Figure 1. When the bullet is seated farther out of the case, there is more volume available for powder. This enables the cartridge to generate higher muzzle velocity with the same pressure.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1 by Bryan Litz forBerger Bullets.
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. Cartridge Overall Length (COAL) is also a variable that can be used to fine-tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a magazine. In this article, we’ll explore the various effects of COAL, and what choices a shooter can make to maximize the effectiveness of their hand loads.
Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI)
Most loading manuals (including the Berger Manual), present loading data according to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) standards. SAAMI provides max pressure, COAL and many other specifications for commercial cartridges so that rifle makers, ammo makers, and hand loaders can standardize their products so they all work together. As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.
Bullet seating depth is an important variable in the accuracy equation. In many cases, the SAAMI-specified COAL is shorter than what a hand loader wants to load their rounds to for accuracy purposes. In the case where a hand loader seats the bullets longer than SAAMI specified COAL, there are some internal ballistic effects that take place which are important to understand.
Effects of Seating Depth / COAL on Pressure and Velocity
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long. In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short.
When you think about it, it makes good sense. After all, when you seat the bullet out longer and leave more internal case volume for powder, you’re effectively making the cartridge into a bigger cartridge by increasing the size of the combustion chamber. Figure 1 illustrates the extra volume that’s available for powder when the bullet is seated out long.
Before concluding that it’s a good idea to start seating your bullets longer than SAAMI spec length, there are a few things to consider.
Geometry of a Chamber Throat
The chamber in a rifle will have a certain throat length which will dictate how long a bullet can be loaded. The throat is the forward portion of the chamber that has no rifling. The portion of the bullet’s bearing surface that projects out of the case occupies the throat (see Figure 2).
The length of the throat determines how much of the bullet can stick out of the case. When a cartridge is chambered and the bullet encounters the beginning of the rifling, known as the lands, it’s met with hard resistance. This COAL marks the maximum length that a bullet can be seated. When a bullet is seated out to contact the lands, its initial forward motion during ignition is immediately resisted by an engraving force.
Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.
A very common practice in precision reloading is to establish the COAL for a bullet that’s seated to touch the lands. This is a reference length that the hand loader works from when searching for the optimal seating depth for precision. Many times, the best seating depth is with the bullet touching or very near the lands. However, in some rifles, the best seating depth might be 0.100″ or more off the lands. This is simply a variable the hand loader uses to tune the precision of a rifle.
Team Lapua’s Jack Neary delivered an impressive performance at the NBRSA Eastern Region Fall Finale, held October 4–5 at the historic Shelby County Deer Hunters Association Benchrest Range in Sidney, Ohio. The Shelby County range, which was established in 1843, is said to be the oldest gun club in the United States. Neary claimed first place in the 2-Gun Grand Aggregate, showcasing extreme consistency and with his benchrest rifle chambered in 6mm PPC.
The match featured manageable conditions at 100 yards on Saturday, followed by challenging winds at 200 yards on Sunday afternoon. Despite the shifting conditions, Neary excelled, also securing first place in the Light Varmint 100-yard class on Saturday morning.
“After a very promising day of practice on Friday, I was pleased with the consistent small groups my rifle produced during the entire weekend match,” said Neary. “Using Vihtavuori N133 powder, Lapua .220 Russian Cases, and custom-built bullets with Berger J4 Jackets, I as able to navigate a talented field of accomplished Benchrest shooters for the two-gun win.”
We congratulate Jack Neary for his outstanding performance and well-earned victory in the 2-Gun Grand Aggregate, demonstrating exceptional marksmanship and consistency throughout the weekend.
In discussions of ballistics, you’ll see references to “tangent”, “secant”, and “hybrid” bullet shapes. We know that, for many readers, these terms can be confusing. To add to the confusion, bullet makers don’t always identify their projectiles as secant or tangent designs. This article provides a basic explanation of tangent, secant, and hybrid ogive bullet designs, to help you understand the characteristics of these three basic bullet shapes.
