Berger 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.
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).
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.
September 28, 2024 is National Hunting & Fishing Day. The annual celebration takes place on the the fourth Saturday of September every year. National, regional, state and local organizations will run thousands of “open house” hunting- and fishing-related events around the country. Events will include Fishing Derbys, Hunting Expos, Wing-shooting tournaments, and much more.
Hunting Safety Checklist
A good hunt begins with preparation. And during the hunt, safety is a key priority. To help hunters, the National Shooting Sports Foundation (NSSF) has created a Safety Checklist for hunters. This Hunting Safety Checklist, produced as part of the NSSF’s “Hunt S.A.F.E.” campaign, helps hunters follow good, safe practices in the field and at home.
409,000,000 views! Today’s five feature videos have, collectively, been viewed 372 million times on YouTube. Today’s Saturday special features five remarkable animated firearms videos from Matt Rittman, a very talented computer graphic artist. Matt employs multiple software programs to create these incredibly detailed animations. His software tools of the trade include Cinema 4D, Substance Painter, and Corona renderer. Don’t think this is easy. Some of these videos took over 500 man-hours to create. Enjoy!
AR-15 Full Animation — Components and Function
While there are other AR-15 animations on YouTube, we think this is the most accurate and creative, showing the function of a wide variety of components, including the bolt carrier, extractor, trigger, stock buffer, safety system, forward assist, and mag release. It also shows modes of a military M16, showing 3-round burst fire, and full-auto, employing disconnectors and auto sear. If you are planning to assemble/disassemble an AR, this is definitely worth watching start to finish. This video has recorded over 2 million views in just three weeks!
4:00 Auto Fire
4:58 Burst Fire
6:22 Bolt Catch
6:40 Sights
7:33 Adjustable Stock
7:50 Ejection Port Cover
Mauser Kar-98K Bolt Action Rifle video
This elaborate 3D animation shows how a Mauser-type Karabiner 98 Kurz (aka Kar-98K) bolt-action rifle works. Substance Painter was used to create the wood stock texture. Creator Matt Rittman states that this 3.7 minute video took over 500 man-hours to create. You have to admire the dedication involved in that kind of hard work.
This 3D animation video shows the popular Glock 19 (Gen 4) pistol. This modern, polymer-framed, striker-fired pistol has constant trigger pull for all shots. Some folks call this a DAO (double-action-only) trigger but that’s not really correct. Unlike the Model 1911, on a Glock there is no external safety on the frame or slide. The trigger “shoe” (the part that contacts finger) includes a central blade. This prevents the gun from firing unless the trigger is depresses normally. Glock calls this the “safe action”. The creator, Matt Rittman states: “Cinema 4D was used to create each individual part, as well as animating everything. Substance Painter was used to create the main textures. Corona renderer was used to render everything. This animation [with 84.6 million views] took me over 500 hours to create.”
Elements of Video:
0:11 Basic Function
0:39 Case Extraction
0:47 Cartridge Loading
1:02 Trigger Reset
1:28 Trigger Safety
Pump shotguns are essential firearms for hunting and home defense. The clever design of pump-action shotguns make them reliable even when feeding large diameter, blunt-ended 12 gauge shot-shells.
With 233 million views, this AK-47 video might just be the most-watched firearms tech video on YouTube. The video highlights the design features the account for the AK’s legendary reliability. For viewers with an eye to detail Matt adds this clarification: “The firing pin does NOT puncture the bullet primer. It just strikes it against the anvil, initiating the firing sequence.”
Are you feeling lucky? Here is one of the better hunting season prize packages we’ve seen in recent years. It’s easy enough to enter to win an impressive collection of products including a SIG Sauer P320 pistol, multiple Vortex optics products, pack system, boots and much more. There is no purchase necessary for a chance to win.
Alien Gear Holsters, American manufacturer of holsters and firearms accessories, has pulled together some of the top brands in the industry to create an impressive Hunting Season Giveaway for 2022. There’s a massive collection of cool products for the 2022 Hunting Season Prize Package. Shawn Hostetter, CEO of Alien Gear Holsters, states: “All together this prize package is worth several thousand dollars and would make an incredible start to hunting season, or a fantastic gift for the hunter in the family.”
