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 to that 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 preferrable 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.]
Becigneul Case Turning Motor, by German Salazar
Although there have been a variety of similar devices and ‘case lathes’ offered for sale in the past, they’ve been priced fairly high. Paul’s unit is reasonably priced ($220.00) and built like a tank. The motor turns at about 180 rpm which is just right for neck turning. What’s really nice is that the motor has enough torque to hold its speed throughout the whole operation and a/c power to run all day long!
The unit’s design is fairly straight-forward: a surplus electric motor turns a Forster case-holding collet. Paul makes a nice knurled collar to open and close the collet.Power is controlled by a household type wall switch attached to a long cabe. The whole assembly is mounted on a nice hardwood base.
Video of Paul Becigneul’s Case Turning Motor in Use
In operation, it works very well. The collet has enough clamping power to hold the case after a quick hand-tightening, no wrench is needed (although you can use one if you are so inclined). A quarter turn of the collar opens the collet and a quick turn of the wrist tightens it back up. As with any powered case neck turning device, the case wobbles a bit as it turns. This doesn’t matter a bit as the turning cutter is held in your hand (which is free to move) and the cutter’s arbor is the actual alignment device. The wobble is the same or less than what I had using a power screwdriver with a K&M holder.
For more information, email Paul Becigneul via: pbike4466 [at] directv.net. In 2012, the basic unit cost $220.00 each collet was $10 and shipping is $20 to most U.S. locations.
Editor’s Comment: In the video, Paul uniforms case flash-holes with a Lyman tool (from the inside) and then uniforms primer pockets (from the outside) with a K&M tool. While we do believe that flash-holes should be inspected to ensure there are no obstructions or flakes blocking the hole, we have not found that flash-hole or primer-pocket uniforming produced measurable improvements in accuracy with Lapua 6mmBR brass. In fact, in our tests using a manual K&M flash-hole uniformer, ES/SD actually got worse after the flash-holes were “uniformed”.
Keep in mind also that many deburring tools for 0.059 (PPC-size) flash-holes actually over-cut substantially, reaming the holes to as wide as 0.068″. The Lapua PPC/BR flash hole is spec’d at 1.5mm, which works out to 0.059055″. Most of the PPC/BR flash-hole uniforming tools on the market use a 1/16″ bit which is nominally 0.0625″, but these often run oversize — up to 0.067″. If you like to uniform your primer pockets, be our guest (this can be useful with lesser-quality brass). But before pocket-uniforming dozens of cases, you might do a comparison test (by shooting uniformed vs. un-uniformed ammo) to see whether this operation actually improves accuracy with the brass you are using.
In our Shooters’ Forum a reader recently asked: “How much neck tension should I use?” This prompted a Forum discussion in which other Forum members recommended a specific number based on their experience, such as .001″, .002″, or .003″. These numbers, as commonly used, correspond to the difference between case-neck OD after sizing and the neck OD of a loaded round, with bullet in place. In other words, the numbers refer to the nominal amount of interference fit (after sizing).
While these commonly-used “tension numbers” (of .001″, .002″ etc.) can be useful as starting points, neck tension is actually a fairly complex subject. The actual amount of “grip” on the bullet is a function of many factors, of which neck-OD reduction during sizing is just one. Understanding these many factors will help you maintain consistent neck tension as your brass “evolves” over the course of multiple reloadings.
Neck Tension (i.e. Grip on Bullets) Is a Complex Phenomenon
While we certainly have considerable control over neck tension by using tighter or looser bushings (with smaller or bigger Inside Diameters), bushing size is only one factor at work. It’s important to understand the multiple factors that can increase or decrease the resistance to bullet release. Think in terms of overall brass-on-bullet “grip” instead of just bushing size.
One needs to understand that bushing size isn’t the beginning and end of neck tension questions, because, even if bushing size is held constant, the amount of bullet “grip” can change dramatically as the condition of your brass changes. Bullet “grip” can also change if you alter your seating depth significantly, and it can even change if you ultrasonically clean your cases.
Bullet grip is affected by many things, such as:
1. Neck-wall thickness.
2. Amount of bearing surface (shank) in the neck.
3. Surface condition inside of neck (residual carbon can act as a lubricant; ultrasonic cleaning makes necks “grabby”).
4. Length of neck (e.g. 6BR neck vs. 6BRX).
5. Whether or not the bullets have an anti-friction coating.
6. The springiness of the brass (which is related to degree of work-hardening; number of firings etc.)
7. The bullet jacket material.
8. The outside diameter of the bullet and whether it has a pressure ridge.
9. The time duration between bullet seating and actual firing (necks can stiffen with time).
10. How often the brass is annealed
— and there are others…
Seating Depth Changes Can Increase or Decrease Grip on Bullet
You can do this simple experiment. Seat a boat-tail bullet in your sized neck with .150″ of bearing surface (shank) in the neck. Now remove the bullet with an impact hammer. Next, take another identical bullet and seat it with .300″ of bearing surface in another sized case (same bushing size/same nominal tension). You’ll find the deeper-seated bullet is gripped much harder.
