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 As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.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.
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.
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.
Many readers will be driving across multiple states this summer to attend competitions. Other shooters will be heading out of state for a game hunt or prairie dog safari. For $13.95 you can purchase a state-by-state Traveler’s Guide to firearms laws. This book can help ensure you comply with all state laws during your trip. Highways Magazine states: “If you carry a weapon in your rig, you need this book.” This 68-page guide covers all firearms types and all 50 states. It even has info for Canada and Mexico. The latest edition of the Traveler’s Guide, updated with 50 changes for 2013, is now shipping.
The Traveler’s Guide to the Firearm Laws of the Fifty States has sold more than 950,000 copies since it was first released in 1996. The book’s author, Attorney J. Scott Kappas, has written numerous magazine articles and has appeared on television, explaining the unexpected pitfalls that shooters may encounter when traveling with firearms. Along with being an attorney, Mr. Kappas serves as a director on the Board of the Kentucky Firearms Foundation, and Kappas is a Class III firearms dealer.
The Traveler’s Guide is especially useful for shooters traveling in RVs and motorhomes. The American Rifleman Magazine declared: “This book is a must-have for truck drivers, motor home enthusiasts, campers and other travelers…easy to read and understand, well-organized and concise….” One reader from Texas adds: “I used to think that my RV was the same as my home when it came to gun carry….the Traveler’s Guide set me straight. Now I know my motorhome is subject to the same laws as any vehicle when it comes to guns.”
These days, online gun auctions are busier than ever. Many folks are purchasing arms for the first time, and sellers are enjoying good prices for their wares based on increased demand. Some people even think that guns may be a safer investment than real estate or bonds at this time. That’s questionable, but this Editor finds it ironic that most of his guns have held their value while the price of gold has dropped over 25% in the past couple of years. For those with extensive collections (and gun safes bursting at the seams), this may be an opportune time to “thin out” your holding and sell off little-used (or less favored) rifles and pistols.
To assist our readers with the gun buying and selling process, we’ve prepared a guide to Selling Your Stuff Online. This quick guide surveys the major online sales and auction sites, comparing their fees and features. The costs are NOT all the same. Did you know that Gunbroker.com charges sellers 5% of the first $25.00, plus 2.5% of the value from $25.00 – $1000.00, plus 1.5% of the remaining value ($1000+). For a $3000.00 gun that’s over $50.00 in sales commissions! That’s why many sellers prefer to list their rifles on Benchrest.com for just $3.00, or right here on AccurateShooter.com for FREE!
1. Include Good, Sharp Photos: A custom rifle or expensive optic will sell two to three times as quickly, at a higher price, if you include good sharp photos. We can’t over-emphasize the importance of good photos. For all products, show multiple angles, and include the original boxes if you still have them. For a rifle, include detail shots as well as a photo of the complete gun.
2. Resize Your Photos Before Posting: Remember that many readers have monitors that only display 800-1000 pixels in screen width. We recommend you size your photos down to 600×480 pixels, or 800×600 at the most.
3. Be Fair and Complete in Your Description: Buyers appreciate honesty and thoroughness in product descriptions. Potential buyers want details. For a rifle, list the gunsmith, barrel-maker, round count, and provide the specifications. If the rifle has a winning competition history, say so. Always highlight the positives in your description, but you should disclose significant flaws. A buyer will be more willing to purchase if he thinks the seller is 100% honest.
4. Don’t Forget Contact Info: We’re amazed by how many adverts omit key contact info. In a forum classified ad, include your phone number, and email address in your listing. Include a first name, e.g. “Ask for Dan.” We also suggest you list your residence city and state. Some buyers will prefer to buy from a seller in their home state.
5. Make the Price Attractive: Buyers, everywhere, are looking for good deals. If you want your item to move quickly, set the price accordingly and don’t expect top dollar. Check comparable listings and then discount by 10-15% if you want the item to move fast.
6. Include a Call to Action: Advertisements can be twice as effective if they include a “Call to Action”, i.e. a statement that directly inspires the potential buyer to respond. Sample calls to action are: “Free Shipping — today only.” Or, you can use a time limit: “Special Sale Price good ’til the end of the month. Act soon”.