Products Included in the impressive Prize Package:
- SIG Sauer P320 XTen 10mm Pistol
– VORTEX Optics: Diamondback HD 20-60×85 Spotting Scope, Diamondback HD 10×50 Binoculars and Defender-ST Red Dot sight
– IA3K Pack System from Initial Ascent
– Select Hunting/trekking Boot from Crispi
– MOB GameBags and Carbon X Tracking Poles from Argali Outdoors
– Zeus Air and First Aid Plus Kit from Uncharted Supply Co.
– One-year subscription to an OnX Elite Membership
– 30mm Medium Rifle Rings and goodies from Seekins Precision
– New Select Holster from Alien Gear Holsters
It’s easy to enter by filling out Online Entry Form. Eligible participants have until September 30, 2024, to enter for a random chance to win this ultimate hunting package.
The Pew Pew Tactical website has interesting article on rifle and pistol cartridges and bullet types. This contains a large selection of interesting photographs and illustrations. If you load and/or shoot for a wide variety of cartridge types, you’ll find that article well worth reading. It has nearly 50 photographs and more than a dozen short videos. READ FULL Article.
The article shows all types of pistol bullets, along with a variety of rifle projectiles. It even illustrates multiple types of shotshell cartridges.
The article also explains the basic components of modern cartridges –bullet, case, powder, and primer:
Photo courtesy Ammunitiontogo.com which sells ammo from many leading brands.
Popular Cartridge Types Profiled
The article provides quick summaries of popular ammunition types including 9mm Luger (9x19mm), .357 Magnum, .40 SW, .45 ACP, .223 Rem, and .308 Winchester. The author’s favorite pistol round is the 9mm Luger: “9mm is my personal favorite and if there was a “Goldilocks” round, this would be it. The very first gun I bought was a 9mm. They’re fun at the range. They’re good for defense. It is the standard round for NATO countries and the majority of police forces around the world. It is mild shooting, can vary in weight from 115 to 147 grains, and has varying stopping power based on the type of bullet.”
This Pew-Pew Tactical guide to cartridge types also provides a quick explanation of cartridge ignition — both centerfire and rimfire: “The rimfire’s primer is built into the rim while the centerfire cartridge has the primer in the center. Pro tip — if you can see a circle in the middle…it’s a centerfire cartridge.”
There are two common types of centerfire primers — Boxer and Berdan. This helpful Wikipedia illustration shows how Boxer, Berdan, and rimfire primers ignite the powder in the cartridge:
This centerfire and rimfire ignition animation is by BBODO – Own work, CC BY-SA 3.0 licensed under the Creative Commons Attribution-Share Alike 3.0 license.
This new ultra-compact spotting scope that should prove useful for hunters and PRS/NRL competitors. The Vortex Viper HD 11-33x50mm spotting scope weighs just 27 ounces — great for back-country hunting where light weight and portability is crucial. This spotter is offered in both straight and angled models for $599.99. It employs a handy dual-focus system, allowing a rapid initial focus plus precision final focus.
The compact Viper HD 11-33×50 has an HD Optical System encased in rugged outer body with rubberized armor. About the size of a large water bottle, this compact, 27 oz. spotter stows easily in a pack. It features a removable eyepiece and has an ARCA mount for tripods.
- Compact and Lightweight maximizes portability for long treks
– Dual-Focus enables rapid and precise image focusing
– ARCA-Swiss Compatible enables quick, versatile, and secure mounting options
– Removable Eyepiece enhances packability, ideal for backcountry hunts
– Twist-up Eyecup provides customized eye relief
– Rubber Armor ensures durability, protection, and a non-slip grip
For a detailed list of technical specifications, frequently asked questions, and high-resolution images, check out the Viper® HD 11-33x50mm Spotter on the Vortex New Product Portal.
Hunting season is coming soon. It’s time to sight-in those deer rifles, check the optics, and make sure you’re ready to go. We know some hunters might enjoy shooting game profile targets when at the range for the sight-in process. To that end, here are six animal profile targets from Gun.Deals. Right-click any target to download the printable PDF file, designed to print to standard 8.5″ x 11″ paper. All these targets include entry boxes for Shooter Name, Score, Range (distance), and Date.