Neck-Wall Thickness is Important Too
I have also found that thinner necks, particularly the very thin necks used by many PPC shooters, require more sizing to give equivalent “grip”. Again, do your own experiment. Seat a bullet in a case turned to .008″ neckwall thickness and sized down .003″. Now compare that to a case with .014″ neckwall thickness and sized down .0015″. You may find that the bullet in the thin necks actually pulls out easier, though it supposedly has more “neck tension”, if one were to consider bushing size alone.
In practical terms, because thick necks are less elastic than very thin necks, when you turn necks you may need to run tighter bushings to maintain the same amount of actual grip on the bullets (as compared to no-turn brass). Consequently, I suspect the guys using .0015″ “tension” on no-turn brass may be a lot closer to the guys using .003″ “tension” on turned necks than either group may realize.
Toward a Better Definition of Neck Tension
As a convenient short-cut, we tend to describe neck tension by bushing size alone. When a guy says, “I run .002 neck tension”, that normally means he is using a die/bushing that sizes the necks .002″ smaller than a loaded round. Well we know something about his post-sizing neck OD, but do we really have a reliable idea about how much force is required to release his bullets? Maybe not… This use of the term “neck tension” when we are really only describing the amount of neck diameter reduction with a die/bushing is really kind of incomplete.
My point here is that it is overly simplistic to ask, “should I load with .001 tension or .003?” In reality, an .001″ reduction (after springback) on a thick neck might provide MORE “grip” on a deep-seated bullet than an .003″ reduction on a very thin-walled neck holding a bullet with minimal bearing surface in the neck. Bushing ID is something we can easily measure and verify. We use bushing size as a descriptor of neck tension because it is convenient and because the other important factors are hard to quantify. But those factors shouldn’t be ignored if you want to maintain consistent neck tension for optimal accuracy.
Consistency and accuracy — that’s really what this all about isn’t it? We want to find the best neck tension for accuracy, and then maintain that amount of grip-on-bullet over time. To do that you need to look not only at your bushing size, but also at how your brass has changed (work-hardened) with time, and whether other variables (such as the amount of carbon in the neck) have changed. Ultimately, optimal neck tension must be ascertained experimentally. You have to go out and test empirically to see what works, in YOUR rifle, with YOUR bullets and YOUR brass. And you may have to change the nominal tension setting (i.e. bushing size) as your brass work-hardens or IF YOU CHANGE SEATING DEPTHS.
Remember that bushing size alone does not tell us all we need to know about the neck’s true “holding power” on a bullet, or the energy required for bullet release. True bullet grip is a more complicated phenomenon, one that is affected by numerous factors, some of which are very hard to quantify.
By Michael Bussard, edited by John B. Allen, David Kosowski, Charles F. Priore, Jr.
If you’re a serious shooter, the latest 4th Edition of the Ammo Encyclopedia (released in August, 2012), belongs in your library. This 972-page book is probably the most comprehensive and up-to-date book in print covering current and obsolete cartridges and shotshells. Bussard’s Ammo Encyclopedia is a massive resource work. The 4th Edition now boasts over 100 chapters.
One of the best features is a 12-page color section depicting actual size drawings of 265 current rimfire/centerfire cartridges and shotshells. You won’t find that many “life-size” cartridge drawings in one place even on the internet. Cartridge profiles and ballistic charts have been expanded to include all new factory cartridges. The authors have even included air rifle pellets and historical images and charts. Softcover, 972 pages.
Comments from guys who bought the book:
“This book contains a vast array of information on many modern and even obsolete ammunition. Definately recommend for any modern reloader novice or experienced.” – Duggaboy460
“It’s a great reference book for individuals who reload their own ammunition. There is a lot more info in this Edition. Everyone who likes this information should have it in their library.” – Reloader
“I like the general and technical comments that are available for each and every cartridge. Information that predicts if a cartridge will stay in production for many more years or rapidly become obsolete.” – RSL1
On his Riflemans’ Journal blog, German Salazar wrote an excellent article about cartridge Case-Head Separation. We strongly recommend that you read this article. German examines the causes of this serious problem and he explains the ways you can inspect your brass to minimize the risk of a case-head separation. As cases get fired multiple times and then resized during reloading, the cases can stretch. Typically, there is a point in the lower section of the case where the case-walls thin out. This is your “danger zone” and you need to watch for tell-tale signs of weakening.
