Where to level?!

Mikecr

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Alignment and level are completely different things.
Also, the scope centerline does not 'have to' match action, or barrel, or stock, or rest, or ring, or turret, or raceway centerlines.
What matters -for level -is the scope's elevation,, and all else would be zero'd out.
For example:
If you purposely mounted a scope left of gun centerline by ~1", and set the scope elevation (either crosshair or dial) plumb with the real world (a distant plumb line), then elevation hold-offs or dialing will work just fine. The ~1" offset would taken out by horizontal bias in the scope(zero'd out). This would be horizontally dead nuts only at one distance and is less than preferred, but that is an ALIGNMENT issue, and not a LEVEL issue.
To suggest otherwise is to assume that a scope would be mounted purely in elevation alignment with everything except what matters (shooting that plumb line).

I used to shoot a competition gun setup for 600yds, with 7degs of cant. No problem, because the scope was NOT canted.
The way to set scope elevation plumb, regardless of all else, is to mount a level on the scope and set that level so that you can shoot a plumb line (through ~50moa of dialed vertical for me). The level has to be adjustable.

An example product to do this is the 'ScopLevel', which mounts on the scope itself. https://scopelevel.com/
Once set, you can move that scope from gun to gun & back, never having to reset it.
I used to have a standard scope (one known to be perfect) which was used for testing on probably 7-8 guns. I had a ScopLevel on it, calibrated with 1st use, and never had to mess with level for any gun I mounted that scope on.
 
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Mikecr

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As far as alignment measuring, you might accept that a level is not a very precise instrument from which to take measurements.
I would trust no less that a digital inclinometer myself.
But then, what exactly would I do about each and every error in the build?
Honestly, I don't even care to know about what I can do nothing about.
 

338 dude

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Old fashion way always works. Hang a Plum-bob with a bright string on a calm day. If that alines with your vertical cross hairs and it shows level, itis.

all of the other stuff gets you close and sometimes right on.

Was a field engineer at one time, in my younger years, and had to shoot level lines for all other trades on site, with very expensive equipment. Was prove wrong once or twice by a old mason with 100’ of water-hose.

”Just cant argue with truth”

.
Water levels I have used them in the past as well they’ve been around since the Egyptian‘s
 

ntsqd

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That level doesn't make any sense to me. An adjustable level (an oxy-moron?) that references what? I'll stick with leveling the raceways and referencing them as my starting level point.

I can see how having the scope offset laterally won't make any difference at one particular distance. However, at any other distance you would need to dial in both windage and elevation because the Line of Action (i.e. the line between the bore CL and the scope's CL) is tilted and not co-planar to one of the scope's adjustment axis. So now you're dialing-in windage for both scope offset and for wind. Maybe that's easy enough to do in reality, but it seems to me that it would be a lot less complicated, particularly when in a hurry, if there is no lateral offset in the scope mounts.
Leveling the scope on a shouldered rifle will suffer from the same problem.
 

Mikecr

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[Offset/alignment/square] are different from [cant/skew/tilt/level/plumb].
It will help to understand them as separate.

When you have a bit of offset from scope center/barrel center, what are you going to do about that?
Tilt the gun, right?
When your raceway skew means absolutely nothing to scope and barrel centers,, what do you do about that?
Tilt the gun?
When your stock appreciates square setting in a rest, but it skews your alignments and bedding is past set?
Tilt the gun, the bags, the rest or table?

Start over:
Let's say your gun is built,, you have what you have. You level your rest. You mount a scope, and zero it.
Then you hang a plumb line, which you will shoot top to bottom.
Where on your gun do you introduce level, so that you can shoot the line without asserting tension in the system (for free recoil firing)?
I suggest that it's better at the end of the chain (point of aim) than in the middle (a point of build).

Put a level freely on the scope tube, and forget all about anything under it.
Shoot the line, see skew, turn the scoplevel to put you aiming dead on that skew line.
Next shooting of the plumb line should be right on the money.
You will never have to readjust that level, for that scope, even if you move that scope to another gun.

On point of aim, pick dialing -or- holdover. Crosshairs often have a bit of skew w/resp to dialed elevation.
And always shoot a line. Do not assume POA=POI. Our bullets are not purely released, but thrown at any angle.
It's not just vertical or just horizontal.