Tangent vs. Secant vs. Hybrid
Most match bullets produced today use a tangent ogive profile, but the modern VLD-style bullets employ a secant profile. To further complicate matters, the latest generation of “Hybrid” projectiles from Berger Bullets feature a blended secant + tangent profile to combine the best qualities of both nose shapes. The secant section provides reduced drag, while the tangent section makes the bullet easier to tune, i.e. less sensitive to bullet seating depth position.
Berger Bullets ballistician Bryan Litz explains tangent and secant bullet ogive designs in a glossary section of his Applied Ballistics website, which we reprint below. Bryan then explains how tangent and secant profiles can be combined in a “hybrid” design.
How Bullet Ogive Curves are Defined
While the term “ogive” is often used to describe the particular point on the bullet where the curve reaches full bullet diameter, in fact the “ogive” properly refers to the entire curve of the bullet from the tip to the full-diameter straight section — the shank.
Understanding then, that the ogive is a curve, how is that curve described?
LITZ: The ogive of a bullet is usually characterized by the length of its radius. This radius is often given in calibers instead of inches. For example, an 8 ogive 6mm bullet has an ogive that is a segment of a circular arc with a radius of 8*.243 = 1.952”. A .30-caliber bullet with an 8 ogive will be proportionally the same as the 8 ogive 6mm bullet, but the actual radius will be 2.464” for the .30 caliber bullet.
For a given nose length, if an ogive is perfectly tangent, it will have a very specific radius. Any radius longer than that will cause the ogive to be secant. Secant ogives can range from very mild (short radius) to very aggressive (long radius). The drag of a secant ogive is minimized when its radius is twice as long as a tangent ogive radius. In other words, if a tangent ogive has an 8 caliber radius, then the longest practical secant ogive radius is 16 calibers long for a given nose length.”
Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths
Ogive Metrics and Rt/R Ratio
LITZ: There is a number that’s used to quantify how secant an ogive is. The metric is known as the Rt/R ratio and it’s the ratio of the tangent ogive radius to the actual ogive radius for a given bullet. In the above example, the 16 caliber ogive would have an Rt/R ratio of 0.5. The number 0.5 is therefore the lowest practical value for the Rt/R ratio, and represents the minimum drag ogive for a given length. An ogive that’s perfectly tangent will have an Rt/R ratio of 1.0. Most ogives are in between an Rt/R of 1.0 and 0.5. The dimensioned drawings at the end of my Applied Ballistics book provide the bullets ogive radius in calibers, as well as the Rt/R ratio. In short, the Rt/R ratio is simply a measure of how secant an ogive is. 1.0 is not secant at all, 0.5 is as secant as it gets.
Hybrid Bullet Design — Best of Both Worlds?
Bryan Litz has developed a number of modern “Hybrid” design bullets for Berger. The objective of Bryan’s design work has been to achieve a very low drag design that is also “not finicky”. Normal (non-hybrid) secant designs, such as the Berger 105gr VLD, deliver very impressive BC values, but the bullets can be sensitive to seating depth. Montana’s Tom Mousel has set world records with the Berger 105gr VLD in his 6mm Dasher, but he tells us “seating depth is critical to the best accuracy”. Tom says a mere .003″ seating depth change “makes a difference”. In an effort to produce more forgiving high-BC bullets, Bryan Litz developed the hybrid tangent/secant bullet shape.
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.
Guest Article By Michelle Gallagher, Berger Bullets
Let’s face it. In the world of firearms, there is something for everyone. Do you like to compete? Are you a hunter? Are you more of a shotgun shooter or rifle shooter? Do you enjoy running around between stages of a timed course, or does the thought of shooting one-hole groups appeal to you more? Even though many of us shoot several different firearms and disciplines, chances are very good that we all have a favorite. Are we spreading ourselves too thin by shooting different disciplines, or is it actually beneficial? I have found that participating in multiple disciplines can actually improve your performance. Every style of shooting is different; therefore, they each develop different skills that benefit each other.