The photo below shows a case sectioned so that you can see where the case wall becomes thinner near the web. German scribed a little arrow into the soot inside the case pointing to the thinned area. This case hadn’t split yet, but it most likely would do so after one or two more firings.
One great tip offered by German Salazar involves using a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. German explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case. If you do this every time you reload, on at least 15% of your cases, you’ll develop a good feel for what the thin spot feels like and how it gets worse as the case is reloaded more times. And if you’re loading the night before a match and feel pressured for time — don’t skip this step!”
The Hornady Lock N Load AutoCharge Electronic Scale/Dispenser is now on sale for under $200.00. Grafs.com has the Hornady AutoCharge for $194.99 (with $5.95 flat sh/h) and Amazon.com offers the AutoCharge for $195.00 with FREE ‘Super-Saver’ shipping. If you are looking for an affordable combination digital scale and powder dispenser, this is very attractive pricing. By comparison, the RCBS ChargeMaster is currently on sale for $299.99 at Sinclair International. So you can save at least $105.00 by buying RED instead of GREEN.
While we have a lot of positive experience with the RCBS Chargemaster, we haven’t done any long-term testing of the Hornady AutoCharge. However, user reviews have generally been positive. We suggest you do your own research and then make your own decision. Both the Hornady LnL AutoCharge and RCBS ChargeMaster offer load precision to ±0.1 grains. Both the Hornady Autocharge and the RCBS ChargeMaster are sold with a one-year manufacturers warranty.
Features and Specifications:
Scale capacity of 1000 grains
Easy-to-operate keypad
Large backlit display
Automatic and manual dispense options
Trickle function
Three speed settings
Easy Outflow Powder Drain
Overcharge protection
One-year manufactuer’s warranty
This Youtube video shows the Hornady Lock-N-Load AutoCharge in action.
If you want to learn more about the Hornady AutoCharge, there is a detailed review in Shooting.com.au, a popular Aussie gun forum. This product review features actual test results along with lots of sharp, jumbo-sized photos. Here is the summary of the reviewer’s test results: “Weighing [20 charges of a stick powder] on a Redding beam scale (the only other scale I have) showed that 12 were spot on and the remainder we fairly equally split between 0.1 grain under and 0.1 grain over according to this scale. I consider this to be more than adequate for me.”
The new 2013 Annual Hodgdon Reloading Manual (the 10th Annual Edition) has just been released. The manual now contains over 5000 loads, with updates for 37 rifle and pistol cartridges. You’ll also find data for Hodgdon’s popular, new CFE-223 reduced-fouling powder — CFE-223 load info has been added for 19 more cartridges. Varmint hunters will be pleased to see the addition of complete data for the popular 17 Hornet. Along with comprehensive load data, the 2013 Annual Manual offers authoritative articles by top gun and outdoor industry writers working with the editors of Shooting Times magazine.
You’ll find the 2013 Hodgdon manual at newsstands and gun stores in early 2013, priced at $8.99. (Some stores already have the 2013 Manual on the shelves.) You can also order direct by visiting Hodgdon.com or calling (913) 362-9455. (Direct sales price is $11.99 including postage.)
If you are looking for an affordable precision scale, the GemPro 250 scale is now on sale for just $145.00 at Amazon.com. This scale offers 0.02 grain resolution, good enough to trickle kernel by kernel. The GemPro 250 comes with a 30-year warranty for American buyers. As this scale weighs more precisely than popular digital powder scale/dispensers, you can use the digital dispenser to throw a “close” charge and then fine-tune your load with the GemPro, kernel by kernel.
by Bill Schnauffer (aka Cover Dog)
The Importance of Precise Loads for Long-Range Shooting
The reloading scale is the life blood of anyone’s loading bench. It’s used for everything from weighing powders to cases or bullets and yes even primers. I would have never considered weighing primers but that is one of the many things I learned the weekend of May 20-22, 2011 at The Original Pennsylvania 1000-Yard Bench Rest Club’s Bench Rest Instructional School. All aspects of reloading for 1000-yard BR have to be identical. Your brass, bullets, powder and primers all have to weigh the same, for all your sighters and your 10 record shots, if you want any chance of being competitive. This can only become a reality if your scale is up to the task. Everything you do when shooting at 1000 yards is magnified 10x and your scale needs to be above all else, accurate and repeatable.
I thought that a scale accurate to 1/10th of a grain was good enough. Not so in the long range BR game. Scales need to be accurate to at least 5/100ths of a grain or better if you can afford it. This prompted my search for such a scale.
