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How to Handle Squib Loads and Hangfires
Jul 25th, 2014 by RoundsReloaded

How to Handle Squib Loads and Hangfires

The gun went bang…sort of. You know something’s not right, and you know you need to fix it safely. But how?

 

In our last discussion about handguns doing the unexpected, we discussed what some call the “loudest sound you’ll ever hear,” the dreaded “CLICK” when you’re expecting a “BANG.” But what about when your handgun goes “…bang…sort of?”  When something didn’t quite sound, or feel, right? If you hear a lighter-than-normal “bang,” and/or feel lighter-than-normal recoil, it’s possible that a “squib load” may have entered your ammo supply.

Though it’s extremely rare, a squib load/round is one whose propelling energy is less than necessary to push the projectile out of the firearm. This results in your handgun bullet being lodged somewhere between the chamber and the muzzle—a condition that could cause you major problems if you keep shooting. That’s because firing another round behind the squib might result in that following round— and the gases propelling it—getting stuck behind the lodged bullet. Consequences range from a mortally damaged handgun to a very seriously injured shooter.

While squibs are usually attributed to faulty powder charges,which in turn are attributed to careless reloaders, they can happen with any ammunition. I’ve seen high-quality factory ammo yield a squib or two. Still, squib rounds are rare, and in my career—having seen hundreds of thousands of rounds fired—I’ve witnessed five among handgun loads (three were reloads, two were factory ammo).

To safely and properly “fix” a squib load situation, first pay attention when you’re shooting! As soon as you noticed any difference in the sound or feel of a shot, stop. Unload the firearm. Then disassemble it, if possible, and examine the barrel by looking through it (for a revolver, drop a weighted string through the forcing cone and see if it comes through the muzzle). If there’s an obstruction, take a properly sized wooden dowel (it should be close to the diameter of the bore, but should move freely in the barrel), and place it through the muzzle or chamber end to determine where the stuck projectile is located in the bore. Then, take the dowel through the end of the barrel that’s furthest from the projectile, and gently tap the bullet out from the closest end of the barrel to it.

Even rarer, but potentially more dangerous if proper safety rules aren’t observed, is the “hangfire.” A hangfire is defined as a delay in the detonation of the propellant (gunpowder), which in turn results in a delay in the firing of the cartridge. The delay can be as long as seconds, but is often almost undetectable. It’s evidenced by a “click,” instead of a bang, but can also occur when you hear a much-lighter-than-normal sound upon on the firing of your handgun. Like squib loads, hangfires are often blamed on sloppy reloading habits, but can occur amongst any type of ammunition, including factory manufactured rounds.

The safest way to get past a hangfire is to keep your muzzle pointed on target (safe direction), wait for several seconds, and execute your “tap-rack-roll” move. How long do you wait? Opinions vary widely, and I’ve heard everything from five to 60 seconds prescribed. Then, there are those who insist that you should not wait, and should go ahead and conduct the “tap-rack-roll” action to clear the bad round and chamber a new one. The latter group (to which I belong) generally bases this advice on the ideas that:

A) If training for self-defense, waiting to reload the chamber could be far more dangerous than extracting the bad round, even if it detonates.

B) If the cartridge does eventually “go off,” but is outside the firearm, the chances of injury are minimal.

C) If the round is a hangfire, it’s impossible to know when it will detonate—or how long to wait. And, see item B).

Regardless of how long you wait to clear the cartridge, following the Four Safety Rules in combination with your chosen method will keep you safe. Likewise, paying attention to what you’re sensing when shooting will help you identify a squib situation. Just keep in mind that firearms, and ammunition, are man-made, mechanical products, and rare as it is, they can malfunction. The good news is, once you understand the malfunctions, you’ll see that you have the power to manage many of them, and above all, to stay safe while doing so.

Beretta Moves All Manufacturing Out of Maryland
Jul 25th, 2014 by RoundsReloaded

Beretta Moves All Manufacturing Out of Maryland

 

While Beretta already announced in late January that it would expand its future manufacturing operations at its new Gallatin, Tenn., facility due to Maryland’s oppressive gun laws, things heated up today with the announcement that all manufacturing will now move to the far-more-firearm-friendly state of Tennessee. (Read the official press release here.)