Deer Targets with Center Hit Zones Gun.Deals offers two different deer targets, both free to download. We prefer the standing buck with target ring in center mass (left below). Hit the red “10” for maximum points. You can also use this target for rimfire fun practice. NOTE: The ideal shot location for a deer or elk is in a different location, closer to the heart location in the lower, forward torso. However, these targets can be used for initial practice. CLICK HERE for specific anatomical targets for various game species.
Bear Targets with Center Bulls
Few of us have actually encountered large bears in the wild. But if you do… it can be scary. Work on your bear recognition skills with these two targets, a standing bear, and a bear horizontal profile.
Sight-In Target and Bullseye Target
Courtesy of Gun.Deals, we’ve also included a conventional bullseye and a sight-in target. You can augment that sight-in sheet with neon orange Birchwood-Casey Target Spots if you want multiple aim points. A target pack with 160 1.5″ Target Dots is just $3.33 at Amazon.
In a helpful NSSF video, Ryan Cleckner explains why you normally should avoid canting your rifle — rotating it clockwise or counter-clockwise. Cleckner explains that canting the rifle in one direction or another will change the point of impact: “When you rotate the rifle, not only does the [POI move] in the direction that you’re rotated, [but] it also loses some of its elevation as it rolls down.” This, Cleckner explains, can make you miss on one side or the other:
Cant to the Left — You’re going to miss low and left.
Cant to the Right — You’re going to miss low and right.
In this video, starting at the one-minute mark, Cleckner shows the effect of rifle canting when engaging a 600-yard target. A few degrees of cant (either to the left or to the right), moves the shot POI completely off the steel silhouette target. The POI change occurs mainly because you are lowering (and laterally shifting) the scope sight-line relative to the bore axis, effectively changing your zero.
David Tubb has explained: “Every 1 degree you are off on a cant, is about six inches of difference laterally at 1000 yards”.
Position Shooting with Sling — Rifle Cant Considerations
Cleckner’s discussion assumes that the scope or sights are set to hit center with the rifle level and plumb. That works for most situations when shooting prone off bipod, front mechanical rest, or front sandbag. However, many sling shooters, including David Tubb and John Whidden, do tilt or cant their rifles slightly inward because this allows a more comfortable hold with sling, or allows better eye-to-sight alignment. Holding the rifle at an angle can work — but the angle of cant must be consistent for every shot. Canting the rifle is not a sin by itself. However, after you confirm your zero on your target, the degree of cant must be the same for EVERY shot. You must maintain that exact same degree of rotation on each shot or you will experience the shot POI movement Cleckner illustrates. Consistency is the key.
John Whidden, 5-time Nat’l Long Range Champion, holds a Palma rifle. John now shoots a match rifle with an Anschutz stock which he holds more upright, but still with some counter-clockwise cant. John also installed his iron sights at an angle so that the adjustments are correct (and plumb) even with his canted hold: “While it may not be obvious in the picture, the sights on my rifle are set up so that they’re straight vertical and horizontal while I hold the rifle canted. Making sure your adjustments (scope or sights) are vertical and horizontal is a critical piece of the pie.”
Inexpensive Dual-Diameter Scope-Mounted Bubble Level
The best way to avoid inconsistent rifle canting is to use a bubble level fitted to rail or scope. One very affordable and versatile product is the Jialitte Scope Bubble Level. This features a 30mm milled inside diameter, plus an inner insert ring so it will also fit 1″-diameter main tubes. The Jialitte unit is nicely radiused, and has a low profile in the middle. User reviews have been very positive. You could easily pay $35.00 or more for a 30mm scope level. This costs just $9.99 on Amazon.
Many hunters and precision rifle competitors use muzzle brakes because these ported devices reduce felt recoil significantly. That makes a real difference getting back on target for quick follow-up shots. While many rifle owners appreciate the benefits of muzzle brakes, they may also neglect their brakes, allowing hard carbon and powder residue to build up. Not good. You should regularly clean your muzzle brake to remove fouling and carbon build-up.
As Mark Edgreen posted: “Carbon build up on the crown and in the brake is a recipe for poor accuracy.” And another gunsmith reported that customers complained about guns that “shot out way too early” but they only needed to have the brakes cleaned.
