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March 13th, 2024

How Human Hearing Works — And Effective Hearing Protection

hearing protection inner ear anatomy science hearing medical electronic muffs earplugs

hearing protectionAll shooters, even rimfire enthusiasts, should always wear ear protection when at the range. A typical rifle gunshot is very loud — in the region of 140 to 170 decibels (the pain threshold is 130-140 db). Without ear protection, you can permanently damage your hearing during a single shooting session. We all know older shooters who are partially deaf, or who suffer from Tinnitus, because they didn’t use earplugs or muffs when they were younger.

How Humans Hear Sounds — Amazing Video Reveals All
The human sense of hearing involves multiple delicate internal membranes, bones, organs, and nerves. Shooters understand the importance of protecting their hearing, but they may not understand the bio-mechanics of human hearing. We hear sounds through Auditory Transduction. Sound waves vibrate the ear drum (tympanic membrane), but that is only the beginning. These vibrations are passed along via tiny rocker-arm-like bones to be “processed” in a spiral chamber, the cochlea.

This remarkable VIDEO explains how humans hear sounds. We strongly recommend you take the time to watch and learn. The hearing you save may be your own!

Click Speaker Icon to turn on the video’s soundtrack.

Vibrations moving through the cochlea are separated into frequencies and then sent as neural messages to the brain. It is an astonishingly complex process, one that truly seems miraculous when you examine the bio-engineering involved. In the Video above, the process of human Auditory Transduction is explained and illustrated with 3D animation. You really should watch this amazing video. By the end you will have a new-found appreciation for your ability to hear.

hearing protection inner ear anatomy science hearing medical electronic muffs earplugs

Every shooter should own a pair of Electronic muffs, even if you prefer shooting with earplugs and/or standard muffs. Electronic muffs are great when you are spotting for other shooters or are working near the firing line. They let you hear ordinary conversations while still providing vital hearing protection. You can also wear ear-plugs under muffs for extra sound attenuation.

shooting ear protection nrr 33 ear plugs howard leightPlugs PLUS Ear-Muffs — The Benefits of “Doubling-Up” Your Hearing Protection
According to OHS Online: “The combined attenuation of an ear plug and an ear muff is not simply the algebraic sum of the performance of each individual protector. This is due to an acoustic and vibratory interaction between the ear muff and the ear plug that causes them to behave together as a system rather than as independent hearing protectors.

Generally speaking, when you combine two hearing protectors, ear muffs over ear plugs, you can expect an increase [in noise reduction] of between 3 and 10 dB over the higher-performing hearing protector. OSHA [now advises] 5 dB as the [typical] benefit offered by combining hearing protectors.” Source: OHSonline.com

Ear diagram courtesy Siemens Medical Solutions.

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March 11th, 2024

Shooting Factory Ammo? Find the True MV Speed in YOUR Rifle

muzzle velocity applied Ballistics MV chronograph

If you are planning to shoot a PRS match with factory ammo or use factory ammo when hunting, you should definitely check the ammo velocity in YOUR rifle. Otherwise your ballistics come-up tables could be all wrong. It’s not uncommon to find that the actual velocity in YOUR gun is NOT the same as the listed velocity on the ammunition package. We explain why in today’s article…

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.

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.

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March 10th, 2024

Cutaway Cartridges — Take a Peek INSIDE Loaded Ammunition

sliced cutaway ammo ammunition FOG diagram

Here’s something you don’t see every day — the inside of loaded cartridges, sliced halfway through. This lets you see how bullet core, jacket, cartridge case, powder, and primer all fit together. Give credit to the folks at FOG Ammunition for creating this interesting series of cut-through ammo images. We show four cartridges here: the .308 Winchester, 9mm Luger, 300 BLK, and .50 BMG. You’ll find two more (the .223 Remington and .45 ACP) at www.FogAmmo.com.

sliced cutaway ammo ammunition FOG diagram

This .308 Winchester model took on a different approach by only cutting the brass case and displaying the full bullet, primer and powder load. A spec amount of powder was used to create the model powder form. An estimated 10% volume was added during the forming process, along with an undetermined amount of air pockets.

