agreed and understood, but when I say "level" what I really mean is that the vertical crosshair is perfectly in line with the centerline of the bore, assuming that the center of the crosshair is perfectly centered in the scope when the windage knob is set exactly to the mid-travel position. No matter how you slice it, if you shoot the rifle canted (even if the crosshair is perfectly aligned with the bore) you'll wind up with some combination of windage and elevation when you adjust either. And it seems that this error is magnified with larger scope offset heights (correct?).

I haven't shot beyond 350yds yet because I live in Philly and it's a long drive to anywhere with longer ranges. None of this really matters much at that range in my limited experience. But I want to work my way up to maybe 1000yds, which is entirely possible within a 4hr drive from here, and that's right about where this stuff seems to matter.

 

[cas6969]

You trust the bubble to be right for the same reason you trust the electronic one to be right I guess.

(because in reality you have no idea if either of them are right)

 

[oldrifleman]

Ok, the issue is you are beginning to understand the term tolerance stack up. There are inherent issues all along the path. Your interface with the action mounting bolts, the mating of the barrel to the action the rail to the action, the scope mount to the rail and the scope to the rings. Each place is an issue. That is why we practice doing everything the same each time. We get all of the interfaces as close as possible and then learn how the rifle reacts and create the DOPE card based on the rifle as it sits.

 

[Huskydriver]

Who uses a level to mount a scope thats fudd bullshit

 

[Baron23]

Somewhere here is a post…maybe posted by @Lowlight but I’m not sure if he did the math or just posted it info up…the upshot of which is have the rifle canted is far more of an impact than the scope level to the rifle being off a small amount.

And the point about adjustable but pads is well taken for shooting off hand and NRA HP type positions. I don’t do either and I’m personally fine with my gun being actually level.

Now I’m only slightly OCD (actually just a bit of a perfectionist..real OCD is and awful condition). So yeah, I really do want all of the above to be spot on.

So, I level the rifke with a Send-it on the scope rail(or use a bubble level you choose to trust). Then level the scope to a plumb bob.

If you use a bubble level that won’t fit under your scope when it’s put in the rings (most likely I think) then before mounting the scope and with the rail level, you can then use a Wheeler level kit to put their adjustable level on the barrel so when you take the bubble level of the rail you still a reference to gun level to use when leveling the scope to the plumb bob.

Does this get me any more accuracy? Highly doubtful …but it makes me happy and I’m retired and have time to fuck w crap line this. lol

 

[hlee]

Agreed and understood, but when I say "level" what I really mean is that the vertical crosshair is perfectly in line with the centerline of the bore, assuming that the center of the crosshair is perfectly centered in the scope when the windage knob is set exactly to the mid-travel position. No matter how you slice it, if you shoot the rifle canted (even if the crosshair is perfectly aligned with the bore) you'll wind up with some combination of windage and elevation when you adjust either. And it seems that this error is magnified with larger scope offset heights (correct?).

I haven't shot beyond 350yds yet because I live in Philly and it's a long drive to anywhere with longer ranges. None of this really matters much at that range in my limited experience. But I want to work my way up to maybe 1000yds, which is entirely possible within a 4hr drive from here, and that's right about where this stuff seems to matter.

Ok, let’s put this differently. Let’s imagine that your scope is 5 degrees off of level from the rifle’s “true level” (such that you cant the rifle toward your body to make the reticle level) and sits 3 inches above the bore. The reticle center would sit 0.25” (laterally) away from the center of the rifle bore. If you were to then zero the rifle at 100 yards, you would expect your average impacts at 1000 yards to be off by 2.5”. That is well within the error of the myriad of other factors that affect bullet flight.

Five degrees is a huge amount. The average human is likely to easily identify and correct a 1 degree error. Leveling the scope to the rifle is overblown and largely irrelevant- within reasonable bounds.

 

[Yondering]

Seems like people are talking about 2 different things here - mounting a scope to be level, as the OP said, and shooting with the rifle level. Different topics.

In regards to mounting a scope level, OP your dad probably could have explained this too; it’s the difference between just owning tools, and knowing your tools and how to use them. A bubble level doesn’t have to be perfect*, it just has to be used consistently.

For example, use the level to mount the rifle in a vise so the level reads zero on the scope base, action, or whatever your reference is. Note the orientation of the level, and mark it if you need to.

