The Art and Science of Annealing
Annealing Basics, Cartridge Metallurgy, and Automated Options

For many reloaders, annealing is a "dark science" that defies easy explanation. When done right, annealing extends brass life and makes neck tension more consistent, something very important for accuracy. There is plenty of evidence that annealing works. Just look at your new Lapua brass--those rainbow colors on the necks are artifacts of annealing. And we know annealing can make your brass shoot better and last longer. Score Shooter of the Year Joe Entrekin has 40+ reloads on his regularly-annealed brass. The smallest 1000-yard 5-shot group ever shot in IBS competition was done with brass annealed after every firing. So, learning how to anneal the right way is something that can benefit every precision shooter. For this feature, IHMSA Champion Silhouette shooter Jim Harris and manufacturer Ken Light explain the "dos and don'ts" of annealing, clarify many common misconceptions, and review the best gear for both manual and automated annealing.

Ken Light BC 1000 Annealing Machine SPONSORS

by Jim Harris and Ken Light

Annealing--Basic Concepts
Annealing is a process wherein heat is applied to a metal in order to change its internal structure in such a way that the metal will become softer. Most of us think of "heat treating" when we think of applying heat to a metal in order to change its internal structural properties. The word "heat treating" is most commonly associated with steel. However, the term heat treating is not annealing, except in a general and journalistic sense of the word. Heat-treating refers to a process wherein the metal is made harder. Annealing always means to make the metal softer.

In order to make steel harder, it is heated to some temperature, and then cooled fairly rapidly, although this is not always the case. Brass, on the other hand, cannot be made harder by heating it--ever. Brass is always made softer by heating.

The only way brass can be made harder is to "work" it. That is, the brass must be bent, hammered, shaped or otherwise formed. Once it has been made hard, it can be returned to its "soft" state by annealing. The hardness of brass can be controlled by annealing for a specified time and temperature.


DeKort Annealing MachineAnnealing Video with Home-Built Carousel
Our Dutch friend Jim DeKort created this 2.5 minute video of his annealing machine in action, processing 6BR cases. This carousel unit, similar to Ken Light's BC 1000, was designed and built by Jim's father. Currently Jim leaves a gap between each shell to allow more "flame time" per case. But he will be adding a second torch soon and then he can have a case in each slot. The cartridges spin in their mounting holes while they are rotated clockwise by the shell wheel. Right-Click on Screenshot and "Save As" to download 2.8 megabyte Windows Media video. Or Right-Click this Movie Link.

Cartridge Case Annealing
"Properly" annealed cartridge cases are essential to maintaining accuracy and long case life when using hand-loaded ammunition. The question is, what is "properly" annealed? What does annealing do? Can a cartridge case be over annealed? What part of the case should be annealed? Can annealing a cartridge case make it dangerous? Below, you will find the answers to these questions, as well as a number of other questions that you didn't ask.

A great deal has been written about cartridge case annealing in the popular gun press. A great deal of what has been written about annealing is misleading, with one exception: articles and books by Dean A. Grennell. In his "The ABC's of Reloading" (page 190), Mr. Grennell correctly describes the procedure. Although it is a very short description, it is correct. There is one slight error of fact, but it is on the side of safety and Mr. Grennell cannot be faulted for this in any way. In fact, if you do not have this book I recommend it--even for "experienced" handloaders. There is much valuable information in it, much of it overlooked in other publications. The photo's are profuse and excellent, the explanation clear and concise, and the writing is witty and wry.


Few handloaders ever bother to anneal their brass. The few that do are usually dyed-in-the-wool "gun cranks" (to use a rather archaic term from the 1940's), "crazy experimenters" or shooters who are involved in some form of competitive shooting. There is good reason for this, too. Until now, annealing cartridge brass was, at best, a spotty proposition. The brass is either over-annealed, under-annealed, improperly annealed or some combination of all three. Annealing brass is time-consuming, and for the most part, the damn stuff doesn't seem to shoot any better than before it was annealed. Sure, the brass lasts longer, but it does not seem to make any improvements in accuracy. If anything, it might seem to open up groups. So much for the way you used to think about annealing.


