Spuhr Mount and Tall Test Questions

[AuNEagle]

1. How accurate is the level built into the Spuhr mounts? Yesterday I was using a scope fixture to level the Spuhr mount and then level the scope in the mount using a plumb bob. The fixture base was level in both directions and the picatinny rail on the fixture was level in both directions as was the flat surface between the rings on the base of the Spuhr mount. However, the level at the rear of the Spuhr base did not indicate that it was level.

To level the scope fixture, I used both a circular surface mount style level with a sensitivity of 0.035 in./ft., 10 min./0.1". I could rotate this level on the various surfaces without changing the reading of the level. I also used the "calibrated" level out of a Wheeler Professional Reticle Leveling System with the same results.

2. What is the minimum distance that it is feasible to do a tall test? I understand the standard use of 100 yards as that is also the distance that many/most people zero their rifles/scopes. However, if you are doing the test with the scope in a fixture, are there any problems with doing the test at a shorter distance with an appropriated reduced size test target? Mathematically, I cannot see why it would matter and using a shorter distance would make it easier to use a test target that is more than 10 mils tall. The only real limitation I've though of is just using a distance that is long enough to be able to adjust for parallax with the particular scope being used.

Thanks for your advice.

 

[CoryT]

The level is so-so, at best. I more or less ignore it. Where precision is needed, use a Send-It or one of the accuracy first units.

You can go closer on the test, but precision will suffer somewhat as it will be harder to see the small errors in the system.

 

[charnicus]

I won’t answer the second part as someone will give better advice though with maths I feel like anything is possible…

As far as the level goes, your best bet is to use one level as reference. And roll with it. Too many levels can cause too many problems. One thou here one thou there is likely to cause some disagreement somewhere. Also keep in mind that your scope may have twisted when tightening the ring screws. I’ve been down that road of frustration but will say no more.

 

[b6graham]

You're unlikely to be able to see OR spend time looking at the spuhr level

If you MUST use a level to shoot There are better options. But again a level isn't necessary

A tall test is relative anyways. A mil at 10y is a mil at 100y. Use what space you have in a controlled environment

If you're tall target testing a hope you're using a rig like the badger or whatever frank uses and not just shooting

 

[Rancid Coolaid]

1. My Spurhs have a bias that is mount-specific. That is called based on leveling in multiple other ways to determine the bias. None of them are "that" far off perfect, but all are off by a little.

2. The 100 yard distance is usually easy, the shift in reticle relative to target is easy to spot, and everyone is accustomed to what that shift should be without risking (much of) a math error. You can do a shorter distance, just get the math right. Turret errors aren't usually consistent across the entire rotation, or that has been my experience. If it is a go/no-go exercise, you don't really need to know where the error is, just whether it passes your test or fails it.

Edited to say you can do a tall target on a calibrated bore sighter in a few minutes, and it will give you a pretty good indication of whether your shit is right or not. And that is much shorter range than a 100 yard target.

 

[AuNEagle]

If you're tall target testing a hope you're using a rig like the badger or whatever frank uses and not just shooting

Since you asked, this is the scope fixture I'm using:

 

[Hegre]

I ignore the built in level and use their adjustable addon level which is much nicer.

 

[pmclaine]

The level is on the mount.....who cares what it reads.

Are the crosshairs level with gravity?

That's what matters.

 

[Hegre]

The level is on the mount.....who cares what it reads.

Are the crosshairs level with gravity?

That's what matters.

If you level the scope to the spuhr, then it is fine. I find it hard to read quickly, so I prefer the external one.

 

[AuNEagle]

Just to be clear, I do not plan to use the level on the Spuhr mount while shooting. I was just concerned that it was off level compared to everything else I was seeing. (The Spuhr bubble was off to the right from level, not sure if it was maxed out in that direction or not.)

 

[pmclaine]

If you level the scope to the spuhr, then it is fine. I find it hard to read quickly, so I prefer the external one.

How do you know your crosshairs are level? Because a flat on the scope says so?

Get in position behind the rifle with loose scope rings. Get as comfortable as you can behind the gun and find NPA on a plumb line

Sight in your vertical reference on the plumb line. Tighten scope rings.

I bet your level will be off but the scope will be on.

 

[scott5456]

I've seen a significant left lean in the level on all the Spuhr mounts. Really not great for what they cost and such an easy thing to get right. I was able to get an accurate level on the $100 add on Spuhr level that is slightly adjustable.

 

[AuNEagle]

How do you know your crosshairs are level? Because a flat on the scope says so?

Get in position behind the rifle with loose scope rings. Get as comfortable as you can behind the gun and find NPA on a plumb line

Sight in your vertical reference on the plumb line. Tighten scope rings.

I bet your level will be off but the scope will be on.

I didn't use a flat on the scope, the scope wasn't mounted on my rifle and I did use a plumb bob as stated in my original post.

