“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag….
Ruprecht Nennstiel, a forensic ballistics expert from Wiesbaden, Germany, has authored a great resource about bullet behavior in flight. Nennstiel’s comprehensive article, How Do Bullets Fly, explains all the forces which affect bullet flight including gravity, wind, gyroscopic effects, aerodynamic drag, and lift. Nennstiel even explains the rather arcane Magnus Force and Coriolis Effect which come into play at long ranges. Nennstiel’s remarkable resource contains many useful illustrations plus new experimental observations of bullets fired from small arms, both at short and at long ranges.
Shadowgraph of .308 Winchester Bullet
A convenient index is provided so you can study each particular force in sequence. Writing with clear, precise prose, Nennstiel explains each key factor that affects external ballistics. For starters, we all know that bullets spin when launched from a rifled barrel. But Nennstiel explains in greater detail how this spinning creates gyroscopic stability:
“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag, the plane, formed by the velocity vector ‘v’ and the longitudinal axis of the bullet. In the absence of spin, the yaw angle ‘δ’ would grow and the bullet would tumble.
If the bullet has sufficient spin, saying if it rotates fast enough about its axis of form, the gyroscopic effect takes place: the bullet’s longitudinal axis moves into the direction of the overturning moment, perpendicular to the plane of drag. This axis shift however alters the plane of drag, which then rotates about the velocity vector. This movement is called precession or slow mode oscillation.”
Raise Your Ballistic IQ
Though comprehensible to the average reader with some grounding in basic physics, Nennstiel’s work is really the equivalent of a Ph.D thesis in external ballistics. You could easily spend hours reading (and re-reading) all the primary material as well as the detailed FAQ section. But we think it’s worth plowing into How Do Bullets Fly from start to finish. We suggest you bookmark the page for future reference. You can also download the complete article for future reference and offline reading.
This article, which originally appeared in the Sierra Bullets Blog, provides a new terminology that helps describe the geometry of bullets. Once you understand the meaning of “Caliber(s) of Ogive”, you can quickly evaluate potential bullet performance by comparing listed Caliber of Ogive numeric values.
by Mark Walker, Sierra Bullets New Product Development Manager
During one of our recent product releases, we listed the “caliber of ogive” of the bullet in the product description. While some understood what that number meant, it appears that some are not aware of what the number is and why it is important. In a nutshell, the “caliber of ogive” number will tell you how sleek the front end of the bullet is. The higher the number is, the sleeker the bullet. It also makes it easy to compare the ogives of different caliber bullets. If you want to know if a certain .308 caliber bullet is sleeker than a 7mm bullet, simply compare their “caliber of ogive” numbers.
So exactly how do you figure “caliber of ogive”? If you look at the drawing of the .30 caliber 175 gr HPBT bullet #2275 (at top), you will see that the actual radius of the ogive is 2.240. If you take that 2.240 ogive radius and divide by the diameter (or caliber) of the bullet you would get 7.27 “calibers of ogive” (2.240 ÷ .308 = 7.27). (See top photo).
In a nutshell, the “caliber of ogive” number will tell you how sleek the front end of the bullet is. The higher the number is, the sleeker the bullet.
Next let’s look at the print (below) of our 6.5mm 142gr HPBT #1742 bullet for comparison. The actual radius of the ogive is 2.756. Like with the .30 caliber 175 gr HPBT bullet #2275, if you divide 2.756 by the diameter (or caliber) of the bullet you get 10.44 “calibers of ogive”.
Some people would say why not just compare the actual ogive radius dimensions instead of using the “caliber of ogive” figure. If we were comparing only bullets of the exact same diameter, then that would be a reasonable thought process. However, that idea falls apart when you start trying to compare the ogives of bullets of different diameters. As you can see with the two bullets presented above, if we compare the actual ogive radius dimensions of both bullets the difference is not much at all.
However, once again, testing has shown that the 6.5mm 142 gr HPBT #1742 has a significantly higher BC. The only way that this significant increase shows up, other than when we fire the bullets in testing, is by comparing the “caliber of ogive” measurement from both bullets.
Hopefully this will help explain what we mean when we talk about “caliber of ogive” and why it’s a handy number to use when comparing bullets. This information will help you to make an informed decision the next time you are in the market to buy bullets.
Story tip from Grant Ubl. We welcome reader submissions.