Before I go into the whys and wherefores of cartridge brass and the right way to anneal, let's review the traditional methods of annealing, the attendant disaster, and how they occur.

The "Traditional Methods"--What Works and What Doesn't
The usual procedure is to get a pan, something like a cookie pan, and place enough water in the bottom of it to cover the lower one-third to one-half of the brass. Next the cartridges are stood on their bases in the water. A flame from a propane torch is played over the case necks until the brass "just begins to glow" or "just before it begins to glow". When the magic moment is reached, the annealing is abruptly arrested by knocking over the heated case into the water. The fact that the case neck is heated unevenly and the case-to-case heating is hardly uniform doesn't seem to get much notice.





Temp-Sensitive Markers for Annealers Tempil sells both temp sticks and brush-on temp-sensitive laquer. The crayon-like TempilStik leaves a coating on the neck that melts at the point of contact once the surface reaches the product's rated temperature. Tempil temp-sticks work well and are available in most plumbing supply stores. Liquid Tempilaq dries to dull, opaque film once applied. When you heat the necks, and the rated temperature is reached, the film liquefies. Tempilaq works, but we favor the temp sticks--application is faster and less messy, and the change at target temp seems easier to see. A 650°-rated marker is good for starters, but you may need to go higher or lower to get the best results.
TempilStik Temp Stick


Cartridge Cases and Precision Manufacturing




The Cartridge Case Inside The Gun
Actually, a cartridge case is the primary component with which we have to deal in hand-loading. Not only that, but it is the cartridge case which seals the chamber when the gun is fired. If it weren't for the amazing properties of the cartridge case, you would get a hot blast of gas in your face every time you pulled the trigger.


As the bullet speeds down the bore, the pressure begins to drop. Finally, the bullet clears the muzzle and the pressure abruptly drops to zero (in fact, to atmospheric pressure). The cartridge case, having done its job to seal the chamber, has more "work" to do. It must spring away from the chamber walls so it may be extracted. If it does not, it will be a b*tch to remove from the gun. If it fails to spring back from the chamber walls sufficiently, it will seem to be a little "sticky". If it does not spring back at all, it will take the hot hammers of hell to remove it.




Properties of Cartridge Cases
A finished cartridge case is made so that the hardness of the metal varies over its length. It must be "hard" in some places and "soft" in others. In order to make brass hard, it must be "worked" or, in a crude sense, "hammered".

Most metals "work harden" as they are formed, and brass is no different. The term "work" means that the fine granular structure of the metal is placed under stress and changes as a result of forming or shaping. These stresses remain in the metal in the form of changes to its grain structure. (This is somewhat oversimplified, but is accurate as far as it goes).

The metallic "grains" can actually be seen if the brass is etched in an acid solution and examined under a microscope with the proper lighting conditions--obviously a laboratory job, and not a subject which I will take up here. When the grains become too fine, the metal will easily crack. However, there are ways to discern the general condition of the metals structure without a laboratory examination.

The cartridge case, as it comes from the factory, is not one single hardness over its entire length. The neck, which must hold the bullet in place with sufficient holding power to prevent its setback while undergoing recoil (as it is stored in a magazine or clip), is somewhat "soft" compared to the head of the case.

By "soft" I do not mean to imply that it is like "dough" or soft like an aluminum beer can. It is "soft" only in comparison to the head of the case. On the other hand, the head of the case is not "hard" like a ball bearing is hard--it is only "hard" enough to do its job and no more. If it is too hard or soft, in the wrong places, the cartridge case will fail, and your first indication of this disaster may be a cloud of gun parts flying in into your face. Such a rapid disassembly of a gun is usually attributed to "an overloaded cartridge," but just as well be from a normally loaded cartridge (developing normal pressures) whose case failed rather catastrophically, and, I might add, rather suddenly, because it had lost its necessary properties.

