March 19th, 2019

Gun Science: Engineers Plot Shots with Accelerometers

Texas Waterloo labs Youtube accelerometer gun .22 LR pistol test triangulation
A team of Texas engineers uses the principle of convolution to plot shot impacts. By triangulating data from multiple accelerometers, each shot’s exact point of impact can be plotted with great precision.

Waterloo Labs is a group of engineers from National Instruments and other self-declared “nerds” from Austin, Texas. These folks conducted an interesting demonstration using electronic accelerometers to plot bullet impacts from a suppressed Ruger MKIII .22LR pistol. The accelerometers respond to vibrations caused when the bullets hit a drywall target backer. By triangulating data from multiple accelerometers, each shot’s exact point of impact can be plotted with great precision. These point-of-impact coordinates are then fed into a computer and super-imposed into a Flash version of the Half-Life video game (which is projected on the drywall board). The end result is being able to “play” a video game with a real firearm.

triaxial accelerometerDo-It-Yourself Electronic Target System?
Now, we are NOT particularly interested in shooting Zombies in a video game. However, the technology has interesting potential applications for real shooters. Waterloo Labs has published the computer code, used to triangulate bullet impacts from multiple accelerometers. Potentially, a system like this could be built to provide display and scoring of long-range targets. Sophisticated electronic target systems already exist, but they use proprietary hardware and software, and they are very expensive. The Waterloo Labs experiment shows that shooters with some computer and electronic skills could build their own electronic scoring system, one that can be adapted to a variety of target sizes and materials.

In addition, we imagine this system could be utilized for military and law enforcement training. The walls of structures used for “live-fire” room-clearing exercises could be fitted with accelerometers so the bullet impacts could be plotted and studied. Then, later, the impact plots could be combined with a computer simulation so that trainees could “replay” their live-fire sessions, viewing the actual location of their hits (and misses).

Credit The Firearm Blog for finding this Waterloo Labs project.
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March 17th, 2019

Vihtavuori Explains Powder Grain Shapes

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

POWDER GRAIN SHAPES — What You Need to Know

The shape of powder grains has a profound effect on the performance of the powder charge, as it concerns both pressure and velocity. There are multiple powder shapes including flake, ball, and extruded or “stick” (both solid and perforated).

All Vihtavuori reloading powders are of the cylindrical, single-perforated extruded stick type. The differences in burning rate between the powders depend on the size of the grain, the wall thickness of the cylinder, the surface coating and the composition. Cylindrical extruded powders can also have multi-perforated grains. The most common types are the 7- and 19-perforated varieties. A multi-perforated powder grain is naturally of a much larger size than one with a single perforation, and is typically used for large caliber ammunition.

Other types of powder grain shapes include sphere or ball, and flake. The ball grains are typically used in automatic firearms but also in rifles and handguns. The ball grain is less costly to produce, as it is not pressed into shape like cylindrical grains. Flake shaped grains are typically used in shotgun loadings.

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

Web thickness in gunpowder terminology means the minimum distance that the combustion zones can travel within the powder grain without encountering each other. In spherical powders, this distance is the diameter of the “ball”; in flake powder it is the thickness of the flake; and in multi-perforated extruded powders it is the minimum distance (i.e. wall thickness) between the perforations.

The burning rate of powder composed of grains without any perforations or surface treatment is related to the surface area of the grain available for burning at any given pressure level. The change in the surface area that is burning during combustion is described by a so-called form function. If the surface area increases, the form function does likewise and its behavior is termed progressive. If the form function decreases, its behavior is said to be degressive. If the flame area remains constant throughout the combustion process, we describe it as “neutral” behavior.

The cylindrical, perforated powders are progressive; the burning rate increases as the surface area increases, and the pressure builds up slower, increasing until it reaches its peak and then collapses. Flake and ball grains are degressive; the total powder surface area and pressure are at their peak at ignition, decreasing as the combustion progresses.

So how does the shape affect pressure and muzzle velocity? In general, it can be said that powder that burns progressively achieves a desired muzzle velocity at lower maximum pressure than a powder that burns neutrally, not to mention a degressive powder. As grain size increases, the maximum pressure moves towards the muzzle, also increasing muzzle blast. Muzzle velocity and pressure can be adjusted by means of the amount of powder or loading density, i.e. the relationship between the powder mass and the volume available to it. As the loading density increases, maximum pressure grows.

Learn More with FREE Vihtavuori Reloading APP »

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders


This article originally appeared on the Vihtavuori Website.

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March 16th, 2019

A Beauty of a Beast — .50 BMG Falling Block Rifle (Amazing)

.50 BMG J.T. 50-caliber Smith breech block falling block custom rifle
.50 BMG J.T. 50-caliber Smith breech block falling block custom rifle

This is one amazing .50-caliber rifle. Along with the lever-actuated falling block, it has a massive swing-out breech block like you’d find on a field artillery piece. The action is so wide that the sights and scope are offset. You’ve heard of the “Beauty and the Beast”? Well here the Beast IS a Beauty….

View looking down at the action from above. Note the hinged Breech-Block.
.50 BMG J.T. 50-caliber Smith breech block falling block custom rifle

This extraordinary example of gunsmithing art was crafted by the late J.T. (Jack) Smith of Sudbury, Massachusetts. This unique .50-caliber rifle features an aircraft machine gun barrel cut down to 38-1/4″, and turned octagon to round (in the style of Schuetzen rifles). The round portion of the barrel is tapered with a heavy boss at the muzzle. The barrel is inlaid in gold on both left and right side top flats. Custom scope bases are fitted to the receiver and to the top of the barrel. These hold an externally adjusting Unertl 15X target scope in offset scope mounts.