Gunsmith and PRS/NRL competitor Jim See recently reminded his Facebook Fans about the importance of cleaning muzzle brakes: “How many times do I have to say it? You need to maintain your rifles. Clean your muzzle brakes people!”. Jim, who runs Elite Accuracy LLC, notes that hard carbon build-up in brakes can definitely harm accuracy. Look at this example:
Muzzle Brake Cleaning Methods
There are various methods for cleaning a brake, we list a variety of techniques, but we would start with NON-corrosive ultrasound. You’ll want to remove the muzzle device before doing these tasks.
1. Use Ultrasonic Cleaning Machine with cleaning solution. This may be the most efficient method: “I place my brake in the ultrasonic cleaner. Shiney as new.” (Jim Moseley).
2. Spray with commercial Carb Cleaner and brush. Then apply anti-corrosion coating.
3. Soak in half hydrogen peroxide and half vinegar. Suggestion: “Let sit over night and carbon melts off. Brush remaining carbon off, rinse and put the brake back on.” Apply anti-corrosive before mounting.
4. Soak in 50/50 solution of water and white vinegar and brush. (Be sure to apply anti-corrosion coating, such as Eezox, after soaking).
5. Tumble in liquid solution with stainless pins. Comment: “Comes out slightly faded, but perfectly clean on stainless, non-painted brakes though.” Warning — do NOT do this with threaded brakes — tumbling could affect threads of screw-on brakes. Also, tumbling can harm painted or Cerakote finishes.
Gunsmithing Tip: By fitting the muzzle brake so that the barrel crown is slightly forward, it is easier to wipe carbon fouling off the end of the barrel. See photo:
Our friend Gavin Gear has just released an excellent video showing how to make a threaded Modified Case for use with the Hornady Lock-N-Load Overall Length Gauge. You can watch Gavin make a Modified Case start to finish in the video below:
Video Shows How to Drill and Tap Modified Case
Gavin has some clever tricks. First he uses a sizing die to hold the cartridge case during the threading process. Second he uses two drill bits in sequence — a smaller bit to ream out the primer pocket, and then a larger “M” bit to increase the hole diameter before threading the brass. Finally he leaves the threading tap IN the brass, locks the tailstock, and then “gently pulls on the quill” to remove the brass from the die held in his lathe (See 5:46 timemark).
Get the Correct 5/16″-36 RH Tap
Unfortunately, Hornady has selected an uncommon thread type for OAL Gauges. You probably won’t be able to buy the correct 5/16″ – 36 RH HSS Tap at your local hardware store. However you CAN order this special tap from Amazon for $9.99.
Modified Case Q & A — TECH TIPS
Why do I need a Modified Case?
Every serious reloader should have a Modified Case for each cartridge type they shoot. The reason is that this allows you to get very precise measurements of the length-to-lands in your chamber. When used with the Hornady OAL Gauge, with some practice, you should be able to get repeatable length-to-lands measurements within about 0.0015″. We generally do 4-5 measurements with the OAL Gauge and usually 3 or 4 will be “on the money”. NOTE: We recommend a gentle, easy pressure on the plastic pusher rod. Don’t push too hard or you will jam the bullet hard into the lands, which produces inconsistent results.
Can’t I Just Buy a Modified Case?
Hornady makes a variety of Modified Cases sold on Amazon and through retailers such as Midsouth. While Hornady makes modified cases for many standard cartridges, if you shoot a wildcat such as the 6mm Dasher or .284 Shehane, you’ll need to create a custom modified case. And even if you shoot a standard cartridge such as the .308 Win, you can get more consistent measurements with a custom Modified Case.
If you do decide to make your own modified case, you’ll want to start with a case that’s been fired in your rifle. That way you get the best fit to YOUR chamber. Also, you won’t need to expand the neck to provide bullet clearance. Then you need to drill out the primer pocket and tap the base of the case to match the threads on the Hornady OAL Gauge tool. Make at least two modified cases, as you’ll probably misplace one at some point.
MORE INFORMATION: Want to learn more? We published a much longer story in which Erik Cortina explains in greater detail how to made the Modified Case. That article illustrates the 5/16″ – 36 RH HSS Tap required and shows how to set up the lathe to drill and tap your case. If you are serious about making your own Modified Cases, you should Read the Full Article.
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.
Popular Cartridge Types Profiled
