Many shooters are familiar with ballistics tables, weather programs, and even wind meters for smart devices, but few may know about a very handy Leveling Tool that comes factory-installed on Apple iPhones. The leveling function is a little-known option in Apple’s Compass App. It works well for a multitude of tasks.
There are a numerous reasons that a leveling tool should be in every rifleman’s range bag. From leveling optics during mounting to figuring out how much extra compensation is going to be required for a tricky angled shot, knowing just how far off things are from plumb can go a long way towards realizing success in the field.
This writer has used the leveling app on his iPhone to level a rifle on a rest while at the range. It definitely worked for “field expedient” leveling duties. That’s especially important for long-range applications. Just one degree of cant (tilt) can move your point of impact 7 inches at 1000 yards.
Of course, the iPhone level doesn’t use an actual bubble to find angles. Rather, it relies on the device’s sophisticated accelerometer to do so, and with a great degree of accuracy. Navigating to the level is done by first selecting the Compass App, at which point the device will need to be calibrated by rotating it a full 360 degrees. Once the compass is fully calibrated, simply make right swipe gesture to bring up the level — it will start operating immediately.
From there, use is intuitive and easy, like most iPhone Apps. Switching from horizontal plane to vertical is done by simply changing the physical axis of the phone. How do you know when you’ve got things just right — well the entire lower half of the screen turns green when everything is perfectly level. You’ll also see a zero° read-out, like this:
Bottom Line: If you already own an iPhone, you should definitely give this App a try. The price is right (free), and for a wide variety of tasks the iPhone Level App is actually pretty handy.
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Have you recently purchased a new scope? Then you should verify the actual click value of the turrets before you use the optic in competition (or on a long-range hunt). While a scope may have listed click values of 1/4-MOA, 1/8-MOA or 0.1 Mils, the reality may be slightly different. Many scopes have actual click values that are slightly higher or lower than the value claimed by the manufacturer. The small variance adds up when you click through a wide range of elevation.
In this video, Bryan Litz of Applied Ballistics shows how to verify your true click values using a “Tall Target Test”. The idea is to start at the bottom end of a vertical line, and then click up 30 MOA or so. Multiply the number of clicked MOA by 1.047 to get the claimed value in inches. For example, at 100 yards, 30 MOA is exactly 31.41 inches. Then measure the difference in your actual point of impact. If, for example, your point of impact is 33 inches, then you are getting more than the stated MOA with each click (assuming the target is positioned at exactly 100 yards).
How to Perform the Tall Target Test
The objective of the tall target test is to insure that your scope is giving you the proper amount of adjustment. For example, when you dial 30 MOA, are you really getting 30 MOA, or are you getting 28.5 or 31.2 MOA? The only way to be sure is to verify, don’t take it for granted! Knowing your scopes true click values insures that you can accurately apply a ballistic solution. In fact, many perceived inaccuracies of long range ballistics solutions are actually caused by the scopes not applying the intended adjustment. In order to verify your scope’s true movement and calculate a correction factor, follow the steps in the Tall Target Worksheet. This worksheet takes you thru the ‘calibration process’ including measuring true range to target and actual POI shift for a given scope adjustment. The goal is to calculate a correction factor that you can apply to a ballistic solution which accounts for the tracking error of your scope. For example, if you find your scope moves 7% more than it should, then you have to apply 7% less than the ballistic solution calls for to hit your target.
NOTE: When doing this test, don’t go for the maximum possible elevation. You don’t want to max out the elevation knob, running it to the top stop. Bryan Litz explains: “It’s good to avoid the extremes of adjustment when doing the tall target test.I don’t know how much different the clicks would be at the edges, but they’re not the same.”
Should You Perform a WIDE Target Test Too?
What about testing your windage clicks the same way, with a WIDE target test? Bryan Litz says that’s not really necessary: “The wide target test isn’t as important for a couple reasons. First, you typically don’t dial nearly as much wind as you do elevation. Second, your dialed windage is a guess to begin with; a moving average that’s different for every shot. Whereas you stand to gain a lot by nailing vertical down to the click, the same is not true of windage. If there’s a 5% error in your scope’s windage tracking, you’d never know it.”