How can cross-training in other disciplines help you? For example, I am most familiar with long-range prone shooting, so let’s start there. To be a successful long-range shooter, you must have a stable position, accurate ammunition, and good wind-reading skills. You can improve all of these areas through time and effort, but there are other ways to improve more efficiently. Spend some time practicing smallbore. Smallbore rifles and targets are much less forgiving when it comes to position and shot execution. Long-range targets are very large, so you can get away with accepting less than perfect shots. Shooting smallbore will make you focus more on shooting perfectly center shots every time. Another way to do this with your High Power rifle is to shoot on reduced targets at long ranges. This will also force you to accept nothing less than perfect. Shoot at an F-Class target with your iron sights. At 1000 yards, the X-Ring on a long range target is 10 inches; it is 5 inches on an F-Class target. Because of this, you will have to focus harder on sight alignment to hit a center shot. When you go back to the conventional target, you will be amazed at how large the ten ring looks.
Also, most prone rifles can be fitted with a bipod. Put a bipod and scope on your rifle, and shoot F-TR. Shooting with a scope and bipod eliminates position and eyesight factors, and will allow you to concentrate on learning how to more accurately read the wind. The smaller target will force you to be more aggressive on your wind calls. It will also help encourage you to use better loading techniques. Nothing is more frustrating than making a correct wind call on that tiny target, only to lose the point out the top or bottom due to inferior ammunition. If you put in the effort to shoot good scores on the F-Class target, you will be amazed how much easier the long-range target looks when you return to your sling and iron sights. By the same token, F-Class shooters sometimes prefer to shoot fast and chase the spotter. Shooting prone can help teach patience in choosing a wind condition to shoot in, and waiting for that condition to return if it changes.
Benchrest shooters are arguably among the most knowledgeable about reloading. If you want to learn better techniques about loading ammunition, you might want to spend some time at benchrest matches. You might not be in contention to win, but you will certainly learn a lot about reloading and gun handling. Shooting F-Open can also teach you these skills, as it is closely related to benchrest. Benchrest shooters may learn new wind-reading techniques by shooting mid- or long-range F-Class matches.
Position shooters can also improve their skills by shooting different disciplines. High Power Across-the-Course shooters benefit from shooting smallbore and air rifle. Again, these targets are very small, which will encourage competitors to be more critical of their shot placement. Hunters may benefit from shooting silhouette matches, which will give them practice when shooting standing with a scoped rifle. Tactical matches may also be good, as tactical matches involve improvising shots from various positions and distances. [Editor: Many tactical matches also involve hiking or moving from position to position — this can motivate a shooter to maintain a good level of general fitness.]
These are just a few ways that you can benefit from branching out into other shooting disciplines. Talk to the other shooters. There is a wealth of knowledge in every discipline, and the other shooters will be more than happy to share what they have learned. Try something new. You may be surprised what you get out of it. You will certainly learn new skills and improve the ones you already have. You might develop a deeper appreciation for the discipline you started off with, or you may just discover a new passion.
This article originally appeared in the Berger Blog. The Berger Blog contains the latest info on Berger products, along with informative articles on target shooting and hunting.
The 6mmBR Norma cartridge has spawned many great variants in multiple calibers: 6mm Dasher, 6BRA, 22 BR, 22 Dasher, 30 BR and others. This article is about a handsome 22 BR Rem-action varmint rig.
Richard Franklin (who operated Richard’s Custom Rifles prior to his retirement), has built scores of varmint rifles, in many different calibers. One of Richard’s all-time favorite varmint rifles is a 1:14″-twist, 22 BR built on his Model 11 stock in laminated Black Walnut and fiddleback maple. Richard says the rifle is versatile and deadly accurate out to 400 yards. Richard uses a Leupold 8.5-25x50mm LRT with varmint reticle.
Richard’s 22 BR Varmint Rifle with Lilja Barrel
Richard tells us: “[Shown above] is my light walking varminter. It’s built on a blue-printed Stainless Steel Remington 700 short action and chambered as a no-turn 22 BR for Lapua brass. The bolt handle is a Dave Kiff replacement and I’ve fitted a Jewel BR trigger with bottom safety. The barrel is a Lilja, 1:14″ #6 contour with a muzzle diameter of .750″. I shoot the 40gr V-Max bullets in the rifle at 4000 FPS. It’s tough on hogs if you don’t try them too far. 400 yards is about the max with it.