Then put the scope in the rings and if you’re leveling to the top cap, put the level on in the same orientation. This way it doesn’t matter if the bubble wasn’t perfectly true to a water surface, you’ve aligned the scope and action to the same amount of error in the same direction, so they’re true to each other. The level doesn’t have to read the same in both directions, it just has to be used in the same orientation on both parts to make them aligned.

(*especially for carpentry tools, which are generally much cruder than machinist tools regardless of the cost)

There is also likely some error between your scope’s top turret cap and the reticle, but that’s a different topic than how to use a bubble level.

 

[Sheldon N]

Agreed and understood, but when I say "level" what I really mean is that the vertical crosshair is perfectly in line with the centerline of the bore, assuming that the center of the crosshair is perfectly centered in the scope when the windage knob is set exactly to the mid-travel position. No matter how you slice it, if you shoot the rifle canted (even if the crosshair is perfectly aligned with the bore) you'll wind up with some combination of windage and elevation when you adjust either. And it seems that this error is magnified with larger scope offset heights (correct?).

Scope centered directly over the rifle bore doesn't really matter, the theoretical horizontal offset is very small and gets lost in the noise.

Scope reticle/erector level to gravity at the moment when you shoot matters a lot.

 

[Rob01]

Agreed and understood, but when I say "level" what I really mean is that the vertical crosshair is perfectly in line with the centerline of the bore, assuming that the center of the crosshair is perfectly centered in the scope when the windage knob is set exactly to the mid-travel position. No matter how you slice it, if you shoot the rifle canted (even if the crosshair is perfectly aligned with the bore) you'll wind up with some combination of windage and elevation when you adjust either. And it seems that this error is magnified with larger scope offset heights (correct?).

I haven't shot beyond 350yds yet because I live in Philly and it's a long drive to anywhere with longer ranges. None of this really matters much at that range in my limited experience. But I want to work my way up to maybe 1000yds, which is entirely possible within a 4hr drive from here, and that's right about where this stuff seems to matter.

Yup you can level the scope when mounting but then you want the scope level when shooting so that is where a bubble level comes in as a helpful reference point. I used an electronic level almost 20 years ago but never warmed up to it and like the scope mounted bubble better for quick reference point.

Mifflin is less than 3 hours for you and closer than Peacemeker.

 

[ma smith]

levels really come in handy when you have no fucking clue what level really is...

 

[Sullypants1]

Can you do me a favor? a little experiment.

Take the long 6' and 4' levels that zero out both ways, place them on the table, level.

Then repeat the same tests with the small bubble levels but you place them on top of the machined top of the long levels.

I'm just curious.

 

[mobo215]

Can you do me a favor? a little experiment.

Take the long 6' and 4' levels that zero out both ways, place them on the table, level.

Then repeat the same tests with the small bubble levels but you place them on top of the machined top of the long levels.

I'm just curious.

Been there, done that. The problem is the alignment of the capsules relative to the straight edge surface of the level body. Cheap pocket levels are almost always the suck.

 

[Yondering]

Been there, done that. The problem is the alignment of the capsules relative to the straight edge surface of the level body. Cheap pocket levels are almost always the suck.

For scope mounting it doesn't really matter though, if you stop and think about how to use the level correctly (i.e. the same level in the same orientation for all measurements). Where people mostly go wrong with these are those dumb kits that use two different cheap bubble levels, one mounted to the action rail and one on a scope turret - that sort of setup sounds good if you don't think about it, but can (and usually does) have all sorts of error.

For shooting, that's why you adjust the scope mounted level to read zero in the same setup where you just leveled the action and then the scope together. You'll likely still have a small amount of error in that system, but it'll usually be smaller than you might think, and it's easy enough to verify by holding the scope reticle in alignment with a plumb line and checking the bubble level.

I think a lot of people poke around with bubble levels and see the error in them, but don't really have a very good perspective on how much error they're seeing and how much it matters (or doesn't). I've heard all sorts of wild claims about the innacuracy of bubble levels, with people saying you can't detect an angle change smaller than 3°, or 5°, or even 10-15° from one bozo. In my own experiments, comparing various different bubble levels to an expensive digital level at work, I've been able to detect angles as small as 0.3° with most bubbles, and even 0.1° with good long-vial bubble levels. That means when holding a rifle level with the bubble "zeroed", you can be within 0.3° with pretty good confidence - that's a very small angle, much smaller than a lot of internet claims about bubble level inaccuracy. This is easy enough to verify on your own too; don't just take my word for it.