Founded in Gardonne, Italy, in 1526, Beretta is not only the world’s oldest firearms manufacturer, but the family-held company is the oldest continuous maker of anything. Cavaliere Ugo Gussali Beretta has written about his concerns about the future of firearm manufacturing in Maryland, but the move surprised both the firearm industry as well as Maryland media outlets today. At stake are 160 manufacturing jobs that have been a boon to Prince George’s County. Maryland’s loss is Tennessee’s gain.

All manufacturing, which includes the standard sidearm of the U.S. military, the 9×19 mm U.S. M9, which still has active contracts, will move to Tennessee. Beretta is not completely abandoning the “Old Line State,” though, as it is said the company headquarters and some gunsmithing and repair operations will remain in Accokeek, Md.

While awaiting official word from Beretta, which we will follow up on tomorrow, the consequences of the anti-gun legislation passed last year and the current governor’s fascination with additional gun control in the state are clear. Not only did the company choose not to expand in the state, but now the jobs that have been there since the 1980s are moving to a far less hostile climate. We will have more as the story continues to develop.

Lack of Concentricity
Jul 18th, 2014 by RoundsReloaded

Lack of Concentricity

Written by Sierra Ballistic Technician Rich Machholz

I have had this experience personally and stumbled across one solution quite accidentally.  Of course there could be several things causing this, so we can explore this one by one.

If your neck is .001″ out before seating a bullet that will be amplified if measured on the bullet after seating.

The solution may be as simple as polishing the upper edge of the expander ball.  Both the seating die AND the sizing die need to be squared to a dedicated shellholder in a dedicated press.

This is not normally an everyday chore, but check it every time by raising the shell holder to the bottom of the die to a light touch and watch to be sure that more than just one side touches.  A light behind the press will help and if just one side does touch, resquare the dies.

If you find a true straight loaded cartridge use it to square the seating die as a quick fix by backing the seating die off and running the ram to the top of the stroke.  Now back your seating stem off to make sure you don’t disturb the original seating depth and screw the die body down until it contacts the crimping ledge in the seating die and back off a half turn.

Set the seating stem snugly against the bullet and tighten the lock ring.  Next tighten up and set the lock ring on the die body and you now have a quick fix.

A GOOD and UNIFORM inside champ here can solve a lot of seating problems, concentricity or lack thereof being one of them.

You can use the deep hole provision of your calipers to check the height of your shellholder as mounted in the ram and the ram itself for squareness.

Or … you can invest in a Forster Co-Ax press and benchrest dies and kiss concentricity issues good bye.  Or find a press that IS square.

Fighting concentricity is very frustrating and to think we didn’t even worry about it 20 years ago, maybe even less than that, but that is also the reason today’s rifles are so outstandingly accurate.

I hope you find the cure to your problem and good luck.

Army to replace 9mm pistol
Jul 13th, 2014 by RoundsReloaded

Army to replace 9mm pistol with more reliable gun packing better ‘knock down’ power

 
FILE: 2007: A U.S. army instructor fires with Colombian soldiers during a combat exercise in a southern Colombian. REUTERS

FILE: 2007: A U.S. army instructor fires with Colombian soldiers during a combat exercise in a southern Colombian. REUTERS

The Army wants to retire its supply of 9mm handguns and replace it with a more accurate and user-friendly model that also will provide soldiers with more “knock-down” power.

Army officials say their inventory of more than 200,000 semi-automatic Beretta M9 and Sig Sauer M11 pistols has become outdated, worn out and needs to be replaced with an updated model that also offers more reliability and durability.

 They also are considering new ammunition, which has sparked considerable debate among military and civilian weapons experts, too. 

“Advancements in firearms have taken place since the M9 was adopted nearly 30 years ago, and it is our intent to take advantage of these advancements,” a military spokesperson told FoxNews.com on Friday. “The Army is seeking to replace the M9 and M11 pistols with a handgun that is more accurate, ergonomic, reliable and durable than the current pistol.”

Officials seem opposed to an update version of the Beretta M9, despite the company offering to make changes.