.50 BMG J.T. 50-caliber Smith breech block falling block custom rifle

Huge Falling Block Receiver
The massive receiver (8″ long x 2-3/4″ wide x 3″ deep) is remarkable in design and construction. Machined from solid steel, the action incorporates several unique features. Note the hinged Howitzer-style breech block which swings to the right and mortises into the back of the receiver in the loading slot, providing a back-up for the falling block. We’ve never seen anything like that on any rifle. The one-piece floorplate/lever incorporates a Ruger No. 1-style latch which locks into the bottom of the trigger guard. The entire floorplate and lever retract downward. Firing is accomplished by means of a striker mounted in the hinged (swing-out) breech block. This is manually cocked with another lever on top of the breech block. Dropping the falling block activates the extractor which removes the spent case.

Offset Sights
This rifle features a custom-built, windage-adjustable offset front sight plus a custom-built vernier tang sight with aperture offset to the left side. The sights are offset to the left for a right-handed shooter, to correct for the extreme width of the receiver, allowing a more comfortable head position.

.50 BMG J.T. 50-caliber Smith breech block falling block custom rifle

(more…)

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March 10th, 2019

Tall Target Test — How to Verify Your Scope’s True Click Values

Scope Click Verify Elevation Tall Target Bryan Litz NSSF test turret MOA MIL

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).

Scope Click Verify Elevation Tall Target Bryan Litz NSSF test turret MOA MIL

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.


CLICK HERE to DOWNLOAD Tall Target Worksheet (PDF) »

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.”

Scope Tall Test level calibrationVerifying 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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March 5th, 2019

When ARs Fail — Busted Bolt Incident

AR15 AR-15 Bolt failure Broken AR Bolt Police Department

Our friend Dennis Santiago was recently conducting training for a Southern California Police Department. During a training session one of the unit’s AR15s stopped functioning. The problem — the bolt in the AR rifle broke in half. Dennis states: “They ran the gun dry, broke for lunch, shot it again. They don’t like that. I personally like to flood the bolt wet with lube on training days. It prevents stuff like this. Given that, it’s a simple remove-and-replace fix.”

AR15 AR-15 Bolt failure Broken AR Bolt Police Department

Here are some of the more interesting comments about this parts failure — an AR bolt that literally sheared in half:

“If I was a betting man [the steel] wasn’t made by Carpenter Steel. They are one of the few companies that use the correct [milspec-steel, C-158] called out on the drawing which they coincidentally developed. Most of the other companies that make [AR Bolts] use different steel with the same heat treat specification as what is called out which gives them the potential of being a little on the brittle side at the upper end of the tolerance. When it comes to the AR platform, bolts are probably the only part of the entire gun where I must admit to being a little bit of a brand snob.” David O’N.

[Editor’s Note: Actually Carpenter Steel does not make AR bolts. They are a steel supplier, and yes Carpenter did develop the original C-158 steel for AR bolts. Here is a contrary view, claiming that AISI 9310 Steel is actually stronger than milspec Carpenter C-158: 9310 Steel for AR Bolts.]

“Dry bolt and carrier shouldn’t cause that. Looks like a big pressure spike. What kind of ammo…?” Guy G.
Reply from Dennis: “55gr factory ammo.Piles of it.

“Is that the new two-piece bolt everyone’s been talking about LOL?” — Darren R.

“Let me guess…the PD called you in cause they didn’t know why it stopped going ‘pew pew’?” — Jim O.
Reply from Dennis: “I was there today for qualifications. It broke during the rifle phase. Simple enough to fish the bolt parts out of the action. The training didn’t miss a beat. I have an armory full of the things.”

Permalink Gunsmithing, Tactical, Tech Tip 14 Comments »
March 3rd, 2019

How Rimfire Ammo is Made — Federal and CCI Videos Show All

22 .22 Plinkster Youtube Video CCI Speer Rimfire Ammo Ammunition plant Lewiston Idaho

CCI and Federal Premium are both brands of Vista Outdoor. Most CCI rimfire is produced in Idaho, while other Federal-branded rimfire ammo is produced in Federal’s Anoka, Minnesota facilities. Here we feature videos from both CCI and Federal ammo plants. Watch and learn how rimfire ammo is made.

Field & Stream Tours Federal Ammo Plant in Minnesota
A reporter for Field & Stream recently got a chance to tour the Federal ammunition production facility in Anoka, Minnesota. This large plant produces both rimfire and centerfire ammunition. While touring the plant, the reporter was allowed to capture video showing the creation of .22 LR rounds from start to finish. This is a fascinating video, well worth watching.

Note to Viewers — After Starting Video, Click Speaker Icon to HEAR audio!

This revealing video shows all phases of .22 LR ammo production including cupping, drawing, annealing, washing, drying, head-stamping, priming, powder charging, bullet seating, crimping, waxing, inspection, and final packaging. We recommend you watch the video from start to finish. You’ll definitely learn some new things about rimfire ammo.

.22 LR Ammo Production in Idaho
Back in 2016, YouTuber 22Plinkster was able to tour the CCI Ammo plant in Lewiston, Idado. Here is the rimfire production video he produced.