 

[Gunfighter14e2]

To me they are nothing but added useless weight, and a distraction. Long ago on the @j-huskey short range I shot a 1/2moa group at 600, then I tilted the rifle to both the right & left as far as the Harris pod would allow and shot 3 shot groups. Both groups were 1/2moa right & left of the base group. The mechanical off set of the 17X USO was 2.05". Your eye should find the scope plum line on any target w/o issue.

 

[ToddM]

As others have mentioned there's really two things going on here, both very important and often overlooked. 1) You need the rifle either level, or canted as you shoot it. 2) You need the reticle/erector travel aligned with a plum bob when #1 is maintained.

I'm of the camp that if you set the rifle level (or canted how you shoot it), and then level the scope at the range with a plum bob and verify it with erector travel you are doing better than 99.99% of folks. Levels that clamp to scopes or rails all drift depending on how much you tighten the clamp. The scope tube levels all end up getting bumped out of alignment. Most scope manufacturers allow for +/- 1 degree offset between the reticle and scope body so you can't trust that either. Which is why I've never liked the leveling setups that use the bottom of the scope body with feeler gauges or a wedge except as a starting point.

The biggest problem usually always boils down to 1 thing, a fundamental inability to indicate level (or desired cant) on the gun and maintain it through the whole process. That includes range testing once the optic is mounted.

The problems I find are usually 3 areas.

1) Many rifles have no flat large enough to get a good level on, and if it does, you almost always lose that surface when you mount the optic, and almost none of these gun vices hold tight enough to ensure a gun does not drift level while working. Especially if you get a scope mount that's "sticky" and requires more force to rotate the scope during adjustment (I'm looking at you Seekins and Warne).

2) You can buy 10 different gun/rail levels etc. and put them on a nice calibrated machined long level and if you are lucky 1 will agree with it. So you need levels that have adjustable zero.

3) Tolerance stacking, I've seen rifles where the flat on the action does not agree with the flat of the installed scope rail, and neither of those agree with the flat on installed scope ring caps. Built in levels in scope mounts, scope rails, stocks are usually the worst because the vials are super tiny.

If I had the ability to design/sell a scope level kit this is what it would include.

• A nice 4-6" level with a long bubble, or calibrated (or zero reset) digital version, angle cube etc. That way you can start with the action (if you have a flat) nicely leveled or canted how you shoot it.
• A barrel clamp level that's adjustable after it's installed so clamping force does not impact the level adjustment
• A digital picatinny mount level that you can set zero on and it remembers it.
• Simple plum bob and tall target test

My process would look like this:

1) Set the action level (or canted how you shoot) in a gun vice using the flat on the action.
2) Install adjustable barrel clamp level and adjust it to agree with the action level.
3) Install rail, rings, optic (pay no attention to the level on the top of the rail, rings, scope body)
4) Install picatinny rail digital level and zero it to agree with the barrel level. It is now set to be level to the action flat. If you can't zero it, it's worthless.
5) Proceed to range, you can now reference the digital picatinny level that in theory should be leveled to the action flat while leveling the reticle to a plum bob and/or tall target testing and you can also now use it as your reference during shooting.

Overly complex, almost certainly, but it's the only method I've seen that ensures you maintain level of the action (or desired cant) from start to finish of the process.

 

[Shifty6BR]

 

[FredHammer]

Having a scope mounted level to the rifle is only important if you hold the rifle level. Most people do not. This is why there are adjustable butt plates. As an exercise, mount a scope level to the gun. Then, shoulder the rifle with your eyes closed. Open your eyes. Even money says the reticle is not level.

TLDR- Mount the scope such that it is level to the fall of gravity when the rifle is being shot, not when the rifle is sitting on a bench.

100% agree.
If I am able to cant the butt pad, I will level the gun with a bubble and level the horizontal crosshair on a horizon/field line/50yd long machine shed at 2100yds.
If I don't have the option of butt pad cant, I shoulder the rifle how I naturally do, and just keep the horizontal crosshair on a horizon object.