Accuracy is outstanding and with Roy, Mike, my grandson and myself shooting this rifle I don’t believe it has missed more than three hogs out of over 100 we shot at one summer. This rifle is carried in a ceiling rack in the truck where it’s handy and is used by the first person that grabs it when a hog is sighted if we are moving between setups. The Varmint reticle on the Leupold (shown below) is nice for quick hold-overs as you change distances.”
At right is a another Franklin Model 11 stock in Birdseye maple. That photo shows the details of the thumbhole stock.
Editor’s Note: We have shot a 1:8″-twist 22 BR in varmint matches and it was very accurate with 80gr bullets. It actually shot flatter out to 500 yards than our 6mmBR running 105-grainers. If we were to build a new long-range, bolt-action varmint rifle it would probably be a 22 BRA, essentially a 22 BR with 40° shoulder. That gives you a very stable cartridge with a bit more capacity. The 22 BRA retains a longer neck compared to the 22 Dasher, which is also an excellent cartridge — versatile and accurate.
22 BR Rivals 22-250 Performance
With bullets in the 40gr to 60gr weight range, the 22 BR gives up very little in velocity to a 22-250, despite burning quite a bit less powder (30-32 grains for the 22 BR vs. 35-38 grains for the 22-250). With a match-quality chamber, the 22 BR will probably have an edge in accuracy over a 22-250, and you should experience longer barrel life. Here are some recommended 22 BR loads for 40-60gr bullets:
Over the past 12 months, this article was one of the TOP 20 most-read Daily Bulletin features. We’re reprising it today for those who may have missed it the first time. The above diagram comes from a TiborasurasRex YouTube Video comparing G1 and G7 BC models. CLICK HERE to watch the video.
The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.
Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”
The simple answer is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.
G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.
Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, believes the G7 standard is preferrable for long-range, low-drag bullets: “Part of the reason there is so much ‘slop’ in advertised BCs is because they’re referenced to the G1 standard which is very speed sensitive. The G7 standard is more appropriate for long range bullets. Here’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:
G1 BCs, averaged between 1500 fps and 3000 fps:
Berger 180 VLD: 0.659 lb/in²
JLK 180: 0.645 lb/in²
The reason the BC for the JLK is less is mostly because the meplat was significantly larger on the particular lot that I tested (0.075″ vs 0.059″; see attached drawings).
For bullets like these, it’s much better to use the G7 standard. The following BCs are referenced to the G7 standard, and are constant for all speeds.
Many modern ballistics programs, including the free online JBM Ballistics Program, are able to use BCs referenced to G7 standards. When available, these BCs are more appropriate for long range bullets, according to Bryan.
[Editor’s NOTE: BCs are normally reported simply as an 0.XXX number. The lb/in² tag applies to all BCs, but is commonly left off for simplicity.]
This article is copyright 2023 AccurateShooter.com. No 3rd Party republication of this article is allowed without advance approval and payment of licensing fees.
Emil Praslick III is widely recognized as one of the greatest wind wizards on the planet — a master at identifying wind value and direction, and predicting wind cycles. As coach of the USAMU and top civilian teams, Emil has helped win many high-level championships. In the three videos we feature today, Emil, who works with Capstone Precision Group (Berger, Lapua, SK, Vihtavuori) and Team Applied Ballistics, explains how to determine wind direction and velocity using a variety of indicators. Praslick, now retired from the U.S. Army, was an 18-time National and 2-time World Champion coach with the USAMU.
Video ONE: Wind Theory Basics — Understanding “Wind Values”
In this video from UltimateReloader.com, Emil explains the basics of modern wind theory. To properly understand the effect of the wind you need to know both the velocity of the wind and its angle. The combination of those variables translates to the wind value. Emil also explains that the wind value may not be constant — it can cycle both in speed and velocity. Emil also explains some of the environmental conditions such as mirage that can reveal wind conditions.
Video TWO: Determining the Direction of the Wind
Key Point in Video — Find the Boil
Emil explains how to determine wind direction using optic. The method is to use spotting scope, riflescope, or binoculars to look for the “Boil” — the condition in mirage when the light waves rising straight up. The wind will generate that straight-up, vertical boil in your optics when it is blowing directly at you, or directly from your rear. To identify this, traverse your scope or optics until you see the boil running straight up. When you see that vertical boil, the direction your optic is pointing is aligned with the wind flow (either blowing towards you or from directly behind you).