The Manufacturing Process for .22 LR Rimfire Ammunition
Shooting Sports USA explains: “Rimfire cartridge cases are the oldest self-contained cartridge in existence, having been in continuous production since the mid-1850s. Rimfire cases are drawn from a thin piece of brass and formed with a hollow rim. A priming compound is then forced into the case using centrifugal force, where it is charged with powder and a bullet is seated in the mouth of the case. The case is then crimped around the bullet to ensure sufficient push and pull when the round is fired. When the firing pin strikes the thin brass rim of the case, the hollow rim is crushed and the primer is ignited.” Source: SSUSA.org 9/2/2017.

.22 LR ammunition photo
Photo courtesy BulkAmmo.com.

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February 26th, 2019

Range Kit Essentials — 12 Handy Items for Days at the Range

Range Kit Gear shellholder safety dozen essentials

The shooting season is now in full swing. When you head to the range you’ll want to be prepared. That means collecting all the gear you’ll need at the range. It’s easy to forget small, critical items, so we’ve provided a checklist of the small “extras” you should pack before you head out to the range. In addition to rifle, rests, ammo, targets, and cleaning gear, here are a dozen essentials you should include in your range bag.

Shell-Holder — If you don’t have calipers, you can use a shell-holder to check for excessive case expansion from hot loads. If a fired case doesn’t slip into the shell-holder easily, your load is definitely TOO HOT.

Extra Earplugs — Always use ear protection when shooting. We bring a 35mm film canister with extra sets of foam earplugs.

Hex Wrench or Screwdriver for action screws — Action screws can work loose with time. Always bring the appropriate hex wrench or screwdriver whenever you go to the range.

Small Wrench for Scope Rings — Check the tension of your scope base and ring fasteners before you go. Bring along a small Torx wrench for the ring screws (or other tool that fits your fasteners).

Normal and Under-sized Jags — It is often wise to use one-caliber undersize jags when applying solvent with cotton patches. You should have a couple sizes in your range kit.

Extra Batteries — Bring extra batteries for all your electronic gear — which can include chronograph, windmeter, digital camera, GPS etc.

Small Notebook and Pen or Pencil — Use the notebook to record chron data, log group sizes, and make notes about wind and weather conditions.

Adhesive dots — Bring a few sheets of adhesive dots (sold at office supply stores). Use small white or black dots as target pasters. Use larger red or orange dots as aiming points (target centers).

Folding Chair or Camp Stool — This comes in handy if you’re spotting for another shooter, or if you reload away from the firing line.

Water Bottle — You can’t shoot well if you’re dehydrated. Bring at least two quarts of water with you and keep a bottle at the bench.

Surveyors’ Tape and Wood Stakes — You can make inexpensive wind indicators using surveyors’ tape attached to the top of wood stakes.

Small Plastic Ruler — Use this to measure your group sizes. A transparent (see-through) ruler works best. Rulers are also useful for drawing lines on targets.

This list is not intended to be exclusive. There are many other items you may wish to include. Obviously bring safety glasses, and Sharpie-type pens are always handy to mark targets. We invite our readers to add other “essentials” to the list. The important thing is to plan ahead, packing your key items before you drive to the range.

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February 24th, 2019

Primer Pocket Rocket — Another Reason to Use Eye Protection

Primer Blown Gas defect winchester casehead

A few years back, Our friend Grant Guess had a “close encounter” with a bad primer. An apparently defective primer caused part of the casehead on one of his rounds to blow out. This, in turn, allowed high pressure gas to vent through the damaged primer pocket. Take a good look, boys and girls. This is yet another very good reason to wear safety glasses. The cartridge was a 6.5-06, handloaded in necked-down Winchester-headstamp .270 Win brass. Grant reports:

“I had a blow through between the primer and the primer pocket today. The action was really smoking and I got a face full of gas. This was a reasonably light charge. Thank God for safety glasses.

I should also mention that it appears there is a 3/64 hole that is halfway between the primer and the primer pocket. Like it burned a small jet hole through both of them.”

Could this happen to you? It just might. On seeing this damaged case, one of Grant’s Facebook friends, Chris D., observed: “Search the internet, you will see a lot of these pin hole ‘in the corner’ failures. Obviously Winchester has some issues with the LR primers.”

Careful Examination Reveals Apparent Primer Defect
After this incident, Grant examined the damaged case: “I pinned the flash hole and it is not over-sized or under-sized. The primer clearly has an area where it had a defect. At [50,000 CUP], it doesn’t take much of a defect to cause issues. There was a slight bit of pucker-factor on the next shot….”

Primer Blown Gas defect winchester casehead

Permalink Bullets, Brass, Ammo, Tech Tip 8 Comments »
February 22nd, 2019

MV on the Box? Why You Still Need to Chron Factory Ammo

muzzle velocity applied Ballistics MV chronograph

Why You CANNOT Rely on the MV Printed on the Ammo Box!
When figuring out your come-ups with a ballistics solver or drop chart it’s “mission critical” to have an accurate muzzle velocity (MV). When shooting factory ammo, it’s tempting to use the manufacturer-provided MV which may be printed on the package. That’s not such a great idea says Bryan Litz of Applied Ballistics. Don’t rely on the MV on the box, Bryan advises — you should take out your chrono and run your own velocity tests. There are a number of reasons why the MV values on ammo packaging may be inaccurate. Below is a discussion of factory ammo MV from the Applied Ballistics Facebook Page.

Five Reasons You Cannot Trust the Velocity on a Box of Ammo:

1. You have no idea about the rifle used for the MV test.

2. You have no idea what atmospheric conditions were during testing, and yes it matters a lot.

3. You have no idea of the SD for the factory ammo, and how the manufacturer derived the MV from that SD. (Marketing plays a role here).