 

[Evolution 9]

Mobo,

As previously stated, getting the scope level to the gun is nice but not actually important. I put effort into it because I’m a perfectionist but it isn’t actually important unless you’re getting things comically (intentionally) unlevel.

Getting the crosshairs level to gravity is pretty important, but you’re missing something about many of the bubble levels that are used for shooting.

They are fine tune adjustable!

Yes, many hardware store levels are inaccurate. You correctly identified one way to test them. But a scope mounted bubble level is mounted to a round tube so it’s exactly as accurate as you’re willing to make it!

Just fine tune it’s position on the scope until it’s dead center while the reticle is plumb with a plumb line in front of it. Simple, and very precise.

Contrary to some very stupid statements that have been made in past threads on here, most people are able to discern very slight variations in the centering of the bubble in a level, which, in most bubble levels, translates into very precise adjustments.

You’ll see some on the Hide talk about the variation possible while the bubble is “between the lines” being several degrees. This is an asinine statement. It may be true, but only an epic fudd considers that they’ve made an attempt at leveling simply because the bubble is somewhere within that wide space.

Mount your scope with a bit of care. Mount your scope mounted level with lots of care. Shoot. Enjoy.

 

[mobo215]

el.

Getting the crosshairs level to gravity is pretty important, but you’re missing something about many of the bubble levels that are used for shooting.

They are fine tune adjustable!

Yes, many hardware store levels are inaccurate. You correctly identified one way to test them. But a scope mounted bubble level is mounted to a round tube so it’s exactly as accurate as you’re willing to make it!

Just fine tune it’s position on the scope until it’s dead center while the reticle is plumb with a plumb line in front of it. Simple, and very precise.

But doesn't it matter also that the rifle's bore axis is in line with the vertical line of the crosshairs? I would think that this is what needs to be aligned, not some flat surface on the rifle which may not be perfectly parrallel or perpendicular to this. And what effect does a 20moa scope base add to the equation?

I guess I'm splitting hairs here needlessly for the ranges I'm likely to use my rifle/scope for. Honestly, I simply eyeballed the three turret caps and tightened the rings to 18 in-lb. If you really think about it, you're only "eyeballing" when centering a bubble in a level anyway. The vertical crosshair checks out against a plumb surface at distance, and it also aligns with the center of the bore (I took the bolt out and boresighted to compare the relationship between bore centerline and crosshair centerline.)

 

[Evolution 9]

You are correct that all these things matter… but they matter less than you seem to think. You’d have to be pretty noticeably off in your scope/bore offset to even get 1/8” of offset. This would result in 1/8” difference in point of impact at 200 yards (assuming a 100 yard zero).

Nobody in existence shoots well enough to notice 1/8” at 200 yards (benchrest scores prove this).

Get out and shoot. You’ll soon see why most of us aren’t taking this super seriously.

 

[ma smith]

the variation possible while the bubble is “between the lines” being several degrees. This is an asinine statement.

+1. Many people in this thread have no idea what they are talking about.

The slope shall be approved by the building official, but shall be not less than one unit vertical in 50 units horizontal (2-percent slope).

Contractors need to measure 2˚ slopes, and tell the difference between 'level' (windows) and 2˚ slope...ie intentinal slope 'graded to drain' (eg driveway, shower floor).

It follows that any "decent" construction level you buy at home depot will 99% of the time work at this level of accuracy, and if it doesn't will be replaced under warranty as defective. Even small, cheap levels like $10, 4 inch T-squares are pretty damn accurate at this.

Contractors need windows level, and driveways and showers graded...to meet code...ie they are legally responsible / on the hook. It makes sense that the basic tools they use work to this level of accuracy/precision etc.

In general, within 2˚ (±1˚) for rifle shooting is fine, especially inside like 600yd.

The kind of problem where level really matters is more from dis-orientation...

ie, lets say you are shooting a target in front of a berm graded 3˚ for drainage and you are treating the berm as 'level' with your crosshairs...this is 3˚ errors is possibly a problem at 900 yards...

IMHO there is zero chance the level on your scope is centered with 3˚ cant ....
so a quick glance will tell you the horizon you are referencing is 'false level'...

etc.

 

[Taylorbok]

The scope does not need to be level to the action. (read as the error is lost in the noise)
The reticle needs to be plumb to gravity when you pull the trigger. If the reticle is canted you induce the elevation and windage error.