Classified Advert vs. Auctions For benchrest, F-Class, Silhouette, Tactical or High Power rifles, you may get the best results posting a For Sale ad on a Forum that caters to the right discipline. You want your ad to reach the right audience. On the other hand, a GunBroker.com auction will have tens of thousands of potential buyers. Realistically, however, if you price your rig attractively, it should sell quickly in a Forum Classified Advert. Plus with conventional Classifieds, you can sell immediately — you don’t have to wait for the auction to end. For scopes and reloading equipment (but not firearms, actions, barrels etc.), also consider eBay, which still allows many gun-related items.
Editor’s Comment: All long-range competitive shooters should watch this excellent video — whether you shoot with a team or as an individual. Three cameras were used so you can watch the shooter, the range flags, and the target simultaneously. After a discussion of scoring, the actual shooting starts at the five-minute mark in the video. Under the guidance of wind coach Gary Rasmussen, U.S. F-Class Open Team Captain Shiraz Balolia shoots 100-7X for ten shots, following Gary’s wind calls.
Team Shooting with a Coach Shiraz tells us: “We come across a lot of shooters who have never shot under a coach. This video was produced to give shooters a basic understanding of shooting with a coach and the importance of releasing a good shot. In a team setting, you basically leave all the decision-making to the coach and aim where you’re told to aim. I’ve worked with Gary many times and it shows in the comfort level we have with each other. The coach plots the shots or a plotter advises the coach of any grouping that is not centered.”
Watch Gary Call the Wind and Shiraz Shoot 100-7X for Ten Shots
For best viewing, click the YouTube settings button to watch in 720p or 1080p HD (high definition).
Shiraz was shooting a 7mm F-Open rig: “My .284 Shehane rifle takes about 10 to 12 shots to settle down and that is probably why we made several scope adjustments while shooting. It is a great caliber and a step up from a straight .284 Winchester. The wind was relatively calm, but sometimes that slow wind with subtle angle changes can be very deceiving.”
The video was shot the first week of May 2013 at a range in Custer, WA located about 20 miles from Bellingham, Washington. The production team included Shiraz Balolia, Gary Rasmussen, three cameramen, and a target puller. Big Thanks to Grizzly Industrial for providing the camera crew and post-production talent.
Report based on story by Kyle Jillson inNRABlog.
There will be a new rifle discipline at Camp Perry this year — the NRA National Mid-Range Championships, slated for August 5-9. Created due to the rising popularity of F-Class shooting, the new 3000-point Mid-Range Championships will be shot from distances of 300, 500, and 600 yards and will add yet another fun sport to the annual Remington/NRA National Rifle and Pistol Championships. The new Mid-Range Championship isn’t just for F-Class Open and T/R rifles though. Sling shooters are allowed to compete with Service Rifles and Match Rifles and will be classified accordingly.
F-Class Basics
F-Class is target shooting with scoped sights and artificial support (bipods for F-TR and rests or bipods for F-Open). F-Class shooting is done entirely from the prone position. Originally started among older High Power shooters who were straining to see traditional iron sights and needed a little more support, the sport now includes young shooters as well as experienced shooters looking for a new challenge.
There are two F-Class divisions: Open Class (F-Open) and Target Rifle (F-TR). In F-Open, rifles can weigh up to 22 pounds, fire any caliber under .35 and may be shot off just about any type of rest. F-TR rigs are limited to 18.15 lbs (8.25 kg), must be shot off a bipod, and must be chambered for either the .223 Rem and .308 Win (or 7.62×51) cartridges. For F-TR, the bipods are counted in the weight of the rifle. Other F-class rules are found in the official NRA High Power Rulebook.
The Mid-Range Championships will be held alongside the High Power Rifle Championships August 5-9 at Camp Perry, Ohio. And if your thirst for F-Class has not been sated by then, the US F-Class National Championships are coming to the NRA Whittington Center in Raton, New Mexico from August 18-20. After that the Whittington Center will hold the F-Class World Championships from August 23-27.