4. You have no idea of the precision and quality of chronograph(s) used for velocity testing.

5. You have no idea if the manufacturer used the raw velocity, or back-calculated the MV. The BC used to back track that data is also unknown.

1. The factory test rifle and your rifle are not the same. Aside from having a different chamber, and possibly barrel length some other things are important too like the barrel twist rate, and how much wear was in the barrel. Was it just recently cleaned, has it ever been cleaned? You simply don’t know anything about the rifle used in testing.

2. Temperature and Humidity conditions may be quite different (than during testing). Temperature has a physical effect on powder, which changes how it burns. Couple this with the fact that different powders can vary in temp-stability quite a bit. You just don’t know what the conditions at the time of testing were. Also a lot of factory ammunition is loaded with powder that is meter friendly. Meter friendly can often times be ball powder, which is less temperature stable than stick powder often times.

3. The ammo’s Standard Deviation (SD) is unknown. You will often notice that while MV is often listed on ammo packages, Standard Deviation (normally) is not. It is not uncommon for factory ammunition to have an SD of 18 or higher. Sometimes as high as 40+. As such is the nature of metering powder. With marketing in mind, did they pick the high, low, or average end of the SD? We really don’t know. You won’t either until you test it for yourself. For hand-loaded ammo, to be considered around 10 fps or less. Having a high SD is often the nature of metered powder and factory loads. The image below is from Modern Advancements in Long Range Shooting: Volume II.

muzzle velocity applied Ballistics MV chronograph

4. You don’t know how MV was measured. What chronograph system did the manufacturer use, and how did they back track to a muzzle velocity? A chronograph does not measure true velocity at the muzzle; it simply measures velocity at the location it is sitting. So you need to back-calculate the distance from the chrono to the end of the barrel. This calculation requires a semi-accurate BC. So whose BC was used to back track to the muzzle or did the manufacturer even do that? Did they simply print the numbers displayed by the chronograph? What kind of chronograph setup did they use? We know from our Lab Testing that not all chronographs are created equal. Without knowing what chronograph was used, you have no idea the quality of the measurement. See: Applied Ballistics Chronograph Chapter Excerpt.

5. The MV data may not be current. Does the manufacturer update that data for every lot? Or is it the same data from years ago? Some manufacturers rarely if ever re-test and update information. Some update it every lot (ABM Ammo is actually tested every single lot for 1% consistency). Without knowing this information, you could be using data for years ago.

CONCLUSION: Never use the printed MV off a box of ammo as anything more than a starting point, there are too many factors to account for. You must always either test for the MV with a chronograph, or use carefully obtained, live fire data. When you are using a Ballistic Solver such as the AB Apps or Devices integrated with AB, you need to know the MV to an accuracy down to 5 fps. The more reliable the MV number, the better your ballistics solutions.

Permalink Bullets, Brass, Ammo, Shooting Skills, Tech Tip 1 Comment »
February 20th, 2019

Take Better Match and Gun Range Photos with Fill Flash

camera daylight fill flash shootingWe know you guys like taking photos of your rifles at the range. And, if you’re selling a rifle, scope, front rest, or rear bag, you need good photos to post in our Forum classifieds. Here’s a basic photography tip that can help you produce dramatically better photos. Use your camera’s ability to add “fill flash” even in daylight.

There’s plenty of light on a bright day. But bright light also means strong shadows. The shadows can leave parts of your subject literally in the dark. Daylight flash will help fill in those dark spots. In addition, if you are on a covered firing area, and want to include the range in your photo, you can benefit from using flash. This will prevent the foreground subject from being too dark while the downrange background is much too bright.

Photo without Flash

The photo above was taken without flash. As you can see, the rifle is too dark so details are lost. At the same time, the background (downrange) is over-exposed and washed out. The second photo below is taken with daylight flash. The difference is dramatic. Now you can see details of the rifle, while the background is exposed properly. Note how much easier it is to see the the targets downrange and the colors of the front rest. NOTE: these two photos were taken at the same time — just seconds apart.

Photo with Daylight “Fill-Flash”

Be sure to click on the larger versions of each photo.

How to Activate Daylight Flash
Most digital cameras have daylight flash capability. Some cameras have a separate setting for “auto fill flash”. On other cameras, you’ll have to set the camera to aperture priority and stop down the aperture to force the flash to fire. Read your camera’s manual. On many Canons, a menu that lets you set the “flash output”. For “fill flash” we like to set the flash at 30% to 50% output. This fills in the shadows sufficiently without “killing contrast” or creating too much reflection on shiny metal. Below is a photo taken with 30% flash output. Note the rich colors and how the exposure is balanced between foreground and background. Without flash the sky and target area would be “washed out”.


Here’s another tip for Canon owners. If you like deep, rich colors, use the “Vivid” setting in the effects menu. This punches up saturation and contrast.

Permalink - Articles, Tech Tip 2 Comments »
February 18th, 2019

READ THIS — Powder Storage — How to Avoid Problems

Western Powders Blog SAAMI Storage

SUMMARY: Powder can have a very long shelf life. You need to watch for changes in smell and color. A reddish tinge, almost like rust on the powder, is a bad sign, as is a foul odor, not to be confused with a normal chemical smell. Either of these signs indicate it is time to dispose of your powder by means other than shooting.

Ever wondered about the stability of the propellants in your reloading room? There are some important things you should know about powder storage, to ensure consistent powder performance and safety. On its website, Western Powders (vendors of Accurate, Norma, and Ramshot powders) published an informative Q & A series entitled Dear Labby: Questions for our Ballistics Lab. Here are some excerpts that pertain to powder storage and shelf life. Worried that your powder may be too old? Western’s experts explain how to check your propellants for warning signs.