How hard is "hard", and how "soft" is "soft"? It is not a question which is easily answered, and I will waffle a bit during the explanation. Normally you will use a cartridge case until it is no longer serviceable because of two main reasons: the case necks will become too thin from repeated sizing and trimming operations, or the necks start splitting. In the first case, you will probably detect the thinning by simply looking at the case necks. Your experience will tell you that they are not "right" and that it is time to get a new batch of brass. In the second case, you will spot the split necks as soon as they are extracted from the gun, or possibly during some inspection step during reloading.



rcbs rockchuckerCase-neck thinning occurs when the cases are repeatedly resized. Each time the case is run into the sizing die, it is squeezed back to its original dimensions--moved from one dimension to a smaller one. As the brass is squeezed back to its original dimensions, it's work hardened even more. Each trip through the chamber and resizing die adds to the work hardening of the necks. The usual method of correcting this is to anneal the case necks only.

You might assume that brass is brass and that a little heat can't possibly hurt anything. After all, the heat in the chamber is actually hot enough to melt steel, isn't it? Yes, it is. But, the "fire" and attendant heat are of such short duration that the brass is virtually unaffected. In order to change the grain structure, TIME (as well as temperature) is critical. After too much heat and/or too much time, the brass will be over-annealed. It will be too soft, and the entire case will be affected.

Optimal Case Temperatures for Successful Annealing
Brass is an excellent conductor of heat. A flame applied at any point on a case for a short time will cause the rest of the case to heat very quickly. There are several temperatures at which brass is affected. Also, the time the brass remains at a given temperature will have an effect. Brass which has been "work hardened" (sometimes referred to as "cold worked") is unaffected by temperatures (Fahrenheit) up to 482 degrees (F) regardless of the time it is left at this temperature. At about 495 degrees (F) some changes in grain structure begins to occur, although the brass remains about as hard as before--it would take a laboratory analysis to see the changes that take place at this temperature.


If cases are heated to about 600 degrees (F) for one hour, they will be thoroughly annealed--head and body included. That is, they will be ruined. (For a temperature comparison, pure lead melts at 621.3 degrees F).


Brass will begin to glow a faint orange at about 950 degrees (F). Even if the heating is stopped at a couple of hundred degrees below this temperature, the damage has been done--it will be too soft. From this discussion we can see that there are four considerations concerning time and temperature:






Ken Light BC 1000 Anneal MachineAutomated Annealing

1. Control the time the case neck will be heated.




Add to the above list the additional frills listed below, and you'll be in hog heaven:

5. The annealer must be easy to set up.

6. The annealer must be simple and easy to maintain.

7. The process must be "dry"--that is, the brass should not become wet and have to be dried before reloading.




Over-Annealing and Under-Annealing


Any annealing whatsoever of the cartridge base is over-annealing and is dangerous. This area of the brass must retain the properties it had when it left the factory. If it is made the least bit softer, let alone "dead" soft, the stage is set for another shooter's nightmare. At the very least, you may get a whiff of hot gas directed toward your face. At the worst, you can be seriously injured as your gun behaves more like a hand grenade than a firearm.

I once heard a tale of a gentleman who placed his brass on a cookie tray and placed the whole batch in an oven at 650 degrees for over an hour. He wasn't hurt--at least seriously. His attitude toward annealing is very negative.


Testing Cartridge Brass for Hardness and Softness

Place one of the used cases base down in a shallow tray containing water up to the lower third of the case, and deliberately over-heat the case neck--bring it to a red heat.





Now, squeeze the annealed case. The pressure to deform it is markedly less and when it is released, the case mouth remains deformed--no spring.

One more test--stand the annealed case on a metal plate (no water over the base) and heat the upper half to a red heat. Hold the heat for a few seconds and then let it cool. Adjust the Vice-Grips so that they can put considerable squeeze on the head area and crush the annealed case. Now crush one of the normal used cases. The difference is dramatic. Don't test an over-annealed case in a gun just to see what happens--take my word for it, the results can be dangerous to life, limb and eye, not to mention the condition of the gun. Finally, crush all test cases so that they won't get mixed in with good brass.