I've got the diagram some where with the math but 5 deg of rifle cant under a plumb scope is something like 1" of windage at 1000 yards

 

[ToddM]

There's actually another factor to bubble levels that you don't hear talked about much outside of machining. Most bubble levels are similar design, 1 or more lines on other side of the bubble and you center the bubble for level.

However, esp. among shooting/scope levels there can be a wide variation on how "touchy" the bubble/lines are. In other words some bubble levels touching a line on either side might be anywhere from 0.2-2 or more degrees out of level.

For giggles I've tested this, using a 6' digital level and putting on various levels I had around the house to see how much "out of level" touching a line meant. Both on small pocket levels, circular levels, rail levels, angle cubes, scope mount/ring levels, and scope tube levels.

The variation was pretty extreme, most all of the actual construction/carpentry, etc. levels were touching a line by the time you were 0.2 deg off center, even cheaper 8" pocket levels, angle cubes easily notice less than 0.1deg. However once I got into scope mounting, scope mount, scope clamp, rail clamp levels things changed drastically. The best took 0.5 deg to hit a line, and the worst was almost 2 degrees. I also noticed that on shooting levels they were not always consistent in how much angle it took to hit the left vs right line. Some of them might hit the line in 0.8 deg one way, but take 1.2 deg the other. Carpenter/Construction levels all seemed to be the same at least in as close as I could eyeball. I can only assume this is due to glass vial variation, or perhaps the axis of the vial not being square in the mount.

Now of course you can easily see by eye that the bubble is not centered before it hits a line, and some lines are tighter to the bubble than others, so the "real" accuracy you can eyeball is much better than what it takes to hit a line but it's a wide variation. You also probably don't want to be "chasing" a super touchy bubble level while shooting, which I'd imagine is why often you also see what appears to be thicker viscosity fluid in some shooting levels it seems.

 

[mobo215]

I've got the diagram some where with the math but 5 deg of rifle cant under a plumb scope is something like 1" of windage at 1000 yards

That's more than acceptable for me. I'm still missing from time to time by a larger margin than that at 400yds and it isn't the scope's fault.

 

[hlee]

+1. Many people in this thread have no idea what they are talking about.



Contractors need to measure 2˚ slopes, and tell the difference between 'level' (windows) and 2˚ slope...ie intentinal slope 'graded to drain' (eg driveway, shower floor).

It follows that any "decent" construction level you buy at home depot will 99% of the time work at this level of accuracy, and if it doesn't will be replaced under warranty as defective. Even small, cheap levels like $10, 4 inch T-squares are pretty damn accurate at this.

Contractors need windows level, and driveways and showers graded...to meet code...ie they are legally responsible / on the hook. It makes sense that the basic tools they use work to this level of accuracy/precision etc.

In general, within 2˚ (±1˚) for rifle shooting is fine, especially inside like 600yd.

The kind of problem where level really matters is more from dis-orientation...

ie, lets say you are shooting a target in front of a berm graded 3˚ for drainage and you are treating the berm as 'level' with your crosshairs...this is 3˚ errors is possibly a problem at 900 yards...

IMHO there is zero chance the level on your scope is centered with 3˚ cant ....
so a quick glance will tell you the horizon you are referencing is 'false level'...

etc.

Very small correction. One unit vertical in 1 unit horizontal is a 100% slope, and the angle of that slope is 45 deg. A 2% slope is 0.9 deg…

 

[ma smith]

Very small correction. One unit vertical in 1 unit horizontal is a 100% slope, and the angle of that slope is 45 deg. A 2% slope is 0.9 deg…

Thank you, this is a good point.

 

[hlee]

The scope does not need to be level to the action. (read as the error is lost in the noise)
The reticle needs to be plumb to gravity when you pull the trigger. If the reticle is canted you induce the elevation and windage error.

I've got the diagram some where with the math but 5 deg of rifle cant under a plumb scope is something like 1" of windage at 1000 yards

A 5 deg cant of a scope mounted 3” from the bore will be offset laterally by 0.26”. If zeroed at 100 yards, the rifle will be off by 0.26” laterally at 200 yards, and an additional 0.26” for each 100 yards thereafter. At 1000 yards, your impacts will impacts will be off by 2.34,” on average.

