I've been using the Weaver Modular Level system, but am interested in alternatives.

I level the rifle then using a flashlight through the objective I line the reticle up on a plumb Bob on the wall.

Interesting method, powermad.

Would it be critical to also have the bore precisely aimed at the vertical plumb bob line whilst adjusting the reticle to match?

Not for leveling.
I use a bipod and rear bags to level it.
Then with the butt close to the wall move it till it's by the line.
Adjust the diopter to get a crisp image.
Line it up and lock it down.

The traditional recommended method was to aim at something like the edge of a building and orient the reticle to that. That old method ignored the fact that the reticle needs to be vertical/level with respect to the bore/receiver of the gun. If the gun is rotated when mounting the scope, then things will be off when shooting. Unfortunately, unless the receiver has a nice flat spot or something like a Picatinny rail to use with a level, it’s sometime difficult or nearly impossible to ensure that the gun isn’t rotated to some degree. On the other hand, in the days before long range precision shooting became a popular activity, slight misalignments really didn’t matter too much.

If the rifle does have a rail, I prefer the Arisaka/Spuhr system that uses a wedge against the bottom surface of the section of the scope that holds the elevation and windage adjustment knobs. Arisaka Defense

The wedge method is very fast and convenient because it doesn’t require any fiddling with the orientation of the rifle or with levels. The method does of course assume that the flat surface the wedge indexes against is precisely oriented with respect to the reticle. A similar method is to use something like a stack of business cards between the scope and rail. I’ve never tried that myself, but it would be important to ensure that the material isn’t soft enough to allow some uneven rotation when the scope is tightened down.

Something to be aware of with a leveling system like the Weaver is that the top of the scope’s elevation adjustment knob isn’t always square with the reticle. I checked four of my carefully-leveled and mounted scopes just now and although the tops of the elevation knobs of the two Leupold scopes were level with respect to the receiver, the caps of the two top tier scopes were off slightly. It wasn’t much, but it was detectable with a bubble level.

And of course regardless of the method used, once a scope is leveled, it should be checked against a plumb line.

I wish I had seen that Ariska tool earlier.
$28.... Sold!
Looks like it will keep the tube from rotating as well when locking it down.

On my Primary Arms scopes the top of turret was not level with the reticle.
But the light through the front and projected on the wall worked out pretty slick.

Clamp rifle into Black & Decker portable bench/vise in my unfinished basement. Level the top of the rifle, using a quality carpenter's torpedo level.

Install mount(s) on rifle. Confirm top of rifle remains level. If design of mount(s) allows, confirm it is level.

Install scope. If top of elevation turret is flat, confirm that scope is level. Then confirm reticle alignment with vertical seam on basement wall -- which I've confirmed is vertical with a plumb bob.

Confirm how rifle shoots at distance.

I've installed new and moved existing scopes for many years with this method -- at least 25-30 times.

I have a few different methods that I use for different situations aside from the one already mentioned (which I do use myself quite often).

If I am really being picky about the scope being perpendicular to the bore, I take a large sheet of construction paper (at least 24” high) out to the 100 yard range and use a carpenter’s level to draw a large crosshair in the center of the paper (after it’s been stapled to the target backer). If the rifle is very accurate, place three rounds in the center of the crosshair. Then apply 12 MOA of elevation and fire three more rounds. Then go back to center and go down 12 more MOA and fire three more rounds. Be careful to overlay the scope crosshairs over the target crosshairs precisely for each shot.

If all three groups are overlaying the vertical line of the crosshair (12” high, center and 12” low), then the scope is aligned to the bore. If it’s off 1˚ or 2˚, then use a 36” straight edge and draw a single line through the center of each group and that tells you what angle the scope is rotated. So if the line is off 2˚ to the right at the top and 2˚ to the left on the bottom, then your scope is rotated 2˚ clockwise and needs to come counterclockwise 2˚ to be in alignment with the bore. Rotate your scope and try again.

For scopes that have Picatinny rail mounts, a lot of scopes have flat bottoms on the turret housings. I stack credit cards or business cards between the top of the Picatinny rail and the bottom of the scope housing. As you stack more shims, credit cards or business cards, you’ll see the cant in the scope base. Rotate until it’s parallel with the cards and shove in more cards until you can’t shove in any more. Lock down the rings and you should be golden.