sliced cutaway ammo ammunition FOG diagram

This bisection is a 9mm Luger Jacketed Hollow Point round with flake powder held together with super glue. After this self-defense round was cut by a trained professional the round was polished by hand. This might look like stick powder, but those are in fact flakes stacked up in cross-section. Designed in 1901 by Georg Luger, this popular cartridge is used by civilians, military, and law enforcement.

sliced cutaway ammo ammunition FOG diagram

For this model of the .300 AAC Blackout (aka 300 BLK), a Dremel tool was used to create a pie cut within the bullet and brass case. A measured amount of power, roughly 65% of spec charge, was placed inside the case with super glue. This cartridge was originally optimized for subsonic use with a suppressor, so the amount of powder used is small relative to the nominal case capacity. That leaves more room for the relatively large .30-caliber bullet.

sliced cutaway ammo ammunition FOG diagram

Last but definitely not least is the .50 Caliber BMG round (aka .50 Browning Machine Gun). Famed for its wartime use in the M2 Machine gun, the .50 BMG round is also used in civilian Long Range competitions. A typical .50 BMG cartridge holds over 225 grains of powder. That’s almost ten times the amount in a 5.56×45 NATO Round! To demonstrate the size of the .50 BMG, check out that .223 Rem for comparison.

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March 9th, 2024

Triangle Patches Offer Barrel Cleaning Benefits

Rigel BoreSmith Brush Patch Jag Pyramid Triangle patches

Product innovation is all about “building a better mousetrap”, or in this case, building a better bore-cleaning patch. A real smart guy, Shane Smith, has invented a triangular patch that earned a patent. The U.S. Patent Office has awarded a utility patent for BoreSmith’s Triangle Patch™. This unique cleaning patch was designed by Shane Smith, a mathematician/physicist who employed his scientific and firearms knowledge to create innovative bore-cleaning products.

Rigel BoreSmith Brush Patch Jag Pyramid Triangle patchesBoreSmith’s clever Triangle Patch™ (aka Pyramid Patch) presents more cleaning surface area to the bore wall than does a conventional square or round patch (of equivalent size). At the same time, the unique geometry makes Triangle Patches much less likely to jam in the barrel. This is because the notches in the sides of the triangle allow the patch to sit more uniformly on the jag (without bunching up). In addition, the Pyramid patch is must less likely to jam due to pleating. One reason conventional patches get stuck is unwanted 5-layer pleating. The special notches in the Pyramid patch remove all or most 5-layer pleating. As a result the patch does not bunch up and this also reduces rod bowing. SEE Triangle Patches HERE on Amazon.

The Triangle patch can be used with a standard jag but works best when paired with BoreSmith’s patented dual-diameter JagBrush. There are FOUR patch sizes: 17-20 Caliber, 22-27 Caliber, 27-35 Caliber, and 35-58 Caliber.

» Combo Kits with Triangle Patches and Dual-Diameter Brushes

Triangle Patch Function and Geometry Explained (See 1:18 time-mark):

NOTE: Despite what you may see in this video, you should ALWAYS insert brushes and patches from the chamber end first, using a fitted cleaning rod bore guide. With bolt-action rifles, NEVER insert a cleaning rod (with brush or jag) in through the muzzle. This may damage the delicate crown of your barrel.

The Triangle Patches work great with Boresmith’s patented dual-diameter bore brushes:

Triangle triangular patches boresmith
Triangle triangular patches boresmith
Triangle triangular patches combo kit boresmith

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March 9th, 2024

How Loud Noise Levels Cause Hearing Loss — Wear Protection

hearing protection sound noise american suppressor association ear muffs earplugs can silencer

Protect Your Hearing — Wear Protection Whenever You Shoot

hearing protection sound noise american suppressor association ear muffs earplugs can silencerNoise-induced hearing loss and tinnitus are two of the most common afflictions for recreational shooters and hunters. Everyone knows that gunfire is loud, but very few people understand the repercussions that shooting can have on their hearing until it’s too late.