The CMP has just released a new DVD: Basic Rifle Marksmanship. The DVD features a series of lessons taught by leading instructors from the U.S. Army Marksmanship Unit (USAMU). Aimed at prone, high power, and service rifle shooters, this new DVD covers the fundamentals of target shooting (with a strong emphasis on position shooting with sling and irons). This $6.95 DVD (#784DVDBRM) is offered through the CMP eStore. Content is divided into eight lessons:
If you want to learn how to shoot accurately at very long range, one of the very best places to learn is the Williamsport 1000-Yard Benchrest School. The 6th Annual Benchrest School will be held Saturday June 8 and Sunday June 9, 2013. There are still a few slots available for this year’s session. Classes, taught by top 1K shooters, are held at the Original Pennsylvania 1000-Yard Benchrest Club Range, one of the best 1K ranges in the country. View the range on the Williamsport website, PA1000yard.com
Prospective students will be taught all aspects of long-range benchrest shooting from some of the most skilled marksmen in the country. All areas are covered: load development, precision reloading, bench skills, and target analysis. Much time is spent at the loading bench and on the firing line. And you don’t even need guns and ammo — all equipment and ammunition will be provided.
School instructors tell us: “This year’s benchrest school will be a 2-day weekend event. (There is also a ‘Meet and Greet’ gathering Friday evening). The school is a beginner class designed to teach the fundamental skills needed to be competitive at at 600 and 1000 yards. Saturday will be spent in class covering a range of topics including reloading dos and don’ts, load development and equipment handling. Sunday we will shoot an actual match to see what you’ve learned.”
Don’t hesitate if you want to grab one of the remaining slots for the 2013 school. Contact the school directors right away. For more info, visit contact Dave Gardner (Public Relations) at pa1000br@yahoo.com or 570-916-9095. To get an application, please contact Nancy Miller (Club Secretary) at nancymiller@htva.net or 607-426-1535. Cost for the class is $300.00 including lunch and dinner on Saturday.
To see what the 1K Benchrest school is like, watch the slide show/video below, produced by Sebastian Reist, an alumnus of the 2009 Williamsport 1000-yard BR school. Sebastian, a talented professional photographer, captured the highlights of his Williamsport 1K training weekend:
This past weekend, Team Glock Captain KC Eusebio won the 2013 European Steel Challenge in record time. Held in Winterswijk, Netherlands, the Euro-Steel competition was hosted by the Stichting Winterswijkse Accomodatie Sportschieten. Eusebio shot the 6-stage indoor Open match in 58.57 seconds, winning by 3.07 seconds over two-time past European Steel Challenge champion, Saul Kirsch. This match was shot entirely indoors under artificial lighting. Eusebio used as GLOCK 34 pistol prepared by ZEV Technology.
Watch KC Shoot the Euro Steel Challenge
“I have always wanted to shoot this match against Europe’s best shooters on their turf,” said KC. “It was an honor to finally be able to do so. I can’t wait to come back to this beautiful country next year!”
After winning the Euro Steel Challenge, KC attended the Dutch Army MOD match (Harskamp, Netherlands) on May 15-16 as guest of the Dutch Army Shooting Team (photo below):
Eusebio Won U.S. National Steel Challenge in Florida in March
KC’s victory in Europe followed his win at the 2013 U.S. National Steel Championship on March 23, 2013 in Titusville, Florida. Eusebio shot the match in 76.27 seconds, setting a new Main Match record. KC beat his next closest competitor, Max Michel, by almost three seconds. KC’s 2013 time broke the previous record of 80.09 Eusebio set back in 2007. In Florida, KC won four of the eight stages outright, and he set two new stage records.
Report by Jeff Stover, IBS President
This past weekend, forty-five shooters from nine states descended on a piece of paradise in central Pennsylvania to try to shoot small groups at 100 and 200 yards. The 27th Annual Boop Memorial shoot proved to be a study in contrasts. Saturday was a good day for shooting. Sunday was brutal. On Saturday, small groups were “in”. Temps were in the mid 60s with on and off showers and humidity well beyond the clammy side. The winds were relatively light, and readable for the most part. But by mid-afternoon on Saturday, the humidity was dropping, the zephyrs growing stronger and the groups a just a bit larger. That was a portent for the tough conditions on Sunday.