Share the post "Ballistics Linguistics: Bullet “Caliber of Ogive” Defined"
Sinclair International offers a handy tool assembly that lets you sort bullets by base to ogive length. Yes you can do this with a comparator tool attached to calipers, but the Sinclair tool really speed up the process when you’re sorting large quantities of bullets.
The $79.99 Sinclair Bullet Sorting Stand with Dial Indicator (item 749-011-469WS) comes with a heavy black granite base that stays put on your loading bench. The included analog dial indicator has a quick-release lever allowing easy placement and removal of bullets into the comparator. This lever allow the spring-loaded indicator shaft to pop up out of the way.
In the video below, Sinclair shows how to use the Bullet Sorting device. Sinclair recommend sorting in batches with variance no greater than .005 (five-thousandths) in base-to-ogive length. We like to hold tolerances even tighter, trying to hold spreads to .003. The special base comparators used with this tool are offered for $10.99 in .22 caliber, 6mm, 6.5mm, 7mm, .30 caliber, and .338 caliber. The sorting stand can also be used with Sinclair’s handy multi-caliber hex-style comparators (items 749-002-942WS, or 748-002-833WS, $19.99).
Share the post "Bullet Base-to-Ogive Sorting Tool from Sinclair Aids Accuracy"
Here’s a helpful hint for hand-loaders from Sierra Bullets. While this article focuses on Sierra’s new Tipped Match-King bullets, the recommended solutions apply to other bullet types as well. The article explains how sharp edges on a seating stem can cause a ring to be pressed into the bullet jacket — especially with compressed loads that resist downward bullet movement. Here Sierra technician Rich Machholz diagnoses the problem and provides a solution.
Solutions for Ring Marks Caused by Seating Stems
by Sierra Bullets Ballistic Technician Rich Machholz
Now that the new Tipped MatchKing® (TMK) bullets are being shipped and shooters are putting them to use I have received several calls regarding marking on the bullet ogive from the seating stem.
The cause can be traced to one of several things.
In the .223 and especially with the long, 77 grain TMK seated at 2.250” or even 2.260” most loads of Varget® and Reloder® 15 are compressed loads, sometimes heavily compressed. This puts a great deal of pressure on the bullet through the seating stem. The result of all this pressure is a mark of varying depth and appearance on the ogive of the bullet. [Editor: We have seen this issue with a variety of other bullet types/shapes as well, including non-tipped VLDs. The solution is profiling the internal cone of the seating stem to match your bullet shape.]
Some older seating stems might even bear against the tip of the bullet which can make a slight bulge in the jacket just below the junction of the resin tip and the copper jacket in a compressed load. If this is the case there is not a ready fix other than calling the die manufacturer and requesting a new deeper seating stem.
Polish Your Seating Stem to Remove Sharp Internal Edges
If the seating stem is of proper depth the culprit most generally is a thin sharp edge on the inside taper of the seating stem. This is an easy fix that can be accomplished by chucking a spare 77 grain bullet in your drill, coating it with valve grinding compound or even rubbing compound or in a pinch even tooth paste.* Remove the seating stem assembly from the seating die. Turn the drill on and put the seating stem recess over the spinning bullet with the polishing compound to break or smooth the sharp edge that is making the offending mark. This might take more than one application to get the proper polish depending upon what you use, but the more you polish the better the blend of angles which will [ensure the stem matches the bullet contours, not leaving a sharp ring].
If the above is a little more than you care to tackle you might try very fine emery cloth twisted to a point that can be inserted into the mouth to the seating stem and rotated to polish the inside to eliminate any sharp edges that might be present.
Load Advice for 77gr TMKs in the .223 Rem
And last but certainly not least. Actually, even though we don’t say you need additional data for the TMKs, remember you are dealing with heavily-compressed loads in some cases because of the additional bullet length. Due to the additional length of these new bullets and in the interest of gaining some room in the case you might consider trying a slightly faster extruded powder like BenchMark or the 4895s or an even more dense powder like the spherical H335®, CFE223 or TAC. The extra room will allow for trouble free bullet seating also.
Good luck and remember we are no further away than your telephone: 1-800-223-8799.
Share the post "Bullet Seating Advice — How to Avoid Ring Marks on Your Bullets"
SHOT Show 2016 kicks off in two weeks in Las Vegas. While at SHOT Show next month, we plan to get the “inside scoop” on new bullet designs from Berger, Hornady, Lapua, Nosler and Sierra.