My intent was to use the scope fixture to first get the Spuhr base leveled up. With the Spuhr base level, I then installed the scope and leveled the reticle to the plumb bob. I rechecked the reticle against the plumb bob multiple times while tightening the screws between the top and bottom halves of the mount. (FWIW, when the scope was still loose and had been initially adjusted to the plumb bob, I inserted the Spuhr wedge into the base and against the bottom of the reticle housing and the scope didn't move.) Now, with the scope squared up to the Spuhr base, I intend to do some tall target testing off the scope fixture and then move the base/scope to my rifle. My assumption is that if I have the scope properly leveled to the base, I shouldn't have to repeat this process once that package is installed on the rifle.

My original question about this part of the process is that once I thought I had the Spuhr base level, the bubble in the built-in Spuhr level disagreed. Hence the question about the accuracy of those built-in levels. I didn't know if I should be concerned about this discrepancy or not.

 

[Hegre]

How do you know your crosshairs are level? Because a flat on the scope says so?

Get in position behind the rifle with loose scope rings. Get as comfortable as you can behind the gun and find NPA on a plumb line

Sight in your vertical reference on the plumb line. Tighten scope rings.

I bet your level will be off but the scope will be on.

You mount the scope so that the plumb is perfect to the reticle while the bubble level is also dead center.

 

[b6graham]

You mount the scope so that the plumb is perfect to the reticle while the bubble level is also dead center.

These two things are not necessarily mutual

 

[Hegre]

These two things are not necessarily mutual

So you rotate them in relation to eachother until they line up…. Not complicated. If you want the rifle canted, adjust the bubble so it it level where you like the rifle, then level the scope to plumb while the bubble is level.
This, of course, requires an adjustable bubble level.

 

[Huskydriver]

So on my spuhrs like others have stated ignore the bubble at first. I make sure to level to reticle to gravity and then I play with the rubber shims that come with the mount behind the level retaining screw. Just a lil turn this way or that will move that level usually until its also leveled to the rifle/reticle with gravity just an FYI

 

[CoryT]

How do you know your crosshairs are level? Because a flat on the scope says so?

Get in position behind the rifle with loose scope rings. Get as comfortable as you can behind the gun and find NPA on a plumb line

Sight in your vertical reference on the plumb line. Tighten scope rings.

I bet your level will be off but the scope will be on.

The Spur uses the flat at the scope turret bottom to level the scope in the rings. That should be square to the adjustment screws in a reasonable quality scope. The crosshairs should be square to those adjustments. If it’s not, then it sort of depends on how you use the optic as to how you proceed. If you always hold elevation, then square the reticle. If you always dial, square the turret. If you use a mix, square the turret and see if the reticle is far enough off to cause a problem, if yes, get it repaired or replaced.

you can do the scope test on the fixture at any distance, but precision is improved by using the longest distance you can read the smallest adjustment increment.

 

[b6graham]

So you rotate them in relation to eachother until they line up…. Not complicated. If you want the rifle canted, adjust the bubble so it it level where you like the rifle, then level the scope to plumb while the bubble is level.
This, of course, requires an adjustable bubble level.

Adjustable bubble level is the key part missing in your first comment

 

[Hegre]

Adjustable bubble level is the key part missing in your first comment

Read post #7. Besides what I stated in #14 is perfectly simple to achieve with a fixed bubble.

 

[strikeeagle1]

Just sayin' & askin'. Small bubble levels are not as accurate as we might believe them to be; Arisaka's and Spuhr have wedges that can be used. Lately, I have been using this little Wixey digital level (with a magnetic base) about the milling machine squaring work into the vise etc; it's about $30 bucks, back lit and good to 0.1 degree, more so than any Starrett / Wheeler Level I can interpolate. Wonder why a small digital level has not been incorporated in to those scope mounts where bubble levels are presently used. It seems it could be downsized quite a bit, and as suggested for those that cant their rifles, zero out the cant perpendicular to earth and you would be good to go.

 

[b6graham]

Read post #7. Besides what I stated in #14 is perfectly simple to achieve with a fixed bubble.

Missed that. But yes their add on level is slick

 

[CK1.0]

I'm not sure about #2 (but sounds like if your math is good and you scale correctly it should be fine).

#1 is pretty easy though (you see it a lot in this particular game): why does the level built in to a $400 mount suck ass you say?

-> Premium pricing is the practice of keeping the price of a product or service artificially high in order to encourage favorable perceptions among buyers, based solely on the price. The practice is intended to exploit the (not necessarily justifiable) tendency for buyers to assume that expensive items enjoy an exceptional reputation, are more reliable or desirable, or represent exceptional quality and distinction. Moreover, a premium price may portray the meaning of better quality in the eyes of the consumer. - Wikipedia "pricing strategies"

I'm not saying a Spuhr mount is bad, I'm not and they're not. Just saying they're $400 because guys in our sport will pay $400...