Video THREE: The No Wind Zero Setting
In this second video, Emil defines the “No-Wind Zero”, and explains why competitive shooters must understand the no-wind zero and have their sights or optics set for a no-wind zero starting point before heading to a match. In order to hit your target, after determining wind speed and direction, says Emil, “you have to have your scope setting dialed to ‘no wind zero’ first.”
Coach of Champions — Emil Praslick III
SFC Emil Praslick III, (U.S. Army, retired) works with Berger Bullets and Applied Ballistics. Emil served as the Head Coach of the U.S. National Long Range Rifle Team and Head Coach of the USAMU for several years. Teams coached by Emil have won 33 Inter-Service Rifle Championships. On top of that, teams he coached set 18 National records and 2 World Records. Overall, in the role of coach, Praslick can be credited with the most team wins of any coach in U.S. Military history.
Today’s featured rifle comes from the land Down Under — Australia. This impressive .300 WSM F-Open rig has top-tier components/accessories from multiple countries. From the USA comes the Borden BRMXD action, Krieger barrel, McMillan Kestros ZR stock, and R.A.D. 2 recoil system. The 10-60x56mm March scope comes from Japan. The Lenzi rear bag is from Italy, and the SEB front rest is from Indonesia, with a Rodzilla top from America. This rifle proved very accurate from the get-go, winning its first match, emerging with the top 600m Aggregate. This .300 WSM F-Open beast is definitely a winner.
Impressive .300 WSM F-Open Rifle from Australia
This rifle belongs to Kris Wilson, aka “Willow” on our AccurateShooter Forum. Just last week Kris posted in the Pride and Joy Rifle thread: “Got my latest build up and running — a .300 WSM F-Open rifle. Never shot a .300 WSM (Winchester Short Magnum) before today and I have to say that, while the recoil is on the sharp side, it’s entirely manageable thanks to the stock design and front rest.” Kris resides in Sydney, New South Wales, Australia and shoots at the Hornsby RSL Rifle Club. He has been his club’s F-Open Champion, even with some very tough competition — his club boasts two Australian F-Open championship-winning club members. Kris loves the F-Class game: “I started rifle shooting in 2015 when I was introduced to the world of F-class through shopping for a riflescope. Once I saw what F-class was all about, I was hooked.”
Kris produced this video on December 5, 2020. He reports: “Here is my first real outing with my new .300 WSM. I had previously sighted in at 50 meters at an indoor range to establish a wind zero. Had a rough idea of velocity so I threw together two loads to run at 600 meters. Our Aussie targets have a max numerical ring value of 6 (equivalent to “10” on USA targets). On Stage One I shot a 60.8X (60.10X max possible), grouping about 3.7 inches. On Stage Two, shown in this video, I shot a a 66.9X (66.11X max possible) with a 3-inch grouping. I took first place in both stages and won the overall Aggregate for the day. That earned me a Christmas ham and turkey for my trouble!”
.300 WSM Rifle Hardware, Cartridge Choice, and Reloading
Report by Kris Wilson, NSW, Australia
Stock: McMillan Kestros ZR with R.A.D. 2 system. 70% black, 15% grey, 15% red.
Action: Borden Rimrock BRMXD, left bolt, right port, left eject. The action is fully DLC coated and fitted with a +20 MOA rail
Trigger: TriggerTech Diamond
Barrel: Krieger 1:10″-twist, 4 groove finished at 31″ and fitted with an Ezell tuner.