A while back, at SHOT Show 2012 we chatted with Berger Ballistician Bryan Litz about Berger’s popular line of Hybrid bullets. Berger now offers a wide range of Hybrids in multiple calibers and weights. In fact, for .30-Caliber shooters, Berger now offers seven different Hybrid match bullets, with weights from 155 grains up to 230 grains. Two .338-caliber OTM Tactical Hybrids were introduced in 2012 (a 250-grainer and a 300-grainer).
Bryan tells us: “The hybrid design is Berger’s solution to the age old problem of precision vs. ease of use. This design is making life easier for handloaders as well as providing opportunities for commercial ammo loaders who need to offer a high performance round that also shoots precisely in many rifles with various chamber/throat configurations.”
For those not familiar with Hybrid bullets, the Hybrid design blends two common bullet nose shapes on the front section of the bullet (from the tip to the start of the bearing surface). Most of the curved section of the bullet has a Secant (VLD-style) ogive for low drag. This then blends in a Tangent-style ogive curve further back, where the bullet first contacts the rifling. The Tangent section makes seating depth less critical to accuracy, so the Hybrid bullet can shoot well through a range of seating depths, even though it has a very high Ballistic Coefficient (BC).
In the video we asked Bryan for recommended seating depths for 7mm and .30-Caliber Hybrid bullets. Bryan advises that, as a starting point, Hybrid bullets be seated .015″ (fifteen thousandths) off the lands in most barrels. Watch the video for more tips how to optimize your loads with Hybrid bullets.
Share the post "Hybrid Science: How to Load Hybrid Bullets for Best Accuracy"
Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. This week’s “Handloading Hump Day” post covers an important safety issue — why you should never assume that a stated “book” load for a particular bullet will be safe with an equal-weight bullet of different shape/design. The shape and bearing surface of the bullet will affect the pressure generated inside the barrel. Visit the USAMU Facebook page next Wednesday for the next installment.
Beginning Handloading, Part 13:
Extrapolating Beyond Your Data, or … “I Don’t Know, What I Don’t Know!”
Last week, we addressed several key facets of Service Rifle reloading. Today, we continue our Handloading Safety theme, focusing on not inadvertently exceeding the boundaries of known, safe data. Bullet manufacturers’ loading manuals often display three, four, or more similar-weight bullets grouped together with one set of load recipes. The manufacturer has tested these bullets and developed safe data for that group. However, seeing data in this format can tempt loaders — especially new ones — to think that ALL bullets of a given weight and caliber can interchangeably use the same load data. Actually, not so much.
The researchers ensure their data is safe with the bullet yielding the highest pressure. Thus, all others in that group should produce equal or less pressure, and they are safe using this data.
However, bullet designs include many variables such as different bearing surface lengths, hardness, and even slight variations in diameter. These can occasionally range up to 0.001” by design. Thus, choosing untested bullets of the same weight and caliber, and using them with data not developed for them can yield excess pressures.
This is only one of the countless reasons not to begin at or very near the highest pressure loads during load development. Always begin at the starting load and look for pressure signs as one increases powder charges.
Bullet bearing surface length (BSL) is often overlooked when considering maximum safe powder charges and pressures. In photo 1 (below), note the differences in the bullets’ appearance. All three are 7mm, and their maximum weight difference is just five grains. Yet, the traditional round nose, flat base design on the left appears to have much more BSL than the sleeker match bullets. All things being equal, based on appearance, the RN/FB bullet seems likely to reach maximum pressure with significantly less powder than the other two designs.
Photo 1: Three Near-Equal-Weight 7mm Bullets with Different Shapes
Due to time constraints, the writer used an approximate, direct measurement approach to assess the bullets’ different BSLs. While fairly repeatable, the results were far from ballistics engineer-grade. Still, they are adequate for this example.
Bullet 1 (L-R), the RN/FB, has a very slight taper and only reaches its full diameter (0.284”) very near the cannelure. This taper is often seen on similar bullets — it helps reduce pressures with good accuracy. The calculated BSL of Bullet 1 was ~0.324”. The BSL of Bullet 2, in the center, was ~0.430”, and Bullet 3’s was ~ 0.463”. Obviously, bullets can be visually deceiving as to BSL!
Some might be tempted to use a bullet ogive comparator (or two) to measure bullets’ true BSL for comparison’s sake. Unfortunately, comparators don’t typically measure maximum bullet diameter and this approach can be deceiving.