For M14’s/M1A’s I remove the front sight and attach a timing gauge to the front sight dovetail. I use a precision bubble level placed on top of the gauge to level the receiver in the rest. I place an orange plumb line on a target 50 yards away, then align the scope crosshairs over the plumb line. If the scope is aligned to the bore, the crosshairs will be overlaid on the plumb line and the front sight timing gauge will indicate level (this only works if your barrel is properly timed to the receiver).

Tony.

+1 for the Arisaka.

quote:

Originally posted by powermad:
Looks like it will keep the tube from rotating as well when locking it down.

If the problem manifests itself, it will be obvious, but if the scope rings are tightened down too much with the wedge in place, it can become difficult to remove the wedge. I usually tighten the rings part way until a bit of pressure on the wedge is obvious, remove the wedge, finish tightening the rings, and then check to ensure the scope didn’t rotate with the last tightening by placing the wedge back in to see that it’s still flat against the scope housing. So yes, that is an advantage.

Another advantage to the Arisaka or Spuhr wedge system is that it’s usable anywhere: at the range or on a fly-in hunting trip and realize that the eye relief is not set right or something is loose, it’s still necessary to check the zero, but at least the reticle can be leveled properly without any grief.

This message has been edited. Last edited by: sigfreund,

I've tried way too many different scope leveling tools, including multiple starrret bubble levels, projected laser levels, the Midway system, etc etc. Then usually after mounting the scope that way I'd go to the range and have to relevel it with the Mk 21 eyeball.

The one system that seems to avoid readjustment at the range is the Spuhr wedge system. Of course it rely's on the bottom flat of the scope being wide enough and level with the actual crosshair but as long as this is the case it works better than anything else I've tried. Also of course it depends on the action scope mount holes being square and normal to the centerline of the action, they aren't always.

All in all the Spuhr system is the best I've ever tried the other wedge system would be the 2nd best. Other bubble systems etc are only as accurate as the least square part of the action which often can be pretty bad............dj

Wow, all this is hurting my head. Let me explain what I am thinking, using suggestions you all have contributed.

The gravity-dependent Weaver system has three variables:

1) one spirit level device requires perfectly perpendicular alignment of some flatspot on the barreled action with the bore axis.
2) the other spirit level device requires perfect alignment of some flat spot on the scope with the vertical crosshair reticle.
3) Both of these factors then depend upon the rifle and the scope being perfectly aligned 90 degrees to the center of gravity to make the spirit level judgements valid in aligning scope reticle to bore axis.

What is the basic concept for orientation of the scope's crosshairs to the bore axis?


I postulate that a downward extension of the vertical crosshair must precisely bisect the bore axis, once the scope mount fasteners are tightened to specs.

Therefore, if I could come up with a combination of implements and actions that would align bore axis with the vertical crosshair axis after tightening down the scope mount to specs, my gun room project would be complete.

Testing/verifying the rifle/scope setup on the range would require a spirit level aligning the vertical scope crosshair precisely to the center of gravity in whatever position I and my rifle are in.

Just thought experiment: hang a plumb bob on the wall.

rifle on a cradle, bore sight the plumb bob line if possible, or with a precisely inserted and aligned laser boresight.

rotate the scope in the mounts until the vertical crosshair matches the plumb bob line, and tighten down the fasteners using any wedge system or other that helps.


Then at the range, using a spirit level to verify the crosshairs' perfect relation to the center of gravity, fire test shots on paper.

Gravity then is not a factor in properly mounting the riflescope, but of course, is when actually practically shooting.


Am I thinking this out correctly?

quote:

Originally posted by RichardC:
Wow, all this is hurting my head. Let me explain what I am thinking, using suggestions you all have contributed.

The gravity-dependent Weaver system has three variables:

1) one spirit level device requires perfectly perpendicular alignment of some flatspot on the barreled action with the bore axis.
2) the other spirit level device requires perfect alignment of some flat spot on the scope with the vertical crosshair reticle.
3) Both of these factors then depend upon the rifle and the scope being perfectly aligned 90 degrees to the center of gravity to make the spirit level judgements valid in aligning scope reticle to bore axis.