Proper Powder Storage

Q: I live in southern Arizona where it is very hot. I am told powders will become unstable if stored in an area not air-conditioned. My wife says no powder or primers in the house. Can powder be stored in a refrigerator? What about using a fireproof safe? I would appreciate your ideas. — M.C.

Lab Answer: SAAMI guidelines are pretty clear on issues of storage. They recommend storing smokeless powder in containers that will not allow pressure to build if the powder is ignited — ruling out gun safes and refrigerators.

CLICK HERE to Read SAAMI Guidelines for Powder Storage (PDF)

In their original containers smokeless powder’s lifespan is quite long, even in your hot, arid climate, typically longer than the average handloader would need to store them. Stored safely in a garage or outbuilding, your powder should last years. If you see the powder developing a reddish tint, or giving off a foul odor, it is time to discard it.

Clumps in Powder Container

Q: I ordered some of your Accurate 1680 powder back about in December. I just now opened it … and it is full of clumps. My knowledge tells me that means moisture. Am I wrong? I just now broke the seal and it has been stored in a ammo can with desiccant packs around it and a dehumidifier running 14-16 hours a day. I can’t imagine this being my fault, if this does indicate moisture. I don’t know if the pink part on the label is suppose to be red or not, but it is definitely pink, so if it was red I am wondering if I was shipped an old container? I hope that this isn’t bad and I am stuck with it…

Lab Answer: All powder contains a certain amount of moisture. When the powder is stored or during shipping, it can go through temperature cycles. During the cycling, the moisture can be pulled to the surface and cause clumping. Clumping can also be caused by static electricity if too dry or the powder has limited graphite content. You can break up the clumps before metering and they shouldn’t be a problem. This will not affect the powder performance, so your product is fine. Accurate 1680 labels are designed in Pink. As a side note, specification for testing powder is at 70° F and 60% humidity.

(more…)

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February 17th, 2019

Don’t Kill the Chrono! Setting up Chronos to Avoid Stray Shots

chronograph placement, shooting chrony, chrono, advisory, tech tip

There is nothing more frustrating (or embarassing) than sending a live round into your expensive new chronograph. As the photo below demonstrates, with most types of chronographs (other than the barrel-hung Magnetospeed), you can fatally injure your expensive chrono if it is not positioned precisely.

When setting up a chrono, we always unload the rifle, remove the bolt and bore-sight to ensure that the path of the bullet is not too low. When bore-sighting visually, set up the rifle securely on the sandbags and look through the bore, breech to muzzle, lining up the barrel with your aim point on the target. Then (during an appropriate cease-fire), walk behind the chronograph. Looking straight back through the “V” formed by the sky-screens, you should be able to see light at the end of the barrel if the gun is positioned correctly. You can also use an in-chamber, laser bore-sighter to confirm the visual boresighting (see photo).

Laser boresighter chronograph

Adjust the height, angle and horizontal position of the chronograph so the bullet will pass through the middle of the “V” below the plastic diffusers, no less than 5″ above the light sensors. We put tape on the front sky-screen supports to make it easier to determine the right height over the light sensors.

Use a Test Backer to Confirm Your Bullet Trajectory
You can put tape on the support rods about 6″ up from the unit. This helps you judge the correct vertical height when setting up your rifle on the bags. Another trick is to hang a sheet of paper from the rear skyscreen and then use a laser boresighter to shine a dot on the paper (with the gun planted steady front and rear). This should give you a good idea (within an inch or so) of the bullet’s actual flight path through the “V” over the light sensors. Of course, when using a laser, never look directly at the laser! Instead shine the laser away from you and see where it appears on the paper.

chronograph set-up

Alignment of Chronograph Housing
Make sure the chrono housing is parallel to the path of the bullet. Don’t worry if the unit is not parallel to the ground surface. What you want is the bullet to pass over both front and rear sensors at the same height. Don’t try to set the chrono height in reference to the lens of your scope–as it sits 1″ to 2″ above your bore axis. To avoid muzzle blast interference, set your chronograph at least 10 feet from the end of the muzzle (or the distance recommended by the manufacturer).

chronograph laser sky screens

Rifles with Elevated Iron Sights
All too often rookie AR15 shooters forget that AR sights are positioned roughly 2.4″ above the bore axis (at the top of the front sight blade). If you set your bullet pass-through point using your AR’s front sight, the bullet will actually be traveling 2.4″ lower as it goes through the chrono. That’s why we recommend bore-sighting and setting the bullet travel point about 5-8″ above the base of the sky-screen support shafts. (Or the vertical distance the chronograph maker otherwise recommends). NOTE: You can make the same mistake on a scoped rifle if the scope is set on very tall rings, so the center of the cross-hairs is much higher than the bore axis line.

Laser boresighter chronograph

TARGET AIM POINT: When doing chrono work, we suggest you shoot at a single aiming point no more than 2″ in diameter (on your target paper). Use that aiming point when aligning your chrono with your rifle’s bore. If you use a 2″ bright orange dot, you should be able to see that through the bore at 100 yards. Using a single 2″ target reduces the chance of a screen hit as you shift points of aim. If you shoot at multiple target dots, place them in a vertical line, and bore sight on the lowest dot. Always set your chron height to set safe clearance for the LOWEST target dot, and then work upwards only.