Photo 2: The Perils of Measuring Bearing Surface Length with Comparators
In Photo 2, two 7mm comparators have been installed on a dial caliper in an attempt to measure BSL. Using this approach, the BSLs differed sharply from the original [measurements]. The comparator-measured Bullet 1 BSL was 0.694” vs. 0.324” (original), Bullet 2 was 0.601” (comparator) vs. 0.430” (original), and Bullet 3 (shown in Photo 2) was 0.602” (comparator) vs. 0.463” (original). [Editor’s comment — Note the very large difference for Bullet 1, masking the fact that the true full diameter on this bullet starts very far back.]
Please join us again next week as we examine other lesser-discussed variables that affect pressure and velocity during handload development. In the meantime, stay safe, and favor center!
Share the post "Handloading Safety Tip — Bullet Bearing Surface and Pressure"
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.
Figure 4. Two different bullet shapes, 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 riflings.
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.
At SHOT Show we checked out a versatile and well-designed new tool from Forster Products — the new Datum Dial Ammunition Measurement System. This handy device measures a variety of important dimensions: 1) cartridge headspace from base of case to shoulder datum; 2) cartridge length from base of case to bullet ogive; 3) bullet base to bullet ogive; and 4) bullet bearing surface (requires two tools).
The complete Datum Dial Kit consists of a dial-holder mount and three precision machined dials. The mount clamps to your sliding-jaw calipers. The mount holds a black ring or one of two supplied gold rings. The black ring has 5 precision-diameter holes that let you check headspace (on shoulder datum) for nearly all modern cartridge types.
Swap in one of two available gold rings to measure to bullet ogive index points. The two gold dials (five holes each) give you 10 different bullet diameter choices, covering the vast majority of common pistol and rifle bullet sizes. This lets you measure both base of bullet to ogive and base of cartridge case to bullet ogive. We really like this dual functionality, as it allows you to quickly sort bullets, plus you can measure your loaded rounds as they come out of the seating die. I have found that accuracy is enhanced when you maintain close base-to-ogive tolerances on your loaded rounds.
Watch Video to See Datum Dial Features and Functions
Replace a Bin Full of Comparator Inserts
It is important to understand that the Datum Dial system replaces a comparator body and a complete set of caliber-specific comparator inserts. You no longer need a box full of inserts, with one for each caliber that you load. The Datum Dial Complete Kit includes: One dial-holder mount (which clamps on your calipers), one black headspace dial, two (2) gold bullet diameter dials, and a plastic storage box. The Datum Dial Kit is available right now. MSRP is $157.00, and “street price” should be $20 or so lower. Additional dials or caliper jaw mounts are sold separately.
Share the post "Forster Products’ New Datum Dial Ammo Measurement System"
SHOT Show 2013 kicks off in two weeks in Las Vegas. One of our top priorities is to talk with the bullet makers from Berger, Hornady, Lapua, and Nosler.
At SHOT Show 2012 we chatted with Berger Ballistician Bryan Litz about Berger’s popular line of Hybrid bullets. Berger now offers a wide range of Hybrids in multiple calibers and weights. In fact, for .30-Caliber shooters, Berger now offers six different Hybrid match bullets, with weights from 155 grains up to 230 grains. New .338 Cal Tactical Hybrids were released in 2012 and big .375 Cal, and .408 Cal Hybrids are in the works (read more below).
Bryan tells us: “The hybrid design is Berger’s solution to the age old problem of precision vs. ease of use. This design is making life easier for handloaders as well as providing opportunities for commercial ammo loaders who need to offer a high performance round that also shoots precisely in many rifles with various chamber/throat configurations.”
For those not familiar with Hybrid bullets, the Hybrid design blends two common bullet nose shapes on the front section of the bullet (from the tip to the start of the bearing surface). Most of the curved section of the bullet has a Secant (VLD-style) ogive for low drag. This then blends in a Tangent-style ogive curve further back, where the bullet first contacts the rifling. The Tangent section makes seating depth less critical to accuracy, so the Hybrid bullet can shoot well through a range of seating depths, even though it has a very high Ballistic Coefficient (BC).
In the video we asked Bryan for recommended seating depths for 7mm and .30-Caliber Hybrid bullets. Bryan advises that, as a starting point, Hybrid bullets be seated .015″ (fifteen thousandths) off the lands in most barrels. Watch the video for more tips how to optimize your loads with Hybrid bullets.