You identified which angle is most consistent through load development, and re-zero'd for it.
Or, you could re-shoot a plumb line to account for this (if a change,, new load). But you don't have to unless it's a problem beyond zero, across a wide range of distances.
Like if your barrel/load throws shots at 45degs, and you could shoot every distance out to 1kyd.
Let's say it prints 3" right, and 3" high at 1kyd. This, after having set your scoplevel as plumb. Then it's not a gun/aimpoint skew, it's a load skew. Be careful to identify it as such, and not Coriolis, spin drift, or mirage. You could shoot a plumb line & adjust your scoplevel at 1kyds. Lotta work, but if you're going to keep this scope/system together, it may be worth it. In this case, I would. But I haven't happened to run into that yet.

What I'm getting at here is that this is more dynamic than static.
You should ultimately prove your level.
I hunt GHs in hilly NE PA. There, minding level for each shot is vital to success.
 

Mostly Tailfeathers

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So why can't scope bottoms and rifle tops just get along? With todays manufacturing processes why can't the bottom of the scope tube be a flat surface that is perpendicular to the cross hairs? A slot down the lenght of the tube with a tensioning device would allow for adjusting the eye relief while still keeping the bottom of the scope level with the top of a flat rifle reciever like the Tikka's, ( or a rail adapter for older rifles). This having to play with bubble levels seems primative with modern manufacturing methods. Until then, lots of good info and methods, I struggle with this on every optic mount. MT
 

WiscGunner

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I think too many people stress over theoretic issues that don’t actually pan out in real life.
For those following the tennis racket analogy it is great for the system after the scope is mounted firm to visualize what happens with a canted reticle but does not apply to mounting a scope as the handle (scope) and the string frame (bore) would need to be separate components allowing for the frame to rotate but the handle to remain vertical.

The rifle needs to be held consistently. Period. If that means canted to the shoulder pocket works best for you, great! If you also shoot offhand such as in PRS then a somewhat leveled receiver will work better along with an unbiased cheek riser when switching from right/left shoulder. If you only ever shoot from one shoulder then a somewhat leveled receiver with an cant adjusted but plate to fit the shoulder is the best option.

If a rifle if non-adjustable and leveled at the receiver yet canted ever time it is shouldered causing the shooter to relevel each shot then this is not setup correctly.

Ultimately the reticle (non-adjusting holdovers) and/or the reticle travel are what needs to be adjusted to level. The scope body, the turret cap, the scope base, the scope base screw head, the receiver top, the receiver bore, the receiver rail, the chamber, the barrel OD/ID, the Barrelbore/scopr bore all are irrelevant and will vary in error from rifle to rifle.

Each shooter needs to choose how they will shoot their rifle and level or adjust the rifle for that method....THEN level the scope reticle OR the reticle travel to plum.

Just about any cant misalignment of the barrel bore from the scope bore will have inconsequential results, ESPECIALLY for hunting. Any fans of doing MATH can attest to this.

WORST CASE SCENARIO
Rifle is 90 degrees on its side with scope plum and an exaggerated mounting height of 3 inches. At 0 yards to infinity the bullet will be 3” offset from the point of aim. If this is how your setup is situated simply leave it be or zero your windage at half your total expected distance.

NORMAL SCENARIO
Rifle is rotated 2degrees from scope axis with the same exaggerated 3” scope height. This will be .0666” offset. This is not adjustable in the scope clicks. A well leveled receiver might be within 1* and out of level starts to visually appear around the 3*+ range. Still insignificant. Now consider most people do mot have a 3” scope height and the error is even smaller. Barrel/liad harmonics, heart beat, and frog farts will affect the POI more than this error.

Now for those people that live in theoretical space like an engineer, please consider the quality of the measuring instruments before calculating the stacking tolerances of the components. These people should only use only use $1000 levels as the standard .25cent bubble level installed in most commercial fixtures has insufficient accuracy by itself. Now stack tolerances of error in how this cheap bubble level tube is mounted in the fixture body. Not suitable for the precision many in this discussion are asking for.

Now if .03333” or less per degree is too much error for you system then a double axis 8-way adjustable laser center aligned with the bore would get your bore best aligned with the scope tube bore BEFORE installing lenses that would skew the image when offset from their own center as is necessary to adjust zero.

Moral of the story, don’t over think it and verify your real world results.
 

P7M13

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Alignment and "Leveling" without a level.
Credit to No_Regerts on NWFA for sharing this. When I first read his suggestion, I thought, "NFW!" It works, plain and simple. Before his method, to level scopes, I had all kinds of jigs adapted from old tooling, digital inclinometer, bullseye level, etc, and all but the bullseye level have sat idle since.