Other Chronograph Tips from Forum Members:

When using a chronograph, I put a strip of masking tape across the far end of the skyscreens about two-thirds of the way up. This gives me a good aiming or bore-sighting reference that’s well away from the pricey bits. I learned that one the hard way. — GS Arizona

A very easy and simple tool to help you set up the chronograph is a simple piece of string! Set your gun (unloaded of course) on the rest and sight your target. Tie one end of the string to the rear scope ring or mount, then pull the string along the barrel to simulate the bullet path. With the string showing the bullet’s path, you can then easily set the chronograph’s placement left/right, and up/down. This will also let you set the chrono’s tilt angle and orientation so the sensors are correctly aligned with the bullet path. — Wayne Shaw

If shooting over a chrono from the prone position off a bipod or similar, beware of the muzzle sinking as recoil causes the front of the rifle to drop. I “killed” my first chronograph shooting off a gravel covered firing point where I’d not given enough clearance to start with and an inch or two drop in the muzzle caused a bullet to clip the housing. — Laurie Holland

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February 17th, 2019

Ballistics TIP: How Altitude and Air Pressure Affect Bullet Flight

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

Suunto AltimeterOne of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect.

It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet amsl), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.”

If you want to learn more about all aspects of External Ballistics, ExteriorBallistics.com provides a variety of useful resources. In particular, on that site, Section 3.1 of the Sierra Manual is reprinted, covering Effects of Altitude and Atmospheric Pressure on bullet flight.

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February 16th, 2019

If You’re Not Using Wind Flags You’re Throwing Away Accuracy


Forest of Windflags at World Benchrest Championships in France in 2011

There’s a simple, inexpensive “miracle device” that can cut your groups in half. If you’re not using this device, you’re giving away accuracy. The “miracle device” to which we refer is a simple wind indicator aka “windflag”. Using windflags may actually improve your accuracy on target much more than weighing charges to the kernel, or spending your life savings on the “latest and greatest” hardware.

Remarkably, many shooters who spend $3000.00 or more on a precision rifle never bother to set up windflags, or even simple wood stakes with some ribbon to show the wind. Whether you’re a competitive shooter, a varminter, or someone who just likes to punch small groups, you should always take a set of windflags (or some kind of wind indicators) when you head to the range or the prairie dog fields. And yes, if you pay attention to your windflags, you can easily cut your group sizes in half. Here’s proof…

Miss a 5 mph Shift and You Could DOUBLE Your Group Size

The table below records the effect of a 5 mph crosswind at 100, 200, and 300 yards. You may be thinking, “well, I’d never miss a 5 mph let-off.” Consider this — if a gentle 2.5 mph breeze switches from 3 o’clock (R to L) to 9 o’clock (L to R), you’ve just missed a 5 mph net change. What will that do to your group? Look at the table to find out.

shooting wind flags
Values from Point Blank Ballistics software for 500′ elevation and 70° temperature.

Imagine you have a 6mm rifle that shoots half-MOA consistently in no-wind conditions. What happens if you miss a 5 mph shift (the equivalent of a full reversal of a 2.5 mph crosswind)? Well, if you’re shooting a 68gr flatbase bullet, your shot is going to move about 0.49″ at 100 yards, nearly doubling your group size. With a 105gr VLD, the bullet moves 0.28″ … not as much to be sure, but still enough to ruin a nice small group. What about an AR15, shooting 55-grainers at 3300 fps? Well, if you miss that same 5 mph shift, your low-BC bullet moves 0.68″. That pushes a half-inch group well past an inch. If you had a half-MOA capable AR, now it’s shooting worse than 1 MOA. And, as you might expect, the wind effects at 200 and 300 yards are even more dramatic. If you miss a 5 mph, full-value wind change, your 300-yard group could easily expand by 2.5″ or more.

If you’ve already invested in an accurate rifle with a good barrel, you are “throwing away” accuracy if you shoot without wind flags. You can spend a ton of money on fancy shooting accessories (such as expensive front rests and spotting scopes) but, dollar for dollar, nothing will potentially improve your shooting as much as a good set of windflags, used religiously.

Which Windflag to buy? Click Here for a list of Vendors selling windflags of various types.

Aussie Windflag photo courtesy BenchRestTraining.com (Stuart and Annie Elliot).

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February 15th, 2019

DIY Brilliance — Forum Member Builds His Own Front Rest

AKShooter front rest F-Class Dasher 6mm Alaska
AKShooter front rest F-Class Dasher 6mm Alaska

AKShooter front rest F-Class Dasher 6mm AlaskaYou have to admire someone with serious do-it-yourself skills. Not just hammer and nail skills, but formidable design and fabrication skills. Well Forum Member Dave D. (aka “AKShooter”) has a DIY skill set that might put some trained machinists to shame. You see, “DIY Dave” crafted his own pedestal front rest from scratch, using his own design and about $100.00 in materials (not counting the Edgewood front bag). Dave estimates he put 20 hours of labor into the project, but the end result was worth it: “This Do-It-Yourself rest drives like a dream. I’ve played with the Caldwell and a Sinclair, they have nothing on this one.”

Dave tells us: “Here is my Do-It-Yourself front rest. I wanted to show other folks who are handy that a solid front rest is doable with a bit of time — and you don’t need to spend $1000.00. (You could say this is a design for shooters with more time than money.) This is for F-Class. I was originally overwhelmed by the equipment needed, so I decided to make my own rest. I didn’t have the money for a SEB or Farley Coaxial. This is what I’ll run this season (my second as an F-Class competitor).”