 

[Taylorbok]

A 5 deg cant of a scope mounted 3” from the bore will be offset laterally by 0.23”. If zeroed at 100 yards, the rifle will be off by 0.23” laterally at 200 yards, and an additional 0.23” for each 100 yards thereafter. At 1000 yards, your impacts will impacts will be off by 2.07,” on average.

View attachment 8458093

I didn't feel like doing the math but ya that looks right. 3" is a hella high scope. I checked my diagram and it was 1.5" HOB which is low but still we get the idea. it'll be lost in the noise of a wind call.

 

[hlee]

I didn't feel like doing the math but ya that looks right. 3" is a hella high scope. I checked my diagram and it was 1.5" HOB which is low but still we get the idea. it'll be lost in the noise of a wind call.

I use 3” because it is “hella high” and with 5deg- which is hella canted- illustrates the point that it’s lost in the noise.

And, 3” is high, but not unreasonably so for a large objective scope mounted over a rifle with an enclosed handguard- like an AR.

I think we’re all mostly on the same page.

 

[stanley_white]

This thread be like…

-Stan

 

[Baron23]

The scope does not need to be level to the action. (read as the error is lost in the noise)
The reticle needs to be plumb to gravity when you pull the trigger. If the reticle is canted you induce the elevation and windage error.

I've got the diagram some where with the math but 5 deg of rifle cant under a plumb scope is something like 1" of windage at 1000 yards

Hi Taylor - are you thinking of this pic or the attached pdf (actually figured out how to embed it in the post also), which I believe Frank originally posted (dunno who generated it originally).

 

[Taylorbok]

@Baron23 not that one in particular, I have a diagram saved similar to what @hlee posted but they all demonstrate the same point.

 

[Dead Eye Dick]

I only know two things about level, if it isn’t it isn’t.

2. my grandfather purchased a wooden carpenter’s level in the 1920’s. in 2016 when we were building our second shop, the damned thing broke. You’d think they would make things to last a bit longer. Only 90 years old. Heck, when I went to the hardware store to get my(his) money back, they refused to pay. Just because the hardware store did not exist when my Grandfather purchased the level, and the store he purchased it from was not only in another state, it was in another part of the country is no excuse, the thing broke and the store should make it right.

More to the point, I am having a heck of a time finding a level that works on one of my rifles. Two levels, one mounted on the chassis, one mounted on the picatinny rail. They disagree with each other. Not a serious issue, except, checking with a decent quality carpenter level (Obviously purchased in 2016) NEITHER are right.

 

[Taylorbok]

I only know two things about level, if it isn’t it isn’t.

2. my grandfather purchased a wooden carpenter’s level in the 1920’s. in 2016 when we were building our second shop, the damned thing broke. You’d think they would make things to last a bit longer. Only 90 years old. Heck, when I went to the hardware store to get my(his) money back, they refused to pay. Just because the hardware store did not exist when my Grandfather purchased the level, and the store he purchased it from was not only in another state, it was in another part of the country is no excuse, the thing broke and the store should make it right.

More to the point, I am having a heck of a time finding a level that works on one of my rifles. Two levels, one mounted on the chassis, one mounted on the picatinny rail. They disagree with each other. Not a serious issue, except, checking with a decent quality carpenter level (Obviously purchased in 2016) NEITHER are right.

It's hard to find levels that agree, just use one and true it to gravity.

If it's on the chassis or rail hold the level so the bubble is where you want it and then true the reticle to gravity using a plumb bob.

if the level is on the scope tube hold the reticle plumb to gravity (plumb bob) and adjust the level to read level.

 

[Dead Eye Dick]

It's hard to find levels that agree, just use one and true it to gravity.

If it's on the chassis or rail hold the level so the bubble is where you want it and then true the reticle to gravity using a plumb bob.

if the level is on the scope tube hold the reticle plumb to gravity (plumb bob) and adjust the level to read level.

I have used the chassis levels, a scope mounted levels, a picatinny mounted level all with very limited success. I can’t see the scope mounted levels unless I take my head away from the cheek piece which seems pointless because by the time I get back to the cheek piece and look through the scope, its all different and according to the reticle, not level. With the chassis mounted level, I have to take my eye off the scope and look down, same problems as scope mounted level. The only picatinny level just isn’t right. So, I find myself looking at the horizon through the scope and leveling the reticle to the horizon. Being a sailor and normally the helmsman, looking off to the horizon, is a well practiced skill. And with sailing wind calls are a given. So, I rarely think about the wind, making wind calls are like breathing to me, it’s an automatic.