Verifying Scope Level With Tall Target Test
Bryan says: “While setting up your Tall Target Test, you should also verify that your scope level is mounted and aligned properly. This is critical to insuring that you’ll have a long range horizontal zero when you dial on a bunch of elevation for long range shots. This is a requirement for all kinds of long range shooting. Without a properly-mounted scope level (verified on a Tall Target), you really can’t guarantee your horizontal zero at long range.”
NOTE: For ‘known-distance’ competition, this is the only mandatory part of the tall target test, since slight variations in elevation click-values are not that important once you’re centered “on target” at a known distance.
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Here’s a cool product that can help you level your front rest and rear bag, level your scope, align your target frame, and perform a myriad of tasks around the house. The Digital Angle Cube (aka Electronic Level and Protractor Gauge) is basically a high-tech level that gives you exact angular read-outs to within 0.2 degrees. That’s a lot more precise than any bubble level.
Numerous Shooting-Related Applications
For you position shooters who like to run angled sights, this tool will help you set the rear sight and front tower to exactly the same angle. For High Power guys with 3-way and 4-way adjustable buttstocks, this digital angle gauge can help you quickly and precisely set buttstock angle and cast-off. Even tactical shooters and long-range hunters can use this device to confirm exact shot angle, with greater precision than a plastic protractor or even an expensive Angle Degree Indicator (ADI). Heck you can even use the thing as an anti-cant device (if you don’t mind the extra weight). We’re sure that our clever readers can find even more uses for a digital angle read-out tool.
The Digital Angle Tool sells on Amazon.com for $29.50. It comes with magnets on the sides so you can attach the tool to any ferrous metal surface for a “hands-free” reading. You can find similar devices in hardware and home improvement stores. One of these square, magnet-equipped electronic protractor/levels is made by INSIZE. The illustration below shows how the INSIZE gauge can be used in the field.
Story Sourced by Edlongrange.
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Eleven-Time NRA National High Power Champion David Tubb knows a bit about long-range shooting. One of the key factors in long-range accuracy is making sure that the tilt/cant of your rifle does not change throughout your shot string. In the clip below, the first in McMillan’s Master Class Video series, David Tubb explains the importance of keeping your rifle level. He explains that, at 1000 yards, your Point of Impact can change dramatically by canting the rifle either right or left. David states that, when shooting at 1000 yards, if your rifle is level and your shot is centered-up on a 72″ (six-foot) square target, you can actually put your next shot OFF PAPER by canting your rifle. That means you can move Point of Impact (POI) three feet or more, just by canting your rifle! Bryan Litz confirms Tubb’s observation. Bryan tells us that, as a general rule of thumb (for common cartridges), a 1° cant will produce five (5) inches of lateral displacement at 1000 yards. Thus, if you cant your rifle just 8°, the POI would move 40″ from the center of the target, putting the shot off the edge of a 72″-wide target.
David explains that, after one of his students has made two or three 1000-yard, X-Ring hits with a LEVEL rifle, “then I’ll have him take his rifle, and cant it to the right. I’ll have him shoot a shot. He will MISS the six-foot-square frame off to the right. Then I’ll have him cant his gun to the left and shoot another shot. He will miss the six-foot-square frame to the left.”
Rifle Hold and Canting — Consistency Counts Remember that you must maintain the exact same amount of rifle cant from shot to shot. Yes, some iron sights shooters do tilt their rifle slightly to achieve a better hold or to index their sights better. However, these shooters do not change the tilt from shot to shot — the amount of cant remains the same on every shot.
When shooting prone with a scoped rifle it’s probably best to keep the rifle dead level, with the scope’s vertical crosshair straight up and down. Use a rifle-mounted bubble level to maintain a level hold, and avoid canting the gun either to the left or to the right. Affordable bubble levels that mount to your scope or scope rail can be purchased from Brownells and other vendors, starting at about $15.00.
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Experienced marksmen know they should keep their rifles level when shooting. But they may not understand exactly what happens if they allow their rifle to be canted (tilted left or right), even a few degrees. While the physics are complicated to explain, here’s what you need to know: if you cant your rifle to the left, your shots will impact to the left, and lower, than your point of aim. Likewise, if you cant your rifle to the right, your bullets will impact low and right.