The better quality suppressors can reduce the noise of a gunshot by 20 to 35 decibels (dB). Good muffs or plugs will reduce sound by 23 to 33 dB. By decreasing the overall sound signature, suppressors help to preserve the hearing of recreational shooters and hunters. Even the most effective suppressors, on the smallest and quietest calibers (.22 LR) reduce the peak sound level of a gunshot to between 110 to 120 dB. To put that in perspective, according to the National Institute for Occupational Safety and Health (NIOSH), that is as loud as a jackhammer (110 dB) or an ambulance siren (120 dB). For normal caliber handguns and rifles, suppressed sound levels routinely exceed 130 dB, just shy of OSHA’s “hearing safe” threshold of 140 dB.

hearing protection sound noise american suppressor association ear muffs earplugs can silencer

According to Dr. William W. Clark, the current Director of the Washington Univ. School of Medicine’s Audiology/Communication Sciences Program, a “serious threat to hearing comes from recreational hunting or target shooting”. This is in large part due to the fact that many people choose not to use traditional hearing protection devices like earplugs and earmuffs because they want to be able to hear their surroundings. Multiple studies have found that between 70 to 80% of hunters never wear earplugs or earmuffs, and nearly half of all target shooters don’t consistently wear traditional hearing protection. Thus, it should come as no surprise that for every five years of hunting, hunters become seven percent more likely to experience high frequency hearing loss.

This article is based on information from the American Suppressor Association (ASA). Since the ASA’s formation in 2011, three additional states have legalized suppressor ownership and 18 states have legalized suppressor hunting. For more information, visit www.AmericanSuppressorAssociation.com.

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March 4th, 2024

Choosing a Handgun — Smart Tips for Pistol Purchasers

Winchester Blog Becky Yackley pistol purchase handgun training

Are you in the market for your first handgun, for target use or for self-defense? The Winchester Blog has a good article for handgun buyers. This story, “Things You Should Know When Purchasing Your First Pistol”, provides many smart tips that can help you choose the right handgun, and save money in the process. In addition, the article explains how to train with your new pistol and handle it safely. READ Full Article.

If possible, you should test a variety of different pistols, to determine which works best for you. Check the feel, the ergonomics, the sight picture, and the controls. And, if possible, test the pistols with live-fire at a range which rents samples.

How do you know if your choice is right for you?
Once you’ve narrowed down choices, try to get time shooting the pistol(s) you are considering. You can usually rent guns at commercial ranges. This is an excellent way to “try before you buy.” NSSF has a list of places to shoot[.] When looking for a range that rents firearms, an online search and then a phone call to confirm what options are available is a solid plan. If you have friends and family who own a model you are interested in, ask if they will go to the range with you so that you can try it.

Take pistols for a test drive
First, dry-fire and manipulate the pistol. Can you easily lock the slide open? Are the sights suited to your vision? Then, fire a magazine or two of ammo [in a supervised range facility]. — Winchester Blog

The Winchester Blog article lists techniques that can help you get the “feel” for a particular firearm:

1. Practice the 4 Rules of Firearm Safety and make sure the gun is empty.

2. [After confirming the gun is empty] manipulate the slide, safety, magazine release, and dry-fire.

3. Perform a dry or empty magazine change — make sure you can hit the release and also reload a new magazine easily.

4. Perform a draw, or if you’re at a range where that is not allowed, simply pick the pistol up off the table and bring it up to your eye level and align the sights. Do this a few times. Can you acquire the sights quickly?

5. How does the backstrap fit your hand? Can you get both hands on the gun with enough “purchase” that you can really grip it well?

READ Full Winchester Blog Pistol Purchase Article »

This Winchester Blog article is by Becky Yackley. Becky has competed in 3-Gun, Bianchi pistol, Service Rifle, NCAA air rifle, smallbore and air pistol events around the world since 1989.

Smith wesson model 617 .22 LR revolver 22LR

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March 1st, 2024

Good Guide to Take-Down and Maintenance of AR Bolts

AR15 Bolt Disassembly

Accurate, modular, and supremely versatile, the AR15 is America’s favorite semi-auto rifle. But let’s face it, the AR is a maintenance hog. The AR’s gas tube blows carbon and soot right into the middle of the bolt assembly where it cakes on to the metal. The AR bolt also has many tiny parts, and small recesses, which must be cleaned regularly. This author has seen numerous ARs fail simply because there was gunk (dried lube, carbon, brass shavings) in the ejector slot or extractor spring recess.