“We have submitted numerous changes or product improvements that really address a lot of the shortcomings that are either perceived or real,” Beretta development manager Gabe Bailey recently told Military.com.

The Army has been considering a change for several years and on July 29 will hold a so-called “industry day” to brief gun manufacturers about the competition requirements for a winning proposal.

The Defense Department will reportedly buy more than 400,000 new pistols if and when officials agree on a new model.

Beyond the 9mm’s durability issues, which Army officials says are costing them too much in repairs, soldiers also say the pistol needs a more ergonomic grip, its safety device too often locks inadvertently and its open-slide bullet chamber allows in too much dirty, which results in jamming.

Still, the other big issue appears to be about the caliber of the new ammunition, considering most experts argue a person must be hit with several 9 mm rounds to be killed. 

“We are not dictating a caliber during the competition,” the spokesperson said. “A vendor may submit multiple calibers of ammunition. However, the ammunition must exceed the performance of the current M882 9mm round.”

Among those likely to be considered in the Modular Handgun System competition are the .40 and .45 caliber rounds.

The argument against the .40 caliber round is that its heavier weight and stronger recoil causes excessive wear on a 9 mm pistol.

There have been no reports on how much the new weapons will cost, amid budget concerns. However, in September 2012, Beretta received a 5-year, $64 million firm-fixed-price contract for up to 100,000 of its M9 9mm pistols, according to Defense Industry Daily.

Following industry day, the Army will release a draft Request for Proposal, which seeks input from manufacturers.

The Army will then consider the manufacturers’ comments and modify the request, if necessary. It will then hold a final industry day before issuing a final proposal before the end of the year.

The next phase will essentially be a tryout and elimination process, which officials say will be based on technical results and will rely “heavily” on soldier feedback.

“One of the primary requirements for this weapon system is to provide the soldier with increased terminal performance,” the spokesperson said. “Feedback from soldiers in the field is that they want increased ‘knock-down power.’ And the MHS program will evaluate commercially available weapons that meet that requirement.”

The Myth: The .223 is too Light for Deer
Jul 11th, 2014 by RoundsReloaded

The Myth
The .223 is too light for deer.

The Facts
I read somewhere that today’s premium bullets represent the greatest advance in big game hunting technology since the widespread use of the optical sight, and I agree 100 percent. Many of the myths that we face today are the product of outdated truth—what your grandfather or Elmer Keith said 50 years ago may not be true today. The fact is that today’s premium bullets penetrate deeper, expand more reliably and stay together better than ever before. This has been a game-changer for small calibers (note the resurgence in the .243 Winchester). It’s not that the laws of physics or reason no longer apply, but the fact is that bullet technology has readjusted the scale of which calibers are appropriate for what game. Thanks to these advances, .224 caliber bullets are no longer designed with either varmints or Soviet infantry in-mind. Let’s take a look at factory ammo.

Federal Premium alone lists four factory loads appropriate for deer-sized game, I’m not talking FMJ behind the ear appropriate either—these are legitimate, put-it-on-the-shoulder big game bullets. All of these bullets should shoot well without the need of the fast-twist barrels necessary for the longer, heavier (and excellent) .224 bullets on the market. I’ve personally used three of these bullets in various loads on management whitetails and a truckload of feral hogs—none of them lived to tell about it.

I asked around for some opinions based on more than anecdotal experience. As always, I found a public relations professional willing to answer some questions.

“We would agree that there are adequate loads/bullets for humanely taking deer with the .223,” said Tim Brandt, Federal Premium Public Relations Manager. “We have several .223 loads featuring a couple different bullet options that are designed especially for hunting. Our Fusion line is great example. We see excellent weight retention, expansion and penetration from this bullet in the .223 platform. Hunters that live in areas where it’s legal to use this caliber should have no problem finding an effective load to take into the deer stand.”

Tim also included the following test data, which shows that the average Fusion bullet penetrated nearly 15 inches of gelatin and expanded to .54 caliber. Most of a bullet’s expansion happens within the first inch or so of penetration which means that the Fusion load effectively sends a .54 caliber ball through the vitals of its intended target. I observed recent tests of the DoubleTap load with similar results.