(more…)

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February 13th, 2019

GUN INFO 101 — Headspace Defined and Illustrated

Ultimate Reloader Brownells headspacing go gage gauge barrel gunsmithing
This illustration shows headspace measurement for the popular .308 Winchester cartridge, which headspaces on the shoulder. Image copyright 2015 Ultimate Reloader.

In this Brownells Tech Tip, Brownells gun tech Steve Ostrem explains what headspace is and why it’s one of the most critical measurements for nearly all firearms. Even if you’re an experienced rifle shooter, it’s worth watching this video to refresh your understanding of headspace measurements, and the correct use of “GO” and “NO-GO” gauges.

Headspace Definition
In firearms, headspace is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt. Used as a verb, headspace refers to the interference created between this part of the chamber and the feature of the cartridge that achieves the correct positioning. Different cartridges have their datum lines in different positions in relation to the cartridge. For example, 5.56x45mm NATO ammunition headspaces off the shoulder of the cartridge, whereas .303 British headspaces off the forward rim of the cartridge.

If the headspace is too short, ammunition that is in specification may not chamber correctly. If headspace is too large, the ammunition may not fit as intended or designed and the cartridge case may rupture, possibly damaging the firearm and injuring the shooter. (Source: Wikipedia)

Forster Headspace diagram belted magnum rimfire

Go gauge gage NOGO no-go field gaugesHeadspace Gauges
Headspace is measured with a set of two headspace gauges: a “Go” gauge, and a “No-Go” gauge. Headspace gauges resemble the cartridges for the chambers they are designed to headspace, and are typically made of heat-treated tool steel. Both a “Go” and a “No-Go” gauge are required for a gunsmith to headspace a firearm properly. A third gauge, the “Field” gauge, is used (as the name implies) in the field to indicate the absolute maximum safe headspace. This gauge is used because, over time, the bolt and receiver will wear, the bolt and lugs compress, and the receiver may stretch, all causing the headspace to gradually increase from the “factory specs” measured by the “Go” and “No-Go” gauges. A bolt that closes on “No-Go” but not on “Field” is close to being unsafe to fire, and may malfunction on cartridges that are slightly out of spec. (Source: Wikipedia)

To learn more, read Brownell’s longer article Headspace Gauges and How to Use Them. Among other things, this explains the relative lengths of “Go”, “No-Go”, and “Field” gauges. The “Field” is actually the longest: “The GO gauge corresponds to the SAAMI (Sporting Arms & Ammunition Manufacturer’s Institute) minimum chamber length, while the FIELD gauge usually matches the maximum chamber depth, or slightly less. NO-GO gauges are an intermediate length between minimum and maximum, that, technically, is a voluntary dimension. A firearm that closes on a NO-GO gauge and does not close on a FIELD gauge may not give good accuracy and may have very short cartridge case life from the ammunition re-loader’s standpoint.”

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February 12th, 2019

Monitor Barrel Heat with Handy Temp Strips

Barrel Heat Temp Temperature gauge strip McMaster Carr

You never want your barrel to get too hot. Accuracy suffers when barrels over-heat, and excessive heat is not good for barrel life. So how do you monitor your barrel’s temperature? You can check if the barrel is “warm to the touch” — but that method is not particularly precise. There is a better way — using temperature-sensitive strips. McMaster.com (an industrial supply house) offers stick-on temp strips with values from 86° F to 140° F. A pack of ten (10) of these strips (item 59535K13) costs $12.16 — so figure it’ll cost you about $1.20 per barrel for strips. That’s cheap insurance for your precious barrels. For best barrel life, try to stay under 120 degrees F.

Barrel Heat Temp Temperature gauge strip McMaster Carr

Forum member Nomad47 says: “I have temperature strips (bought at McMaster-Carr) on all my barrels. I try not to shoot when the barrel gets to 122 degrees or higher[.]” Here are photos of the McMaster-Carr temp strips on Nomad47’s customized Savage.

Barrel Heat Temp Temperature gauge strip McMaster Carr

Bad things can happen if your barrel gets too hot. First, with some barrels, the point of impact (POI) will shift or “walk” as the barrel heats up excessively. Second, even if the POI doesn’t change, the groups can open up dramatically when the barrel gets too hot. Third, if the barrel is very hot, the chamber will transfer heat to your loaded cartridge, which can lead to pressure issues. Finally, there’s considerable evidence that hot barrels wear out faster. This is a very real concern, particularly for varmint shooters who may shoot hundreds of rounds in a day. For this reason, many varminters switch among various guns, never letting a particular barrel get too hot.

Neconos.com offers Bar-L Temp Strips that visually display heat readings from 86 to 140 degrees. Think of these strips as compact, unbreakable thermometers. With adhesive backing, they can also be used to monitor barrel heating. Put a strip on the side of the barrel and the barrel’s temp will be indicated by a stripe that changes from black to green. There is also a “general purpose” strip that reads to 196 degrees (bottom row). The Benchrest strip (86F to 140F) is in the middle. Bar-L temp strips cost $9.00, or $25.00 for a 3-pack.

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February 9th, 2019

Bet You Ain’t Seen This Before — Barrel-Indexing Rimfire Action

Bill Myers Indexing Action

The late Bill Myers was recognized as one of greatest rimfire gunsmiths who ever lived. Myers crafted many match-winning, record-setting rimfire benchrest rigs. Here we feature one of Bill’s most interesting creations — a clamping action that allows a rimfire barrel to be indexed (rotated) around the bore axis.

Bill was a creative thinker, and his own exhaustive testing has convinced him that barrel indexing can enhance accuracy in rimfire benchrest guns. Myers did acknowledge that, particularly with a very good barrel, the advantages of indexing may be subtle, and extensive testing may be required. Nonetheless, Myers believed that indexing could improve rimfire accuracy.