Berger is Developing New Large-Caliber and Hunting Hybrids
In related news, Berger announced that it will be offering a series of .338-caliber Hybrids. First Berger is reintroducing the Gen 1 .338 Cal, 300gr Hybrid bullet in Berger’s Hunting line. Berger will also be making a 250gr Hybrid Hunting bullet using the same type of jacket as the original Gen 1 300gr Hybrid bullet. In addition, Berger has released a .338 Cal 250gr Match Hybrid OTM Tactical bullet, along with a 300gr Match Hybrid OTM Tactical projectile.
More big bullets are on the drawing board. Our source says “.375 Caliber and then .408 Caliber are the next new calibers to be made at Berger”. These are in the design phase, and Berger needs to build a new machine, so the .375s and .408s will not be available until 2013 at the earliest.
Share the post "Berger Hybrid Bullets — What You Need to Know"
The big news at Berger Bullets for 2011 is the Hybrid. No, Walt isn’t switching to a Prius… but Berger IS committing to the dual-shape hybrid design for a full range of calibers. The hybrid design combines a secant ogive (VLD-style) profile in the front of the bullet, with a tangent profile further back. This gives bullets the high BC of the VLD-style bullets, but the tangent section makes the bullets less sensitive to small variations in seating depth. The tangent ogive is a more gentle curve. Tangent ogive bullets, generally speaking, are more “forgiving” or easier to tune. They also will stay in tune better as a barrel throat erodes.
What Berger has done with the hybrid bullet is put an easy-tuning geometry on the part of the bullet that actually engages the rifling, while using a more streamlined front end for improved ballistics. This hybrid design was introduced in 2010 with hybrid 7mm and .338 bullets. Both new hybrid designs proved very successful. The hybrid designs were developed with significant design input from Bryan Litz, Berger’s ballistician. Before Bryan signed on with Berger, he literally worked as a rocket scientist, so he knows something about low-drag shapes. In the video below, Bryan explains why Berger will introduced more hybrid bullets in more calibers, in the months ahead. Bryan also talks about other products Berger has in the works, including its much-awaited reloading manual.
Share the post "SHOT Show Report: Berger Crafts Hybrids in More Calibers"
Berger Bullets has just released its new .338-caliber “hybrid” bullet, Berger’s first-ever projectile larger than .30 caliber. The new bullet has a very high ballistic coefficient (BC): 0.891 under the G1 model, and 0.455 under the newer G7 standard for boat-tail bullets. That high BC should translate into exceptional long-range performance. According to Berger, the BC of the new Berger .338 bullet BC is roughly 14% better than the BCs of other .338-caliber 300gr offerings from Sierra and Lapua. This claim is supported by testing done on all three bullets and published in a detailed Bullet Comparison Report (PDF). The new .338 Hybrid bullets will be sold in 50-count and 250-count boxes. To order, call Berger’s Tech-Line, (714) 447-5458.
The key design feature of the new .338 bullet is its hybrid ogive, i.e. a shape that combines both tangent and secant geometry. A tangent ogive meets the bearing surface very smoothly, whereas a secant ogive has an abrupt juncture with the bearing surface. The figure below shows the geometric differences between a tangent and a secant ogive, as well as the strengths and weaknesses of each.
Practical Considerations — Load Length and Twist Rate
The superior ballistic performance of the 300gr Hybrid .338 is primarily due to the very long ogive and boat tail. However, that super-long bullet length can create some issues. Berger’s new .338 Hybrid bullets are so long that loaded rounds may not fit some magazines comfortably, unless you deep-seat the bullets, which cuts down on usable case capacity. If your loaded rounds with the new .338s are too long for your magazine, single-feeding is recommended. In addition, and this is IMPORTANT, to get optimal performance with the new bullets, you may want to extend the throat in your chamber. This can be done relatively easily by a competent gunsmith using a throating reamer. We caution, however, once the throat is pushed out, you can’t go back to a shorter throat without setting back the entire barrel.
The new .338 Hybrid bullets should stabilize well with a 1:10″ twist at the velocities achievable with popular .338 magnum cartridges. However, according to Bryan Litz, Berger’s Ballistician, at extreme long ranges (beyond one mile), as the .388 bullet goes trans-sonic, it may need more spin. As the bullet slows down into the trans-sonic range, extra stability is required — something you get by spinning the bullet faster. So, for those guys planning to shoot at one mile or beyond, Berger recommends a faster twist-rate. The faster twist provides more spin-stabilization at very long ranges. But for 1000-yard shooting, you don’t need to be concerned about trans-sonic stability. As Bryan explains: “So as long as you keep your shots under 1 mile, the 1:10″ twist is plenty adequate.”