Sunday was a beautiful spring day but a shooter’s nightmare with red and green wind indicators showing.
J.D. Denoff Shines on Saturday
The 100-yard stage was a J.D. Denoff show. The Virginia-based bullet-maker had his ‘A’ game going full tilt. He started by winning the Light Varmint 100-yard stage with a .2168 aggregate. Larry Costa had the same aggregate, but J.D. had the edge via tie-breaker. J.D.’s first three groups in the Heavy Varmint stage were three .140s and tiny .057. So, after four targets J.D. had a fantastic .1230 aggregate. If he could maintain that level a new IBS record was possible. J.D.’s shot at a record all depended on what he could do with his last target.
The weather gods did not cooperate. Conditions deteriorated, and J.D. only managed a .309 for his last target. That .309 looked huge compared to the tiny groups he had shot four times in a row. Still, he managed to complete a .1586 100-yard aggregate — still superb in anyone’s book. J.D. was shooting his own bullets (of course) crafted on Sierra jackets. He was running a new Bartlein barrel that he chambered himself. Smiley Hensley and Larry Costa, despite shooting ‘teen aggs’, were pretty far back with high .19xx scores.
Tough Conditions on Sunday
Sunday was a new day in more ways than one. The range at Weikert is known for sometimes wild and woolly conditions. Yes, there are some ranges with stronger winds. And there are others with those sneaky conditions that bite the unwary benchrester in the butt. But on Sunday, the conditions in the Penns Creek valley were downright tough, even for seasoned veterans. The fresh, dry breezes could not decide which way to blow. It was a war of the wills between green and red (wind indicator colors), with each struggling for supremacy.
The wind moved rapidly from 3 o’clock to 9 o’clock directions. The swing was so quick that checking the sighter was pretty much a waste of components. The only thing that resembled something to shoot was a dead tail wind. Yep, a tail wind was the only way to get something to resemble a decent group. Caution to the shooter, though, that ignored a teeny bit of red or green in your favored tailwind. Choosing both on the same target resulted in shots on either side of the one inch mothball (ten ring). One shooter, just for fun, shot the two extremes on his sighter and found nearly six inches of condition!
So given these conditions, many shooters, some of the best in the country were thrilled with a .6 or .7 group. It was one of those days when you shoot an inch group, you move up in the standings. So enter Larry Costa from Florida. Certainly, he is one of the best in the game. Like a lot of the knowledgeable shooters, he shot the tail wind, but he deftly holds for small changes in the wind’s direction.
Larry Costa won both Grand Aggregates and the Two-Gun overall.
Larry really dominated the match on Sunday. In the morning he shot a .2881 aggregate which was phenomenal for the day. He was followed by a top shooter, Hal Drake, with a .3310. Curtis Nelson shot his 30BR to third place with a .3806. The fifth place shooter, Bob Hamister, was over .4. Larry even shot a .177” small group just to add some zing into his win. If anything, the wind in the afternoon was bit worse. Larry won the LV 200-yard stage with a .3422 agg. Russ Boop was second with a .3759 and Hal Drake third with a .3773. With his two 200-yard wins, Larry Costa won both Grand Aggregates and the Two-Gun overall. In the Two-Gun he was followed by Russ Boop and J.D. Denoff.
IBS President Jeff Stover Talks About the 27th Annual Boop Memorial Shoot
[haiku url=”http://accurateshooter.net/Video/jeffstoveraudio2.mp3″ title=”Jeff Stover Talks about IBS”]Click “Play” to Hear Audio
Weikert Range on a damp early Saturday morning.
The Annual Boop Memorial Match honors the memories of Nate Boop and Rich Altemus. Both were “founding fathers” of benchrest shooting at the Union County Sportsmen’s Club in Weikert, Pennsylvania. Russ and Dale Boop are Nate’s sons. Awards at this year’s 27th Annual match were given by Nate’s grand-daughter Rachel (photo at right). Rachel is Dale Boop’s daughter.