What is the basic concept for orientation of the scope's crosshairs to the bore axis?


I postulate that a downward extension of the vertical crosshair must precisely bisect the bore axis, once the scope mount fasteners are tightened to specs.

Therefore, if I could come up with a combination of implements and actions that would align bore axis with the vertical crosshair axis after tightening down the scope mount to specs, my gun room project would be complete.

Testing/verifying the rifle/scope setup on the range would require a spirit level aligning the vertical scope crosshair precisely to the center of gravity in whatever position I and my rifle are in.

Just thought experiment: hang a plumb bob on the wall.

rifle on a cradle, bore sight the plumb bob line if possible, or with a precisely inserted and aligned laser boresight.

rotate the scope in the mounts until the vertical crosshair matches the plumb bob line, and tighten down the fasteners using any wedge system or other that helps.


Then at the range, using a spirit level to verify the crosshairs' perfect relation to the center of gravity, fire test shots on paper.

Gravity then is not a factor in properly mounting the riflescope, but of course, is when actually practically shooting.


Am I thinking this out correctly?

Yes, but when you do all that like I did (with 2 Starret bubble levels and a laser bubble level) you'll get out to the range and it will still look crooked as hell and you'll realign it with the Mk 21 eyeball!

Or you can buy the Spuhr mounts, use the wedge and make it to the range happy. But that's just my experience!

If you can ever find a picture of David Tubb's Silhouette Chin Gun it will make you feel a little better about your scope placement. He dominated the sport so much they banned the gun. Just sayin.......

Thanks for the heads up on that Arisaka wedge. I'll pick one of those up to accompany the little levels I already use.

It's partially similar in theory to the way Scalarworks Leap scope mounts now work with a screw that you wedge in to the bottom of the scope, then you mount the base to the rifle.

I level the rifle and then use a plumb bob set at about 50 yards and match the vertical crosshair in the reticle to the plumb bob. I've also seen where a similar method was done where the rifle was leveled and then a horizontal piece of tape was applied to a wall. Turn off the lights and shine a flash light through the back of the scope and line up the horizontal cross hair to the level piece of tape on the wall.

I have always just eyeballed it. Never had a problem back when I did benchrest

I like the arisaka wedge, but it seems to take more hands than I have. SO I use a Starrett adjustable parallel which does exactly the same thing and has a screw to lock it which solves several issues.
They aren't much more in cost.

Those Starrett's look pretty nifty.

I just got back my new Vortex scope that I had to send back for warranty mounted up using the projection method.
The top of turret is level with the reticle on this one.

I use the two bubble level method along with a plumb bob. Pretty simple and gets we where I need to be.

Some thoughts on the general topic of reticle alignment/orientation.

Not having the scope reticle adjusted properly with respect to the bore of a rifle won’t matter if always shooting at one distance or if the sight is rezeroed every time the target distance changes. Some slight misalignment also won’t matter much if the target is a deer’s or elk’s vital zone at a maximum of 300 yards, nor will it matter if the shooter isn’t even capable of accurately judging whether the reticle is level to the pull of gravity when firing a shot (something that’s often difficult in field situations).

The height of the sight over the bore also makes a difference. The effect of any misalignment will be less if one’s scope is a svelte 3-9×40mm with 1 inch maintube that’s mounted as close as possible to the receiver of a model 70 or 700 rather than if it’s a 5-25×56mm with 35mm tube mounted on a Tikka T3x TAC A1 with its full length Picatinny rail on the handguard.

For precision long range shooting when it’s not possible to zero the sight for the target and it must be engaged by dialing or adjusting the point of aim (holding over), then it becomes important.

If the reticle is misaligned with respect to the rifle’s orientation when shooting, the effect is the same as inadvertently canting the rifle, except the cant may not be obvious because the reticle is off. Recognition that rifle cant is an important factor to consider and avoid when engaging small targets at long distances is the reason for the proliferation of bubble or other types of levels that long range shooters attach to their rifles these days to ensure they don’t cant the rifle when shooting.