Berger Bullets Video Update (Eric Stecker talks about the new .338 Hybrid and other matters.)
Share the post "Berger Bullets Releases New .338 Hybrid (Dual-Ogive) Bullet"
You may have heard rumors about a new 100gr projectile from Berger Bullets. Eric Stecker, Berger’s Master Bulletsmith, confirmed that there will be not one but TWO new 100gr match bullets coming soon from Berger, one in 6mm and one in 6.5mm. These are both boat-tail designs using J4 jackets. Eric explains: “Both these bullets are based on Berger’s proven designs, with standard length ogives and 9° boat-tails. Nothing radical. They are built in response to shooters’ requests to expand our bullet line-up to include new weight options in 6mm and 6.5mm.”
New 100gr 6.5mm Bullet for High Power
Berger’s new 6.5mm 100gr BT Target projectile provides a low-recoil, lighter-weight option for target rifle shooters using the 6.5×47 Lapua, 6.5 Creedmoor, 260 Rem, and 6.5-284 cartridges. The new 6.5mm 100-grainer was created in response to requests from High Power and Across-the-Course shooters for a lighter-recoiling, accurate boat-tail bullet for “short line” work. We predict this bullet may also work well for varmint and small-game hunters. This bullet features a short boat-tail and a “mildly secant” design which should work well either seated into the lands or jumped away from the lands. Bryan Litz says: “it’s definitely not a VLD, but it has a different ogive curve than a typical tangent-ogive bullet.” The shorter length of the 100gr bullet, compared to 140gr-class 6.5mm bullets, should also allow tactical shooters to easily load their ammo to mag length. The calculated BC of the new bullet is 0.370, significantly higher than flat-based 100gr 6.5mm bullets from other manufacturers. A minimum twist rate of 1:10” is recommended for Berger’s hew 6.5mm 100gr Target Bullet.
New 100gr 6mm Match Bullet — More Velocity Than 105/108
Long-range benchresters have had great success with the Berger 108gr match bullet, introduced in 2007. Given the popularity of its tangent-ogive 108, Berger has been developing a shorter, lighter version, which can shoot faster than the 108 in small cartridges such as the 6mmBR, 6mmAR (6-6.5 Grendel), and 6 PPC. The new 6mm 100-grainer will be very similar to the 108. The 100 has the same ogive curve and boat-tail as the 108 but has a shorter OAL and shorter bearing surface (0.368″ vs. 0.409″). A minimum twist rate of 1:8” is recommended for the new 100 — same as for the 108. In a 6BR rifle, the 100-grainer’s reduced bearing surface, combined with reduced mass, should enable Berger’s new 100gr 6mm bullet to fly 50-70 fps faster than the 108 (with charges of equal pressure).
However, there is a trade-off. Being shorter and lighter, the 100-grainer has a lower BC compared to its 108gr big brother. While the Berger 108 has a 0.511 BC, the calculated BC for the 100-grainer is 0.475. That BC difference will show up at long range, but the extra speed of the lighter bullet may enable it to reach a higher, optimal “velocity node” which may deliver superior accuracy in some rifles. We will be testing the new 100-grainer soon. In a 6BR that might max out at 2850 fps with the 108s, we predict the 100gr Berger should run close to 2900 fps. In a 6BR that delivers 2900 fps currently with the 108s, you may see 2950 fps (or more) with the new Berger 100s. The 2900-2950 fps speed range is a well-known “accuracy node” for both 6mm and 6.5mm bullets.
Share the post "Berger Introduces 6.5mm and 6mm 100-grain Bullets"
Sinclair International offers a handy tool assembly that lets you sort bullets by base to ogive length. Yes you can do this with a comparator tool attached to calipers, but the Sinclair tool really speed up the process when you’re sorting large quantities of bullets.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2
The complete Datum Dial Kit consists of a dial-holder mount and three precision machined dials. The mount clamps to your sliding-jaw calipers. The mount holds a black ring or one of two supplied gold rings. The black ring has 5 precision-diameter holes that let you check headspace (on shoulder datum) for nearly all modern cartridge types.