Thus far in 2013, the National Shooting Sports Foundation (NSSF) has distributed 31,000 firearm safety kits through Project ChildSafe. Through this program, NSSF helps prevent unauthorized access to firearms when they aren’t in use. The NSSF launched Project ChildSafe in 2003 to educate gun owners on their responsibility to keep their guns out of the wrong hands, and provide the tools to help them do so.
Through partnerships with law enforcement the NSSF have distributed more than 36 million free firearm safety kits to gun owners throughout the United States. Notably, between 2000 and 2010, fatal firearm accidents dropped 22 percent. Firearms accidents are now less than 1 percent of all fatal accidents in the United States.
Message from Steve Sanetti, NSSF President
This year NSSF has committed $1 million to provide free gun safety kits, including a lock, in partnership with law enforcement agencies across the country, to gun owners, and educate gun owners about responsible firearm handling and storage. Success with this campaign relies on the participation of responsible firearm owners at the local level.
It only takes a few seconds for an accident to happen, and it takes just as few seconds to prevent one. Please join us in this important work.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
Many readers will be driving across multiple states this summer to attend competitions. Other shooters will be heading out of state for a game hunt or prairie dog safari. For $13.95 you can purchase a state-by-state 
The Traveler’s Guide to the Firearm Laws of the Fifty States has sold more than 950,000 copies since it was first released in 1996. The book’s author, Attorney J. Scott Kappas, has written numerous magazine articles and has appeared on television, explaining the unexpected pitfalls that shooters may encounter when traveling with firearms. Along with being an attorney, Mr. Kappas serves as a director on the Board of the Kentucky Firearms Foundation, and Kappas is a Class III firearms dealer.
These days, online gun auctions are busier than ever. Many folks are purchasing arms for the first time, and sellers are enjoying good prices for their wares based on increased demand. Some people even think that guns may be a safer investment than real estate or bonds at this time. That’s questionable, but this Editor finds it ironic that most of his guns have held their value while the 
For benchrest, F-Class, Silhouette, Tactical or High Power rifles, you may get the best results posting a For Sale ad on a Forum that caters to the right discipline. You want your ad to reach the right audience. On the other hand, a GunBroker.com auction will have tens of thousands of potential buyers. Realistically, however, if you price your rig attractively, it should sell quickly in a Forum Classified Advert. Plus with conventional Classifieds, you can sell immediately — you don’t have to wait for the auction to end. For scopes and reloading equipment (but not firearms, actions, barrels etc.), also consider eBay, which still allows many gun-related items.
Shiraz tells us: “We come across a lot of shooters who have never shot under a coach. This video was produced to give shooters a basic understanding of shooting with a coach and the importance of releasing a good shot. In a team setting, you basically leave all the decision-making to the coach and aim where you’re told to aim. I’ve worked with Gary many times and it shows in the comfort level we have with each other. The coach plots the shots or a plotter advises the coach of any grouping that is not centered.”
The CMP has just released a new DVD: 
If you want to learn how to shoot accurately at very long range, one of the very best places to learn is the 
This past weekend, Team Glock Captain KC Eusebio won the 2013 European Steel Challenge in record time. Held in Winterswijk, Netherlands, the Euro-Steel competition was hosted by the Stichting Winterswijkse Accomodatie Sportschieten. Eusebio shot the 6-stage indoor Open match in 58.57 seconds, winning by 3.07 seconds over two-time past European Steel Challenge champion, Saul Kirsch. This match was shot entirely indoors under artificial lighting. Eusebio used as GLOCK 34 pistol prepared by ZEV Technology.
J.D. Denoff Shines on Saturday
The Annual Boop Memorial Match honors the memories of Nate Boop and Rich Altemus. Both were “founding fathers” of benchrest shooting at the Union County Sportsmen’s Club in Weikert, Pennsylvania. Russ and Dale Boop are Nate’s sons. Awards at this year’s 27th Annual match were given by Nate’s grand-daughter Rachel (photo at right). Rachel is Dale Boop’s daughter.
Thus far in 2013, the National Shooting Sports Foundation (NSSF) has distributed 31,000 firearm safety kits through 