A Clean AR is a Happy AR — Whether You Run ‘Wet’ or ‘Dry’
There are various schools of thought when it comes to maintaining an AR. Some folks prefer to run their AR “dry” with minimal lube on the lugs and friction surfaces. Other shooters prefer to run their ARs “wet”, with lots of lube. But whatever your preference, you need to clean your AR regularly. And nothing is more important than the AR’s bolt/carrier assembly. Because it is involved in feeding, firing, and extracting, the AR-15 bolt/carrier assembly can be considered the most critical portion of the AR-15 from a maintenance standpoint.

Bolt Take-Down Guide on Top Quark Blog
The editor of the Top Quark Blog has created an excellent illustrated AR15 Bolt Take-Down Guide that shows how to disassemble an AR15 bolt and carrier for regular cleaning. Even if you’re an experienced AR15 shooter, you can learn something from this page (sample at right), and you may want to bookmark it for future reference. The photos are large and clear and there are helpful hints for each step of the process.

The author knows his stuff and offers some important insights. For example, he notes that “Extractor springs in most AR15 bolt assemblies are fairly weak, and this can lead to various extraction-related failures. One of the few high points about Colt assemblies is their usage of higher-strength extractor springs. You can tell the difference by looking at the inner plastic insert. ‘Normal’ springs feature a blue plastic insert, Colt strong springs have a black insert.”

There is one notable oversight on this page — the author doesn’t cover disassembly and cleaning of the ejector assembly. This is actually quite important. A few small brass shavings, combined with carbon and lube in the ejector slot, WILL cause malfunctions. In fact, when this editor is called to diagnose problem ARs, the first things I look at (after swapping magazines) are the ejector recess and the slot for the extractor. Clogged ejectors are responsible for fail-to-ejects and other jams. It is essential that you keep the ejector hole clean. Old, gooey lube residues mixed with carbon and tiny brass shavings in the ejector recess will create all sorts of problems. As shown in the diagram below, it is simple to remove the ejector (#6) and ejector spring (#5), by drifting the ejector retaining pin (#4).

AR15 Bolt Assembly Diagram


NOTE: The original Quark Blog Article appears to be offline (See Quark LINK.) However, this excellent article has been preserved via the WayBack Machine Internet Archives. CLICK HERE to access the Full Quark Blog Article via WayBack Machine Archive.

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February 28th, 2024

Tumbler on Fire — Watch Out for Reloading Room Fire Risks

Electrical Fire Tumbler ExtinguisherA fire in the home is always to be feared. And a fire in your reloading room can be disastrous. Near your reloading bench you probably have flammable solvents, and maybe gunpowder. What would happen if an electrical fire started in your reloading room? Would you be alerted? Do you have a proper fire extinguisher at hand?

Here’s a true story from Forum Member Joe O. (aka “Joecob”) that provides a valuable safety lesson. After Joe started up his old tumbler, an internal connector worked loose, causing an arc which started a fire in his basement reloading area. Luckily Joe had a functioning smoke detector, and a fire extinguisher.

Very few of us would worry about fire when we plug in a tumbler or other AC-powered reloading tool. But there is always the possibility of a malfunction and a fire. Quick thinking (and a handy extinguisher) prevented serious damage to Joe’s reloading room and house — but things could have been worse (much worse), had Joe not responded quickly.

Fire in the Reloading RoomReport by Joecob
The day before ‘Sandy’ hit I was cleaning brass the way I always have. I set the vibratory tumbler on the back of my reloading bench in the basement. I loaded the media hopper with 40 fired empty brass cases (and walnut media), plugged the cord in, turned the tumbler on and went back upstairs to watch TV. I could hear the tumbler running in the background.

About half an hour later I heard the basement smoke alarm go off. I ran downstairs. Flames were licking from the melting plastic of the tumbler.

ABC fire extinguisherI grabbed the nearby ABC cannister extinguisher and squirted out the fire and soaked the charred bench areas with water. Good thing I had the extinguisher! And I was glad I religiously store powder and primers properly — away from the bench (and everything else).

What caused the fire? It looks like an internal AC connector finally vibrated loose enough to arc and ignite the plastic. WHEH! I had been using that thing for 25 years the same way without mishap. Guess I should have known to periodically check the guts of a thing that plugs in and vibrates for a living?