Gelletin

Federal Fusion Rem. bullet fired into 10 percent ballistic gelatin at 100 yards (bullet expanded and penetrated to 15 inches)

Bullet

Five Federal Fusion .223 Rem. bullet expansions shot into 10 percent bare gelatin

One of NRA’s contracted experts, Richard Mann, helped develop the Bullet Test tube. (It’s slightly harder material than the gelatin used in Federal’s test.) Mann tested Federal’s loads in it and on deer, and here’s what he found:

“The .223 Remington is a suitable cartridge for hunting deer, within its limitation. This cartridge relies on velocity to drive the lightweight bullets deep. This same velocity contributes to tissue damage. The key to using a .223 Remington on deer is to keep impact velocities high. In other words don’t shoot deer much beyond 150 yards. Past that distance, the velocity drops below the level needed for dynamic bullet expansion. When robustly constructed bullets like the Barnes TSX, Nosler Partition and Fusion are used inside 150 yards, penetration with the .223 Remington is on par with cartridges like the .243 and the .30-30 Winchester.”

Ok, so we heard from the nerds in the lab coats, what do the guys that shoot deer for a living think? My friend John Shaw has killed more deer than anyone I know—he’s managed an exotic game farm, worked on a Texas whitetail ranch, passionately hunts whitetail in numerous states using the .224 and .22-250. He has also culled scores of does for meat, depredation, and management purposes. John has this to say:

“I rely on my 22 centerfires more so than any other caliber. Low recoil and the typical pinpoint accuracy found in rifles of .224 caliber allow for careful shot placement. If you treat hunting with your .223 much like bow hunting and wait for the perfect shot, there is no reason that this caliber should not be considered for many applications. However, bullet choice is a major factor. Shots to the central nervous system with any type of bullet will work but I recommend premium, controlled expansion bullets, such as Barnes Triple Shocks, Nosler Partitions, and Trophy Bonded Bear Claws. Typically, I keep shots under 200 yards but animals hit in the shoulder, heart, and lung region with a quality bullet expire quickly.”

The Conclusion
I’m not saying the .223 is the perfect whitetail bullet, I wouldn’t pack it on a trophy hunt or where long shots were likely but, with the right bullet, it is a legitimate choice for some big game animals. With big game bullets ranging in weight from 55gr. to 70gr., it’s versatile at a range of velocities.

Long Range Load Development
Jul 9th, 2014 by RoundsReloaded

This article was posted on Sierra’s Facebook page. We found it to be very interesting; so much so that we thought it was worth to be posted in our blog as well. To all the precision long range loaders and the aspiring ones as well, enjoy it. We know that some of us will try this method out.

Long Range Load Development

Written by Sierra Bullets Product Development Manager Mark Walker

walker1

 

Since I just put a new barrel on my F-class rifle this spring, I figured it might be a good time to discuss load tuning for long range shooting. Getting the most accuracy out of your rifle is one of the most important aspects of load tuning. For long range shooting in particular, using a load that produces the least amount of vertical variation is vital. There are several steps to the process that I use, so I will go through the basics of each. When I first get a new barrel installed, I like to determine what the loaded cartridge “jam” length is. I do this by taking an empty case (no powder or primer) that has been neck sized with the proper bushing (I like to shoot for 0.002 smaller than the loaded cartridge neck diameter) and seat a bullet long in it so that the throat of the rifle will move the bullet back into the case when I close the bolt. I close the bolt several times until the bullet stops moving back into the case at which point I use a comparator with my calipers and get a length measurement on the cartridge. This is what I consider to be the “jam length” for this barrel and chamber. I came up with 3.477 as the “jam length” for this particular barrel. Next, I will fire form some brass using a starting load of powder and bullets seated to “jam” while breaking in the barrel. My barrel break in process is not very technical; it’s mostly just to get the brass formed and the rifle sighted in. I do clean every 5 rounds or so just because I feel like I have to. Once I have the brass formed, I use them to load for a “ladder “ test to see what powder charge the rifle likes. With a ladder test, you take your starting load and load one round each with a slightly increasing amount of powder until you reach your max load for that cartridge. You then fire each round using the same aiming point to see where the bullets start to form a group. For this barrel and cartridge, I started at 53.3 grains of H4831SC powder and increased the load by 0.3 grains until I reached 55.7 grains. I always seat my bullets to “jam” when doing a ladder test. We will determine the final seating depth in another test later. It’s usually best to shoot this test at a minimum of 200 yards because at closer ranges the bullets will impact too close together making it hard to determine which load works best. I shot this test at 300 yards.