Scope: March High Master 10-60x56mm with MTR-1 reticle, illuminated
Rings: ARC M10 High Rings
Front Rest: SEB Mini Rest, with Rodzilla Rest Top system
Rest Feet: Bryan Blake (F-Class Products) adjustable stainless feet
Rear Support: Lenzi (Italy) LR Rear bag, with custom metal base plate
Cartridge Selection — Why the .300 WSM Was Chosen over a 7mm Cartridge
I set out with the goal of building my ultimate F-Open rifle. Now “ultimate” is of course subjective, but I did not want to leave any stone unturned when it came to building a .300 WSM. When researching the equipment for my new build I had a couple of ideas in mind. I was already shooting a 7mm, in the form of a 280AI which had served me well, but I already had plans to switch to a .284 Shehane with the introduction of Peterson .284 Win brass, coupled with the fact Norma stopped making 280AI brass (Note: Peterson now makes 280AI brass). While I was reasonably well-covered with my .284 Shehane, I wanted something with a bit more horsepower to hold up at long range in choppy conditions. A lot of the top guys here shoot 7mm SAUMs but I wasn’t keen on going down that path. Why? For every accurate SAUM I’ve seen, I’ve seen others struggle and given that the 7mm SAUM seems to be particularly hard on barrels, I wanted something that could match the 7mm SAUM ballistically, but have better barrel life.
After plenty of research on AccurateShooter.com, and speaking with some shooters, both locally and in the USA, I decided to give the .300 WSM a go. This cartridge is not particularly popular in Australia for F-Open, primarily because most states enforce muzzle energy restrictions, so pushing the .300 WSM to its potential simply isn’t viable for many shooters here. It IS viable in my home state however, along with the ACT, so I can at least use it in major competitions in two Australian states without having to run at lower nodes where it would otherwise be trumped by the 7 SAUM shooters. I was also attracted to the cartridge through its general design, having a 35-degree shoulder angle similar to the inherently accurate .284 Winchester. I also think the .300 WSM resembles a super-sized Dasher, another devastatingly accurate cartridge. Most .300 WSM shooters report ease of tuning, another key factor I considered.
Choice of Stock, Action, and Barrel
My gunsmith, Matt Paroz (aka MattP on the AccurateShooter Forum) is one of Australia’s top gunsmiths as well as one of Australia’s top F-Open shooters. He knows what it takes to build match-winning rifles. Matt is also an agent for McMillan stocks and I was sold on the Kestros ZR after seeing how it well it tracked — the lower center of gravity it offers cannot be underestimated once you start stepping up in caliber size. I had previously seen a couple of rifles that Matt built for an Australian F-Open team member and I was blown away not only by the quality of the builds, but how well the components worked with one another. I already own a Barnard action, a match-winning action in its own right, but I was desperate to get my hands on a Borden. I liked the fact that Jim Borden times his actions as they leave his factory, so I ordered a BRMXD, left bolt, right port, left eject. I ordered my BRMXD fully DLC-coated, for both longevity and aesthetics.
I opted for a TriggerTech Diamond trigger which has been timed to the action and offers a level of crispness the factory Barnard trigger cannot replicate. The synergy between action and trigger is just superb. I managed to get my hands on a 10-twist, 4-groove Krieger barrel that looks like a winner so far. Finished at 31″, this barrel has been super-easy to tune so far, with Berger 215gr hybrids showing very good promise. NOTE — Overall the rifle comes in 500 grams (1.1 lbs.) below F-Open max weight, so the next barrel will probably finish at 32″.
The barrel sports an Ezell tuner. I don’t touch the tuner until I’ve sorted my load and bullet seating depth. The tuner just affords me that extra flexibility in tightening up an already good grouping. At the end of the day, like any competitive shooter, I’m chasing tight vertical and horizontal, something which will run inside 1 MOA at 1000 yards. If I drop a shot, I want it to be my fault, not the rifle’s.
About my optics choice — when the chance to own a March High Master came up, I didn’t think twice. I have used March previously and got a sneak peek through an original High Master prototype which was doing the rounds in Australia. With superb image quality, it left a lasting impression. March has built up an excellent following and reputation in Australia, and so far I have to say it was money well spent. The March is held in place with a set of beefy ARC M10 rings.
The rest of my F-Open setup includes a modified SEB Mini up front, with a Rodzilla Rest top and Bryan Blake adjustable feet. I chose the SEB Mini because it has a wide, stable footprint but relatively light weight. That makes the Mini easier to transport. At the rear I use an extremely well-crafted Lenzi LR bag which sits on a custom rear plate. This heavy combination keeps things nice and planted. That aids in straight tracking.