Today I went out and bought a new even bigger ‘Pro’ ABC extinguisher, plus a dual-detector smoke alarm, and an ultrasonic cleaner. That experience was scarier than the storm. I hope this true account might help someone else to avoid a bad experience.

Electrical Fire Tumbler ExtinguisherIn his account, Joe refers to an “ABC” cannister fire extinguisher. The “ABC” refers to the fire classification rating: Class A (trash, wood, and paper), Class B (liquids and gases), and Class C (energized electrical equipment) fires. There are many brands of ABC-rated extinguishers.

The rechargeable Kidde Pro 210 Fire Extinguisher (SKU 21005779) contains four pounds of a multipurpose monoammonium phosphate dry chemical extinguishing agent. It has a discharge time of 13 to 15 seconds, a discharge range of 10 to 15 feet, and an operating pressure of 100 PSI. The seamless aluminum cylinder measures 4.5 inches in diameter and 15.7 inches tall. The Kidde 210 has a 6-year limited warranty. This is now $45.40 on Amazon, 29% off the regular price.

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February 27th, 2024

Improve Trigger Technique for Better Accuracy & Higher Scores

trigger show bix'n andy otm tactical

Do you occasionally get completely unexplained flyers, or have a shot land straight down at 6 O’Clock, right below your point of aim? That could be caused by poor or inconsistent trigger technique. How you pull the trigger can and does affect your accuracy.

Many gun enthusiasts start with pistols. When they later start shooting rifles they may carry over some not-so-good practices acquired from shooting handguns with heavy 4 to 6-pound trigger pulls. You may want to “re-learn” your trigger techniques to get better rifle results.

Shooting Sports USA has a good article on trigger technique that offers many useful tips. That article also has many helpful illustrations, including the one shown above. Another illustration shows different types of trigger shoes (straight vs. curved) and explains how each makes a difference: “With a lightly curved trigger, the shooter’s finger can contact the trigger either high or low according to preference. Higher contact will increase the resistance.” READ ARTICLE HERE.

The article analyzes common errors, such as pulling the trigger with the very tip of the finger rather than the pad of the index finger: “Using the tip of the finger can lead to lateral pressure on the trigger, which throws off the shot.”

The article also explains that you should check your trigger regularly to make sure it is functioning properly and is not out of adjustment: “Just like any other moving part, the trigger can suffer from wear. In such a precise mechanism, tiny amounts of wear can cause major problems.”

Gary Eliseo tubegun prone rifle
The ergonomics of the Eliseo Tubegun allow a nice, straight trigger pull.

Trigger Tips

Six Suggestions for Making your Trigger Control More Consistent.

1. If your triggers are adjustable, set the pull weight appropriate to the discipline. For a hunting rifle, you don’t want an ultra-light trigger pull. For High Power, you may want a two-stage pull, while on a Benchrest rifle you may prefer a very light trigger.

2. If you have a two-stage trigger, experiment with different combinations of First Stage and Second Stage.

3. Have a friend watch you as you pull the trigger, and maybe even take a close-up video as you pull the trigger. This can reveal a variety of flaws.

4. Practice dry-firing to see if flaws in trigger technique are causing gun movement.

5. As an experiment, try pulling the trigger with your middle finger. Ergonomically, the middle finger has a more straight alignment with the tendons in your hand. This exercise can help you identify alignment issues with your index finger.

6. For stocks with adjustable Length of Pull you may want to set the LOP differently for bench shooting vs. prone or F-Class shooting.

trigger show bix'n andy otm tactical

trigger show bix'n andy otm tactical

When Only the Best Will Do…
German-made Bix’N Andy triggers, available from BulletCentral.com, are among the very best you can buy. Available in both single-stage and two-stage, Bix’N Andy triggers are extremely precise, repeatable and smooth. The unique internal, friction-reducing roller ball system allows for extremely low reset force, yielding an ultra-crisp let-off. Bix’N Andy triggers can be fitted with a variety of trigger shoes according to shooter preference.

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February 26th, 2024

Are Your Bullets Spinning Fast Enough? Use Twist Rate Calculator

Berger twist rate calculator

Berger twist rate calculatorBerger Twist-Rate Stability Calculator
On the Berger Bullets website you’ll find a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This cool tool tells you if your chosen bullet will really stabilize in your barrel.