Indexing with the Myers’ Clamping Action
To index the barrel, Myers simply loosens the three clamping-bolts and rotates the barrel in the action. Because there is no thread to pull the barrel in or out, the headspace stays the same no matter how much the barrel is rotated. In other words you can rotate the barrel to any position on the clockface and the headspace remains unchanged.

Bill Myers Indexing Action
Bill Myers Indexing Action

The Challenge of Barrel Indexing
cone breech bill myers rimfire indexable actionWith a conventional barrel installation, employing a shoulder with a threaded tenon, it is difficult to index the barrel. Even with a cone breech (photo right) that eliminates the problem of extractor cuts, you’d have to use shims to alter the barrel index position, or otherwise re-set the shoulder each time you screwed the barrel in further.

Clamping Action Allows Barrel to Be Rotated to Any Position
Bill has come up with a masterful solution to barrel indexing. He designed and built his own prototype custom action that clamps the barrel rather than holding it with threads. The front section of the action is sliced lengthways, and then clamped down with three bolts. A special bushing (the gold-color piece in photos) fits between the barrel and the action. By using bushings of different inside diameters, Bill can fit any barrel up to an inch or so diameter, so long as it has a straight contour at the breech end. To mount the barrel, Bill simply places the fitted bushing over the barrel end-shank, then slips the “sleeved” barrel into the front end of the action. Tighten three bolts, and the barrel is secure.

Bill Myers Indexing Action

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February 7th, 2019

Budget Hauler — Transport Your Gear with $56 Welding Cart

Welding Cart Range Cart

Creedmoor Sports Range Cart CRC-1The Berger SW Nationals is coming up in a couple weeks. At that match, the sling shooters and F-Class competitors need to haul lots of gear from parking lot to the firing line, and then move from yardage to yardage. Along with their rifles, shooters need to bring mats, front rests or bipods, spotting scopes (with stands), rear bags, ammo boxes, log sheets, tool kits, and heavy coats (for the sling shooters).

To do the hauling, you can certainly purchase a factory-made, purpose-built cart that folds up and has all the bells and whistles. The Creedmoor Sports CRC-1 (photo right) is a proven, quality product that works great. You’ll find these used by top shooters at Camp Perry. But the Creedmoor CRC-1 cart costs $499.95. For a fraction of that price ($55.99), plus a few dollars more for do-it-yourself enhancements, you can have a heavy-duty cart that will haul all your gear just fine, though it doesn’t fold up. In the top photo is a Harbor Freight Welding Cart we saw at the Berger Southwest Nationals. This rig is carrying a rifle in hard gun case, bipod, folding chair, shooting mat, tripod, spotting scope, rear sand-bag, and ammo box — that’s a lot of gear!

Welding Cart Range CartWelding Cart Range Cart

Check out the Harbor Freight Welding Cart, item #65939. This cart is ON SALE right now for just $59.99. Overall size is 29-1/2″ L x 20″ W x 49″ H, and width between side rails is 18″. The wheels (with tires) are 20 3/4″ in diameter for smooth rolling. Consider that, if you made your own cart from scratch you could easily pay $30.00 or more just for the large-diameter wheels and axle. Do note — this cart has air-filled tires. Be sure to inflate before you go to the Range!

This Cart is now on sale for just $55.99 — GREAT DEAL!

As sold, the Harbor Freight Welding Cart can benefit from upgrades for range use. But with a few bungee cords (and some creativity), the cart can be adapted pretty easily to hauling your gun gear. If you want to enhance the basic cart, it’s easy to add plastic side-panels on the bottom unit, and fit a barrel-holding system on the cross-tube. This ensures rifles and gear won’t flop forward. (A small piece of wood under the bottom panel provides a bit of extra lift that will keep the bottom plate out of the dirt and gravel.)

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February 3rd, 2019

Scope Mounting — How to Avoid That Rude Poke in the Eye

Kirsten Weiss Video YouTube Scope Eye Relief

This helpful video from our friend Kirsten Joy Weiss explains how to avoid “scope bite”. This can occur when the scope, on recoil, moves back to contact your forehead, brow, or eye socket area. That’s not fun. While common sense tells us to avoid “scope bite” — sooner or later this happens to most shooters. One viewer noted: “I have come close. I had a Win Model 70 in .375 H & H Mag and I was shooting over a large rock in a strange position. The scope hit my eye glasses hard enough to bend the wire frames and cause a little pain on the bridge of the nose from the nose piece. [That] made a believer out of me.”

Kirsten offers a good basic principle — she suggests that you mount your rifle-scope so that the ocular (eyepiece) of the scope is positioned at least three inches or more from your eyeball when you hold the rifle in your normal shooting position. From a technical standpoint, optical eye relief is a property of the scope, so you want to purchase an optic that offers sufficient optical eye relief (meaning that it allows you to see the full circle of light with your head at least three inches from the eyepiece). Then you need to position the optic optimally for your head/eye position when shooting the rifle — with at least three inches of eyeball-to-scope separation (i.e. physical eye relief).

NOTE: You should mount the scope to provide adequate eyeball-to-scope separation for the actual position(s) you will be shooting most of the time. For an F-TR rig, this will be prone. For a hunting rifle, your most common position could be sitting or standing. Your head position will vary based on the position. You can’t assume the scope placement is correct just because it seems OK when you are testing or zeroing the gun from the bench. When shooting from a prone or kneeling position you may find your eye considerably closer to the eyepiece.

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