As suggested I’ll take the problem chassis level and true it to a plumb bob. Sounds like a plan. It’s a very nice backup when it is working. Until such time as I feel I need an electronic level, I’ll soldier on with the chassis levels. When practicing or when time allows, at least they work.

 

[Stone111]

I am a master carpenter and yes I have high end levels, Stabila etc... What most people dont know or understand is that a level is ONLY good for the distance it can ACTUALLY measure. A six foot level only levels the six feet underneath it, a 9" torpedo level is ONLY good for the 9" underneath it, a bubble level is ONLY good for the one inch underneath it so anything that extends past what the levels length is IS NOT being leveled or plumbed... I have watched guys put a nine inch level on a much longer surface then called the surface good when its between the lines... Wrong! Same with guys who put a 4 foot level on a corner stud then say the wall is plumb... Wrong! When plumbing a wall you need a true straight edge the goes from top to bottom plate and then put your six foot level on the straight edge and check it in 2-3 places for an overall estimation. Laser levels like my PLS state that "at a distance its accuracy has a plus or minus fudge factor stated in the directions" because they know at distance accuracy will degrade. Know your levels capability and apply accordingly.

 

[Taylorbok]

I have used the chassis levels, a scope mounted levels, a picatinny mounted level all with very limited success. I can’t see the scope mounted levels unless I take my head away from the cheek piece which seems pointless because by the time I get back to the cheek piece and look through the scope, its all different and according to the reticle, not level. With the chassis mounted level, I have to take my eye off the scope and look down, same problems as scope mounted level. The only picatinny level just isn’t right. So, I find myself looking at the horizon through the scope and leveling the reticle to the horizon. Being a sailor and normally the helmsman, looking off to the horizon, is a well practiced skill. And with sailing wind calls are a given. So, I rarely think about the wind, making wind calls are like breathing to me, it’s an automatic.

As suggested I’ll take the problem chassis level and true it to a plumb bob. Sounds like a plan. It’s a very nice backup when it is working. Until such time as I feel I need an electronic level, I’ll soldier on with the chassis levels. When practicing or when time allows, at least they work.

What do you mean by "according to the reticle not level"
Maybe it's a practice/ time thing. I shoot both eyes open and I can keep my head on the rifle and basically shift my focus without moving my eyes and pick up the level and the images basically overlay. It looks like the bubble level is in the top sector of my sight picture.

 

[Stone111]

Wouldnt marking a piece of paper with a big plus sign or crosshair and putting it out at 100 yards or whatever, then from a level shooting bench when you have a cheekweld turn the scope so that the crosshairs of the scope match the crosshairs on the target that are leveled and then snug the rings work well? Just spitballin here... Just make sure you 3,4,5 your paper target crosshair for a perfect 90 degree crosshair for an accurate starting point and level the target before you walk away...

 

[Taylorbok]

Wouldnt marking a piece of paper with a big plus sign or crosshair and putting it out at 100 yards or whatever, then from a level shooting bench when you have a cheekweld turn the scope so that the crosshairs of the scope match the crosshairs on the target that are leveled and then snug the rings work well? Just spitballin here... Just make sure you 3,4,5 your paper target crosshair for a perfect 90 degree crosshair for an accurate starting point and level the target before you walk away...

Yes that will work also.

 

[Dead Eye Dick]

What do you mean by "according to the reticle not level"
Maybe it's a practice/ time thing. I shoot both eyes open and I can keep my head on the rifle and basically shift my focus without moving my eyes and pick up the level and the images basically overlay. It looks like the bubble level is in the top sector of my sight picture.

Can’t see the level with both eyes open. Don’t know why, but we always shot with both eyes open in IHMSA.

 

[Stone111]

There's actually another factor to bubble levels that you don't hear talked about much outside of machining. Most bubble levels are similar design, 1 or more lines on other side of the bubble and you center the bubble for level.