CLICK HERE to Go to TWIST RATE CALCULATOR PAGE »

How to Use Berger’s Twist Rate Calculator
Using the Twist Rate Calculator is simple. Just enter the bullet DIAMETER (e.g. .264), bullet WEIGHT (in grains), and bullet overall LENGTH (in inches). On its website, Berger conveniently provides this info for all its bullet types. For other brands, we suggest you weigh three examples of your chosen bullet, and also measure the length on three samples. Then use the average weight and length of the three. To calculate bullet stability, simply enter your bullet data (along with observed Muzzle Velocity, outside Temperature, and Altitude) and click “Calculate SG”. Try different twist rate numbers (and recalculate) until you get an SG value of 1.4 (or higher).

Gyroscopic Stability (SG) and Twist Rate
Berger’s Twist Rate Calculator provides a predicted stability value called “SG” (for “Gyroscopic Stability”). This indicates the Gyroscopic Stability applied to the bullet by spin. This number is derived from the basic equation: SG = (rigidity of the spinning mass)/(overturning aerodynamic torque).

Berger twist rate calculator

If you have an SG under 1.0, your bullet is predicted not to stabilize. If you have between 1.0 and 1.1 SG, your bullet may or may not stabilize. If you have an SG greater than 1.1, your bullet should stabilize under optimal conditions, but stabilization might not be adequate when temperature, altitude, or other variables are less-than-optimal. That’s why Berger normally recommends at least 1.5 SG to get out of the “Marginal Stability” zone.

In his book Applied Ballistics For Long-Range Shooting, 3rd Ed., Bryan Litz (Berger Ballistician) recommends at least a 1.4 SG rating when selecting a barrel twist for a particular bullet. This gives you a safety margin for shooting under various conditions, such as higher or lower altitudes or temperatures.

Story idea from EdLongrange. We welcome reader submissions.
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February 26th, 2024

Cut-Away View Reveals Complex Interior of Modern Riflescope

Based on its external appearance, a modern riflescope may seem simple. It’s just a tube with two or three knobs on the outside right? Well, looks can be deceiving. Modern variable focal-length optics are complex systems with lots of internal parts. Modern scopes, even ‘budget’ optics, use multiple lens elements to allow variable magnification levels and parallax adjustment.

A few seasons back, we had a chance to look inside a riflescope thanks to a product display from ATK, now called Vista Outdoor, parent of Alliant Powder, CCI, Federal, RCBS, Speer, Weaver Optics. The Weaver engineers sliced open a Weaver Super Slam scope so you can see the internal lens elements plus the elevation and windage controls. We thought readers would like to see the “inner workings” of a typical modern rifle scope, so we snapped some pictures. The sectioned Super Slam scope was mounted inside a Plexiglas case, making it a bit hard to get super-sharp images, but you can still see the multiple lenses and the complex windage and elevation controls.

Check out the details of the focusing and magnification rings near the ocular (eyeball) end of the scope. There is very fine machining and threading to make everything work properly. The ocular lens is the piece of glass that faces the shooter while he aims.

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February 25th, 2024

Amazing Video — Bullet Impacts at 1 Million Frames Per Second

werner mehl kurzzeit.com high speed slow motion bullet video

Want to see a bullet hit a target in ultra-slow motion? Watch this video to witness some amazing things — such as a bullet jacket peeling back like a banana-skin (at time-mark 7:30). A while back, Werner Mehl of Kurzzeit.com produced a 10-minute video for the SHOT Show. This video has has been watched over 10.6 million times, making it one of the most popular shooting-related videos in history. Employing cameras recording at up to 1,000,000 (one million) frames per second, Mehl’s bullet flight video has been called “astounding” and “mesmerizing”. If you haven’t seen it yet, sit back and enjoy!

Watch This Video! It’s Really Something Special…

LINK: Kurzzeit.com Video System and PVM-21 Chronograph
Click the link above to learn more about Werner Mehl and his super-sophisticated camera systems that can record at 1,000,000 frames per second. On the same linked page you can learn about the advanced PVM-21 chronograph (now sold as the BMC-19) designed by Werner. Operating “all-infrared, all the time”, the PVM-21/BMC-19 is the best optical chronograph we have tested for very low light conditions, or very tricky light conditions.

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