Effects of Rifle Canting
The effects of rifle canting are explained in great detail on the Long Shot Products Ltd. website. There, you’ll find a technical discussion of the Physics of Rifle Canting, plus a page with Sample Targets shot with canted rifles.
Referring to the above illustration, the Long Shot Products article explains: “Notice how the trajectory of the vertical hold stays within the vertical plane, so when the projectile drops, it drops into the line of sight and down to the center of the target. The trajectory of the cant hold does not achieve the same height as the trajectory of the vertical hold and the projectile diverges from the line of sight, thereby missing the target.”
The Long-Shot article makes two other important points. First, cant error increases with distance, and second, cant-induced windage errors are worsened by mounting your scope high above the bore axis:
“This component of cant error becomes more significant at more distant targets due to the increased original included angle between the line of sight axis and the bore axis (more elevation compensation) at the vertical hold.”
“Use of large-diameter objective scopes, mounted high off the barrel, exacerbates the cant error problem. To keep the scope elevation knobs centered for maximum adjustment, precision shooters sometimes use elevation-compensated scope mounting rings or bases. Although this solves the adjustment problem, it greatly exaggerates cant error because the distance between the bore axis and the line of sight axis increases and the included angle between the sight axis and the bore is larger, producing more windage error when canting.”
Test Targets Reveal Cant Errors
The Long Shot Products Ltd. website also displays actual Test Targets showing the effects of canting error. These targets were shot with air rifles and rimfire rifles, but the same effects can and will occur with centerfire rifles. Shown below is a target shot at 50 yards with a Feinwerkbau .22LR match rifle using RWS Match ammo (1012 fps MV). As you can see, canting the rifle 20 degrees to the left produced a huge movement of the point of impact. The shots from the canted rifle impacted 1.81″ Left, and 0.6″ below the point of aim.
Surgeon Rifles has engineered new, heavy-duty scope rings with unique features. First, the rear ring comes with a bubble level integrated into the top half. This smart invention eliminates one other pricey accessory you’d otherwise need to add separately. The new Surgeon rings are made of high-grade 7075 T6 Aluminum so they are strong yet light. The “wide-body” design offers a full 0.950″ of clamping surface (front to back), secured by three vertical hex-head fasteners per side. The rings will be offered in a variety of heights, from .875″ to 1.125″, in both 30mm and 34 diameters. A 0.625″-wide steel version is planned for later release. Ring sets will cost $199.00 and that includes the bubble level.
Surgeon uses 9-axis machining to ensure exact alignment of ring center with ring base. Preston Pritchett, Surgeon’s owner, explains: “The bottom of the ring is machined at the same time as the bore for the scope on a 9 axis machine. This is done in one operation to ensure that the bore is parallel with the bottom of the ring. We checked another brand and found that they were off .0025″ in .625 inch. We checked ours and found it to be within .0003 in .950.” These rings are very carefully designed and crafted to align square on the rail. Many Weaver-style rings have a sloppy fit on the rail so they can clamp slightly differently from one installation to the next. Surgeon uses alignment pins to ensure its rings clamp properly: “The silver pins you see are 1/8 dowel pins that keep the clamp square to the ring and at the right height.”
For more info on these rings, or to place an order, visit SurgeonRifles.com, or call Preston Pritchett at (405) 567-0183. Surgeon plans to be shipping ring sets in various sizes within three weeks.
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Many shooters are familiar with ballistics tables, weather programs, and even wind meters for smart devices, but few may know about a very handy Leveling Tool that comes factory-installed on Apple iPhones. The leveling function is a little-known option in Apple’s Compass App. It works well for a multitude of tasks.
Verifying Scope Level With Tall Target Test
Remember that you must maintain the exact same amount of rifle cant from shot to shot. Yes, some iron sights shooters do tilt their rifle slightly to achieve a better hold or to index their sights better. However, these shooters do not change the tilt from shot to shot — the amount of cant remains the same on every shot.