However, esp. among shooting/scope levels there can be a wide variation on how "touchy" the bubble/lines are. In other words some bubble levels touching a line on either side might be anywhere from 0.2-2 or more degrees out of level.

For giggles I've tested this, using a 6' digital level and putting on various levels I had around the house to see how much "out of level" touching a line meant. Both on small pocket levels, circular levels, rail levels, angle cubes, scope mount/ring levels, and scope tube levels.

The variation was pretty extreme, most all of the actual construction/carpentry, etc. levels were touching a line by the time you were 0.2 deg off center, even cheaper 8" pocket levels, angle cubes easily notice less than 0.1deg. However once I got into scope mounting, scope mount, scope clamp, rail clamp levels things changed drastically. The best took 0.5 deg to hit a line, and the worst was almost 2 degrees. I also noticed that on shooting levels they were not always consistent in how much angle it took to hit the left vs right line. Some of them might hit the line in 0.8 deg one way, but take 1.2 deg the other. Carpenter/Construction levels all seemed to be the same at least in as close as I could eyeball. I can only assume this is due to glass vial variation, or perhaps the axis of the vial not being square in the mount.

Now of course you can easily see by eye that the bubble is not centered before it hits a line, and some lines are tighter to the bubble than others, so the "real" accuracy you can eyeball is much better than what it takes to hit a line but it's a wide variation. You also probably don't want to be "chasing" a super touchy bubble level while shooting, which I'd imagine is why often you also see what appears to be thicker viscosity fluid in some shooting levels it seems.

That is a good point if someone is going for a super accurate position. The distance between the bubble and the line needs to be exactly the same on BOTH sides and is a hard thing to get right by eye. Higher end levels take this into account and their bubble is almost touching the line... Its hundreaths of an inch I beleive...

 

[Sheldon N]

There's actually another factor to bubble levels that you don't hear talked about much outside of machining. Most bubble levels are similar design, 1 or more lines on other side of the bubble and you center the bubble for level.

However, esp. among shooting/scope levels there can be a wide variation on how "touchy" the bubble/lines are. In other words some bubble levels touching a line on either side might be anywhere from 0.2-2 or more degrees out of level.

For giggles I've tested this, using a 6' digital level and putting on various levels I had around the house to see how much "out of level" touching a line meant. Both on small pocket levels, circular levels, rail levels, angle cubes, scope mount/ring levels, and scope tube levels.

The variation was pretty extreme, most all of the actual construction/carpentry, etc. levels were touching a line by the time you were 0.2 deg off center, even cheaper 8" pocket levels, angle cubes easily notice less than 0.1deg. However once I got into scope mounting, scope mount, scope clamp, rail clamp levels things changed drastically. The best took 0.5 deg to hit a line, and the worst was almost 2 degrees. I also noticed that on shooting levels they were not always consistent in how much angle it took to hit the left vs right line. Some of them might hit the line in 0.8 deg one way, but take 1.2 deg the other. Carpenter/Construction levels all seemed to be the same at least in as close as I could eyeball. I can only assume this is due to glass vial variation, or perhaps the axis of the vial not being square in the mount.

Now of course you can easily see by eye that the bubble is not centered before it hits a line, and some lines are tighter to the bubble than others, so the "real" accuracy you can eyeball is much better than what it takes to hit a line but it's a wide variation. You also probably don't want to be "chasing" a super touchy bubble level while shooting, which I'd imagine is why often you also see what appears to be thicker viscosity fluid in some shooting levels it seems.

You’re touching on what I think is the most important aspect of a bubble level… sensitivity. Two aspects, does it respond to small adjustments in rifle angle and does it respond quickly.

Bubble levels that are sensitive and fast are the best IMO, they help you get to an accurate firing position as quickly as possible. I hate slow “syrupy” bubble levels.

Best ones I’ve tried are the big/cheap Vortex bubble levels and the Flatline OPs Halo bubbles.

Once you have a sensitive level, you can true it to a plumb line and it becomes an accurate level.

 

[Taylorbok]

That is a good point if someone is going for a super accurate position. The distance between the bubble and the line needs to be exactly the same on BOTH sides and is a hard thing to get right by eye. Higher end levels take this into account and their bubble is almost touching the line... Its hundreaths of an inch I beleive...

I’ve seen people who set the level so it’s touching one of the lines when the rifle is level. Should help with repeatability