GemPro Is Half the Price of Denver Instrument MXX-123
I have read reviews for several of the better scales used for reloading including the Accu-Lab VIC 123 (now replaced by the Sartorius Acculab AY123110V). The [AY123 seriess] scales are accurate to 2/100ths of a grain, but is also a scale that many felt was affected by RF interference and the slightest air movement made it drift. This was due in part because of the strain gauge technology that is used in the manufacture of this scale. And with parts not readily available, the lead time for one is you want it is over 20 weeks. The Denver Instrument MXX-123 also had a good review but the current version, [Sartorius Acculab AY123110V], is into the $320 price range. And this is out of reach for many reloaders.
This now brings me to the My Weigh GemPro 250. It uses True-Division German HBM sensors and professional components in the manufacture of this scale. It has a 50 gram weight capacity (771.72 grains) and accuracy down to 2/100ths of a grain. It features seven (7) weighing modes as listed below. And with a retail price in the $145.00 range, this is a scale that most reloaders could afford for their reloading bench. And you won’t be pressed for room on that bench. The scale is very compact, measuring 5.25″ X 3.75″ X 2.5″.
Product Sale Tip by Boyd Allen. We welcome Reader Submissions.
The new 829-page Berger Reloading Manual is now on sale at MidwayUSA.com for $24.99. This is a very good deal. This impressive new resource sells elsewhere for $29.00. At this price, you may want to pick up a couple and give one as a gift.
Book Sale Tip by EdLongrange. We welcome reader submissions.
How to Set Up Your Full Length Sizing Die
by Ron Dague, Sinclair International Technician
From Sinclair’s Reloading Press Blog
At Sinclair International, we are often asked for a fool-proof method to set up a full-length sizing die, and begin reloading our fired cases. The method used by many target shooters today is to set up your full length die to closely match your rifle chamber and minimally full-length size your cases –as little as .001″ for bolt-action rifles. I prefer to use this method for all of my bolt-action cartridges.
STEP ONE
I like to de-prime five (5) cases (de-prime only, do not full length resize) and measure from the base of the case to the shoulder with our Sinclair Comparator Body (09-1000) and Bump Gage Insert(09-10200). We refer to this as our headspace measurement. Our Electronic Caliper (#MIC-14) works well and may be pre-set at .000” making this headspace measurement easy to capture. The Sinclair Comparator/Gauge Body and Bump Gage Inserts make this task fairly simple. L.E. Wilson Tools & Gages, Hornady Manufacturing, and RCBS all make similar units to achieve your headspace measurement.
STEP TWO
With your full-length die threaded into your reloading press, loosen the lock ring and run the press ram up toward the full length die with a shell holder in place (with no case). Then, screw the die toward the shell holder until it stops. Back the die out of the press and away from the shell holder one full turn and set the lock ring finger tight.
STEP THREE
Lubricate each of the cases with your favorite sizing lube (my favorite is Imperial Sizing Die Wax) and resize a case. Again, take a headspace measurement from base to shoulder. [When running the case up into the die, be sure the press ram moves the full limit of its upward travel.] If there’s no change in the measurement from the fired dimension, loosen the die lock ring and turn the full length sizing die downward 1/8 of a turn. [Editor’s Note: You’ll need to use smaller turn amounts as you get close to the desired amount of bump. We suggest moving just a few degrees of die rotation at a time once you’ve reached the point where the die hits the shoulder without moving it back.] Now repeat the sizing process with a second lubricated case and take the measurement again. Keep rotating the die downward gradually (in small increments) and repeat the case sizing process until you see approx-imately .001”-.002” reduction to your fired headspace measurement. We prefer a headspace reduction of approximately .001″ – .002″ for bolt action rifles and .003″ – .005″ for semi-auto rifles. You can adjust to your rifle as to what works best. Don’t forget to load 10 rounds or so and try them from the rifle’s magazine to make sure they function properly.
Full-length Sizing vs. Neck-Sizing
Just a quick word on neck sizing…..I have personally never been a big fan of neck sizing. Often times when I put neck sized cases back in the rifle, the bolt would close with some drag, or it would be a bit “snug”. This was mostly recognized with factory rifles. I didn’t have any problems with accuracy, just with cycling the action for a follow up shot. If your rifle is custom chambered with the action straightened and trued, neck sizing will work well on 4-5 firing’s and then you will need to full length size or use a body die to set the shoulders back when the cases begin to “stick”. Hope these tips help make the use of a headspace gauge and full length die set up much easier.
Ron Dague
Sinclair Tech and Reloading Instructor
800-717-8211
rond@sinclairintl.com
Reloading Tip Courtesy Sinclair Int’l; Story Sourced by Edlongrange
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
In our 
Neck-Wall Thickness is Important Too
By Michael Bussard, edited by John B. Allen, David Kosowski, Charles F. Priore, Jr.
On his 
The Hornady Lock N Load AutoCharge Electronic Scale/Dispenser is now on sale for under $200.00. 
If you are looking for an affordable precision scale, the GemPro 250 scale is now on sale for just $145.00 at 
STEP TWO