Caveat:
  • This scenario presumes your bases are aligned with the bore and if split bases, aligned with each other.
  • If you're mounting new rings (e.g. a new scope, going from Leupold 1" to Leupold 30mm), recommend you use the ring alignment tools like the Wheeler kit. Yeah, I lap my rings, but YMMV. I also lap my AR upper receivers. OCD.
  • The tough part is finding a cradle where you can rotate your rifle and keep the bore sighted on the visual target. Typically this is something where the rifle is resting on a balance point.
Geometry:
If you imagine lines coming out of the bore axis and the scope optics axis, they intersect. An imaginary plane (imagine a flat sheet of cardboard) is formed by the two intersecting lines. You're using this rifle design basis to your benefit.​

Tools Needed:
  1. Cradle
  2. Bright, high visibility string and a weight (plumb bob, a 4oz or greater fishing weight, etc.)
  3. Proper tools to tighten your rings.
  4. Depending on your eyes, muzzle laser bore sighter.
  5. Nice to have: a micro torque wrench.
Method:
  1. Your scope is mounted semi-loosely in the rings (you can move the scope with some applied force).
  2. Make sure your eye box is where you want it. Don't screw up like I have, mounting and leveling to find your eye box is crap.
  3. You have centered your reticle to factory zero, half way in total turret travel for both vertical and windage.
  4. Find a way to cradle your rifle so you can rotate it on the bore axis. This is probably the hardest part. Last time I did this, I used a block of styro, cut into two pieces and a vee-notch out of both sides that barely fit the rifle fore end (the barrel doesn't wobble when you rotate). I wrapped the fore end in flannel and clamped it up in the vise. It worked, some wobble, and was a major PITA.
  5. If you're not using a bore sighter, remove the rifle bolt. If using a bore sighter, make sure, when you rotate the laser in the muzzle, the dot doesn't move at all on a wall at least 20' away.
  6. Hang the string. Ideally indoors. You'd be surprised what a 1/4 knot breeze will do to a string.
  7. With your rifle cradled, rotate it from ~ -45° to +45°, making sure the string is centered in the bore (visual) or the laser spot is always on the string (can be hard to see).
  8. Rotate back until the reticle zero hits the line.
  9. If the vertical cross hair doesn't perfectly align with the string, rotate the scope in its rings to align the vertical with the string. The barrel and scope are now aligned and level.
  10. Tighten: this is where you can screw up all the work you just did. Like tightening the head bolts on an engine, you slowly increment the torque on each screw to balance the force. I have had scopes rotate on me when tightening. Now I will tighten the screw 30°, move to the next screw on the opposite side, etc, until all are at the same torque.
Wisdom from the Cheap Seats:
  • I prefer the horizontal split rings like Leupys. To me, easier to mount, adjust, etc.
  • Torque wrenches are useful if you don't have a sense of torque when you tighten things. The only kind I really trust are the needle type.
  • In shooting, holding the gun level is something you train to do. Learning to "see" level is also something you train your eye to do. Figure out a method.
  • I'm of the opinion, if you adjust your scope to be level for how you hold the rifle, you'll never be more than a good shot under 200, and iffy at best beyond. Doing that is like aiming your golf swing to the left to compensate for your slice.
  • In long range, a cant bubble is very useful, as long as you can use your other eye to see it. It never made any sense to me to lift my cheek off to look at a level. Also remember, parallax is a big problem with bubble levels.
 
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jimbires

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just did this tall target last night . the upper hole is from a scratch awl , I hung the plumb bob from .
 

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nksmfamjp

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There are several methods.

level scope base transferred to a barrel mount level, then leveling the top turret works at home. …..as does the sliding triangle tool (never for me)…

In the field, I find I can do this best using a leveled target set at minimum parallax adjust distance. Just aim the bore centered on the bullseye and the base or horizontal split ~level. The rotate the scope until the vertical axis is aligned with the target vertical axis. The scope should be optically centered before this process.

torque screwdrivers are import. Lots of aluminum in these things. On weaker rings and scopes 10inlbs will hold it. I got to 15 - 18 in lbs on heavier scopes with good rings. You want to torque every fastener multiple times until it is holding torque without screw turning. This is why the torque wrench is critical. Some scope ring combos need 3ish retorques to hold. More than that, and something is bending….add locktite or file 13 the mount.
 

JustMe2

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Feb 18, 2012
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Maybe this will help with understanding alignment (leveling)?
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