Reloading for the .300 WSM — Process and Die Choice
When it comes to reloading, I keep it simple and don’t over-think things. I use Norma .300 WSM brass. I ensure case mouths are always deburred on the inside and out but I do not neck turn. I am set up to turn necks with a 21st Century unit, but after neck turning previously for a 6mm SLR, I just didn’t see a noticeable benefit in doing so. I always full length re-size after firing and prefer bushings, generally opting for .002″ of neck tension on anything I shoot. So far it seems to be working. With my .300 WSM I run a Redding Type-S full-length bushing die with a .335 bushing. A loaded round comes in at 0.337″ across the neck and I opted for a no-neck turn reamer which comes in at 0.343″, so there’s plenty of clearance. I use a Forster micrometer seating die. I prefer the feel of the Forster and I use Redding dry lube media to assist in smooth bullet seating.
Reloading room with MEC single-stage press on left and AutoTrickler with Force Restoration Scale on right. Note there are plenty of bullets — Kris got his supplies before the shortage.
I use an AMP Annealer and anneal after every firing. Powder charges are measured and dropped with a V3 AutoTrickler and A&D FZ500i scale. The 215gr Berger Hybrid seemed like a pretty good place to start as far as bullet selection. I point them with a Whidden bullet pointing die. Powder options can sometimes be a contentious choice and if you’re lucky you’ll get a couple of powders which will work well in any given barrel. For my .300 WSM I use Alliant Reloder 23. It is very temp-stable. My primer of choice is S&B Standard Large Rifle Primers. How does it all come together? The first nine shots through the barrel while zeroing the scope resulted in an ES of 17 and SD of 6 — promising signs for a light initial load of 63 grains.
Kris has been impressed with his .300 WSM beast: “Suffice to say I was very pleased with how things turned out! Despite the bigger bang this rifle makes, the Kestros ZR and R.A.D. 2 system made it remarkably compliant. The recoil is sharp but the R.A.D. system just takes all the sting out of it — it reminded me of shooting my old 280AI in terms of felt recoil. I was able to get back on target with a minimum of fuss and didn’t find the rifle fatiguing at all, so it gets a massive thumbs up from me.”
CONCLUSION — The .300 WSM is Very Effective for F-Open
With recent trends in F-Open equipment, such as rifle stock technology making a lower center of gravity possible, bigger F-Open options such as the .300 WSM are now quite manageable. That’s not to say this caliber is a pussy cat — it definitely kicks more than the .284s out there. But with my choice of components, the recoil is manageable and the R.A.D. 2 system takes the sting out, so I’m not left nursing a sore shoulder at the end of a stage. The rifle is off to a very positive start so far but I know it’s capable of more. The lead up to Christmas will keep me busy fine-tuning a load in time for the NSW State Title match to be held in late January 2021. With COVID-19 halting most competitive shooting in Australia in 2020, this 2021 NSW competition is sure to prove popular. I intend to have my .300 WSM rifle humming in time for it.
Kris Wilson (NSW, Australia) Talks About Competitive Shooting
When I was introduced to F-Class shooting, I was fascinated with the level of accuracy shooters were obtaining with their rifles and it was something that just drew me in. Since then it has been a gradual learning curve, not to mention the fact everyone I have met has been super friendly and willing to share their knowledge. The shooting fraternity is a great community to be part of…. Mixing it with Australia’s best is what drives me right now.
I’ve been working hard to maintain my skills and the new rifle is motivation. As reloading equipment and rifle components continue to improve, it’s a great sport which encourages learning and provides many opportunities to keep improving your shooting.
Here are two different bullet types, seated to the same CBTO length, but different COAL. Note the shiny scratches on the bullets made by the comparator tool which indicates a point on the bullet ogive near where the ogive will engage the rifling.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2 by Bryan Litz forBerger Bullets. Part One of this series focused on the importance of COAL in terms of SAAMI standards, magazine lengths, seating depths, and pressure levels. Another measure of length for loaded ammunition is highly important to precision, namely Cartridge Base to Bullet Ogive Length (CBTO).
Figure 2. Chamber throat geometry showing the bullet jump to the rifling or lands.