walker2072-copy

 

As you can see from the target, the lightest load #1 had the lowest velocity and impacted lowest on the target. Shots #2 and #3 were a little higher and in the same hole. Shots #4 thru #6 were slightly higher yet and all had the same elevation. Shots #7 and #8 were the highest on the target however pressure signs were starting to show. For some reason shot #9 went back into the group and the chronograph didn’t get a reading so I ignored that shot. When picking a load, I am looking for the most shots at the same vertical location on the target. As you can see that would be shots #4 through #6 so I would pick a powder charge from those shots which would be 54.2 grains to 54.8 grains. As a side note, shots #2 and #3 are only 0.851 lower so I wouldn’t be afraid of using one of those loads either. I settled on 54.5 grains as the load I wanted to use. It’s right in the middle of the group so if the velocity goes up or down slightly, the bullet should still hit in the same place on the target. Now that we’ve settled on a powder charge, I want to find the seating depth the rifle likes. I usually start at jam length and move the depth in 0.003 until I get to 0.015 deeper than jam. I load 3 rounds at each depth using the 54.5 grain powder charge and shoot a group with each depth at 150 yards. As you can see from the target, the first two groups are not good at all. Next one looks good and is the smallest group on the target. The next three are not quite as small but the vertical location on the target is almost the same which indicates a sweet spot which will help keep the vertical stringing to a minimum on target. I went with 3.470 which is right in the middle once again and should give some flexibility with the seating depth.

walker3074a

 

So after all of that, my load is 54.5 grains of H4831SC and a cartridge length of 3.470. I plan on loading up enough ammo to shoot five groups of five shots and see exactly how this load works on target as well as what the extreme velocity spreads are over several groups. I sincerely hope some of this information helps you to get the best accuracy out of your rifle. I do not take credit for coming up with any of this, a whole lot of good shooters use this same method or a variant of it when working up their loads. For more information about load development, please contact the Sierra Bullets technical support team at 1-800-223-8799 or by email at sierra@sierrabullets.com.

Disclaimer: Load data represented here may not be safe in your rifle.

 

Cartridge Crimp Styles and Uses
Jul 4th, 2014 by RoundsReloaded

Cartridge Crimp Styles and Uses

Lee 3-die set with taper crimp die.

Crimping, that final stage of handgun cartridge assembly. Whether done as a separate operation, or as a part of the bullet seating process, one simple fact remains – it must be done.

There are two distinct types of cartridge crimps: Roll crimping and taper crimping.

In the handgun world, it is a pretty clear distinction. Roll crimping is best used on the revolver cartridges, and taper crimping is the way to go for semi-automatic pistol cartridges. Here’s the why.

Cartridges designed for use in a revolver use some sort of a rim to properly headspace the case in the cylinder. Think .38 Special, .357 Magnum, .45 Colt, .44 Remington Magnum. This guaranteed headspacing allows the reloader to “roll” the case mouth around the cannelure of the bullet, ensuring that the bullet will not move during recoil. This also gives us a consistent overall length if you roll crimp on the cannelure.

I will note that a roll crimp should only be used with bullets that have a cannelure; if you try to roll crimp on a bullet without one, you risk bulging the case mouth, and it will not fit properly in the cylinder. We’ll get back to how to crimp a bullet with no cannelure for revolver use in a second.

The bullet seating die for most pistol cartridges can be adjusted to give a good, solid roll crimp. Read the die set instruction carefully, and follow the directions. It may take a few tries to get the proper crimp, and I usually make a dummy round, with no powder or primer, to use as a guide should the die come out of adjustment.

Those cartridges that work well in the semi-automatic pistols can’t be roll crimped, because those cartridges headspace on the case mouth rather than a rim, which most lack. You see, rimmed cartridges (generally speaking) don’t feed well from a pistol magazine, so the autoloaders usually employ a rimless design. Think .45 ACP, 9mm Luger, .40 S&W, .380 Automatic.