Look at Figure 2. Suppose the bullet was seated out of the case to the point where the base of the bullet’s nose (ogive) just contacted the beginning of the riflings (the lands) when the bolt was closed. This bullet seating configuration is referred to as touching the lands, or touching the riflings and is a very important measurement to understand for precision hand-loading. Due to the complex dynamics of internal ballistics which happen in the blink of an eye, the distance a bullet moves out of the case before it engages the riflings is highly critical to precision potential. Therefore, in order to systematically optimize the precision of his handloads, it’s critically important that the precision hand-loader understands how to alter bullet seating depth in relation to the barrel rifling. Part of the required knowledge is understanding how to accurately and repeatably measure the Cartridge Base To Ogive (CBTO) dimension. This is explained in the FULL ARTICLE.
Bryan Litz offers an extended discussion on how to measure CBTO using different tools and methods, including the Hornady OAL gauge. You can read this discussion in the full article found on the Berger Bullets website. CLICK HERE to Read Full Article.
Why Not Use CBTO as a SAAMI Standard?
If CBTO is so important to rifle accuracy, you might ask, “Why is it not listed as the SAAMI spec standard in addition to COAL?” There is one primary reason why it is not listed in the standard. This is the lack of uniformity in bullet nose shapes and measuring devices used to determine CBTO.
Benefits of Having a Uniform CBTO
There is another aspect to knowing your CBTO when checking your COAL as it pertains to performance. With good bullets, tooling, and carefully-prepared cases you can easily achieve a CBTO that varies less than +/- .001″ but your COAL can vary as much as .025″ extreme spread (or more with other brands). This is not necessarily bad and it is much better than the other way around. If you have a CBTO dimension that varies but your COAL dimension is tight (within +/- .002″) then it is most likely that your bullet is bottoming out inside the seater cone on the bullet tip. This is very bad and is to be avoided. It is normal for bullets to have precisely the same nose shape and it is also normal for these same bullets to have nose lengths that can vary as much as .025″.
Summary of Cartridge Base To Ogive (CBTO) Discussion
Here are four important considerations regarding bullet seating depth as it relates to CBTO:
1. CBTO is a critical measurement to understand for handloaders because it’s directly related to precision potential, and you control it by simply setting bullet seating depth.
2. Tools and methods for measuring CBTO vary. Most of the measurement techniques have pitfalls (which may give rise to inconsistent results) that you should understand before starting out.
3. A CBTO that produces the best precision in your rifle may not produce the best precision in someone else’s rifle. Even if you have the same rifle, same bullets, same model of comparator gauges, etc. It’s possible that the gauges are not actually the same, and measurements from one don’t translate to the same dimension for another.
4. Once you find the CBTO that produces the best precision in your rifle, it’s important to allow minimal variation in that dimension when producing quality handloads. This is achieved by using quality bullets, tooling, and properly preparing case mouths and necks for consistent seating.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
Hybrid Bullet Design — Best of Both Worlds?
Position shooters can also improve their skills by shooting different disciplines. High Power Across-the-Course shooters benefit from shooting smallbore and air rifle. Again, these targets are very small, which will encourage competitors to be more critical of their shot placement. Hunters may benefit from shooting silhouette matches, which will give them practice when shooting standing with a scoped rifle. Tactical matches may also be good, as tactical matches involve improvising shots from various positions and distances. [Editor: Many tactical matches also involve hiking or moving from position to position — this can motivate a shooter to maintain a good level of general fitness.]
The 6mmBR Norma cartridge has spawned many great variants in multiple calibers: 6mm Dasher, 6BRA, 22 BR, 22 Dasher, 30 BR and others. This article is about a handsome 22 BR Rem-action varmint rig.
Accuracy is outstanding and with Roy, Mike, my grandson and myself shooting this rifle I don’t believe it has missed more than three hogs out of over 100 we shot at one summer. This rifle is carried in a ceiling rack in the truck where it’s handy and is used by the first person that grabs it when a hog is sighted if we are moving between setups. The Varmint reticle on the Leupold (shown below) is nice for quick hold-overs as you change distances.”
The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.
Drag Models — G7 is better than G1 for Long-Range Bullets