The rimless design needs to headspace on something other than the rim, of which there is none, and the lack of a shoulder (as in a rifle cartridge) leaves only the case mouth. If we were to roll crimp, we would compromise the squared case mouth for headspacing. Yet, we still need to hold the bullet firmly in the case.

40 Smith & Wesson ammo needs to be taper cripmed.

This is where the taper crimp method comes into play. It squeezes the sides of the case wall tightly against the bullet, and effectively prevents the bullet from moving, while maintaining the nice square case mouth that allows the cartridge to headspace.

A taper crimp can solve the problem I previously mentioned, where revolver cases use a bullet with no cannelure, yet need to be crimped. No bulged cases, no mess. Taper crimp and fire away!

Most companies that make quality reloading dies will have a taper crimp die available for purchase. If you’re serious about your pistol’s performance, I highly suggest you invest in one.

Stay crimpy, my friends.

 

Berger Article on COAL and Cartridge Base-to-Ogive – Part 2
Jul 2nd, 2014 by RoundsReloaded

Berger Article on COAL and Cartridge Base-to-Ogive – Part 2

litzcoal03Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2

by Bryan Litz for Berger 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.

litzcoal02

Figure 2

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.

Figure 4

Figure 4

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
Jul 1st, 2014 by RoundsReloaded

We found this article in the Berger Bullets website; it is an interesting and informative piece for reloaders seeking to improve accuracy. Remember that safety is achieved with knowledge.

 

Effects of Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO) – Part 1

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.  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 thru 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

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.

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.

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).

Figure 2. Chamber throat geometry showing the bullet jump to the rifling or lands.

Figure 2. Chamber throat geometry showing the bullet jump to the rifling or lands.

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.

Figure 3. Illustration of a bullet being seated out of the case too far to feed thru a magazine.

Figure 3. Illustration of a bullet being seated out of the case too far to feed thru a magazine.

Considerations for Magazine Feeding

When a hand loader is working to establish a seating depth to use with a particular bullet, he must decide if he needs the cartridges to feed thru a magazine or not.  If the shooting application is hunting or tactical shooting, then the shooter probably needs the rounds to cycle thru the magazine so the rifle can be used as a repeater.  However, in many slow fire target shooting applications, it’s not necessary to magazine feed the cartridges.

Often times when a shooter doesn’t need to feed rounds thru a magazine, the shooter can take advantage of substantial performance improvements by loading the bullets out long.  This brings up an important reality of seating depth and COAL.

 

SAAMI COAL Limits Ballistic Performance

It is a fact that the ballistic performance of modern ammunition is directly limited by the SAAMI COAL standards that are currently in place and that rifle manufacturers build to.  Even when a shooter understands the implications of cartridge case volume and has a chamber that allows them to load the rounds out long, the rifle itself (having been built to feed SAAMI length cartridges) won’t allow the shooter to do so.

This fact is one reason for the popularity of custom rifle builders who understand the importance of feeding longer than SAAMI length rounds and building rifles with long enough actions and magazines to cycle the rounds.  The first commercial rifle manufacturers who figure this out and start building rifles capable of feeding longer rounds will lead the way into modern times.  There have been many improvements to several key components of modern rifle ammunition, specifically bullets and powder.  It’s unfortunate that many rifle makers continue to adhere to the antiquated SAAMI limitations that were put in place so long ago when components were so different, standards which limit the performance of modern potential.

 Summary of COAL discussion

To recap the important considerations regarding bullet seating depth as it relates to COAL, we can say:

–  Seating a long bullet to the restrictive SAAMI COAL can severely decrease the internal volume of the cartridge which will limit the max velocity the cartridge can achieve.

–  If magazine feeding is not a requirement (or if you have a longer than standard magazine) you can load your bullets long, which increases the volume for powder and allows you to use more powder and achieve faster MV for the same pressure.

–  If you load the bullet too long and it encounters the lands, this can elevate pressure due to the engraving force resisting the bullets’ initial forward motion.

 

The second half of this article will discuss the differences between Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO), and why a working knowledge of both is beneficial to shooters and reloaders.

Bryan Litz

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