Preparing the Brass for Annealing


Working with the BC 1000 Automatic Case Annealer

Ken Light Anneal BC 1000 Annealing MachineThe BC 1000 is an automated, carousel annealing machine that can process 1000 cases per hour. Sold by Ken Light Manufacturing, it retails for $325, with a single shell-holder ring ("shell wheel"), but without propane tanks or burner tips. Shell wheels come in four thickness: 0.5", 0.75", 1.0", and 2&;quot; (for 50BMG). Extra rings up to 1" thick cost $42. For a 6PPC or 6BR, the three-quarter inch thickness shell wheel is recommended. Before we go any farther in describing the operation of the BC 1000, please heed this warning:




On a bottle-neck rifle case, the central portion of the flame should be on the case neck, and the outer portions of the flame will "wash" over the shoulder and down the side of the case for a short distance. As the cartridge goes around the wheel, it will turn, causing the entire periphery of the neck to be exposed to the direct flame at one time or another.

With this setup, the neck will actually reach a temperature between 750 and 800 degrees. Remember, it's the combination of time AND temperature that does the job. We have raised the temperature sufficiently to be able to anneal the case necks in 6 to 8 seconds.


As the case progresses through the flame, watch it closely. You will detect a slight--barely perceptible--change in color. As the exits the flame, there should be a light bluish color which develops at the shoulder or a little below it, while the shine remains on the case body. The loss of the shine is a clue that the case got a little too hot. On bottle-necked cases you will find that the neck turns to a noticeably deeper "gold" color.





If the cases have lost their shine, they were close to a red heat and may or may not be too soft. You can gauge the softness to some degree by using the Vise-Grip "test" described above. If the case mouth doesn't spring back after being slightly deformed, the case is trash. Don't waste your time with it.

When you get the faint blue color and the shine remains on the case, you have everything adjusted to perfection. Start stuffing those little brass cases in those little round holes until you're done. Make mental notes of your set-up, and you'll be able to repeat it in about three minutes the next time you anneal.

Ken Light BC 1000 Annealer BernzOmatic propane Torch

Selecting the Proper Torches

Some of the older type torches have large burner tips and very crude fuel control systems. Most of the newer torches have very efficient tips and fuel valves that are quite precise. The newer torch tips are small in diameter--about 1/2 inch--while most of the older models are in the 5/8ths inch range. There is nothing wrong with the older style torches, and you will find that they can perform quite well. However, if your torch's flame is hard to control, the tip "spits" or "flares", or the tip has become too deformed because of being dropped a few times too often and no longer delivers an even flame, some new torches may be in order. I happen to favor the BernzOmatic Model JTH-7 torch. The tip is efficient, and the valve is not too sensitive. Any equivalent torch will do nicely as long as the tip will fit through the torch holder. This torch will deliver about 4200 BTU.

When To Anneal
OK, now that you know how to anneal, you need to know when to anneal. If you shoot light loads, you can go a long time between annealing. Moderate loads will necessitate annealing a little more often. Normal loads will work harden the case after an amazingly short time. Hot or maximum loads will require annealing very often--something on the order of once after every two to four firings.

You must also consider that some work-hardening occurs when the brass is resized, so the number of firings do not tell the whole story. Another consideration is the chamber size of your gun. If you have a "loose" chamber, you will expand your brass more. It will need to be squeezed more when it is resized, thereby causing it to be worked a little more than "normal".

Another indicator is the opening up of your groups. When you start getting fliers and abnormally large groups, check your case necks along with all of the other variables; it may be time to anneal. If you're a chemist or metallurgist, you could acid-etch a case neck and microscopically inspect the grain size.

In the end, it will be your own experience that will determine the proper frequency of annealing--just like every other aspect of handloading, there are many variables which are peculiar to your particular problems, methods, techniques, loads, components and guns. You are the final judge.

The next question is, should cases be annealed before reforming? I will let Mr. Earl Naramore answer that Question ("Principles & Practices of Reloading", Small Arms Tech. Publ. Company, 1954):



If you are forming brass and have definite instructions as to when, where and how much to anneal, by all means, follow the instructions that you have been given. The "instructions" above are more in the form of "guidelines" rather than definite instructions.

The last question is, "Do I anneal before resizing, or after"? Theoretically annealing does not change the diameter of the case neck. In practice, it may or may not, depending on how much the metal is stressed. Therefore, you should always anneal before resizing.

About the Authors


Ken Light owns and operates Ken Light Manufacturing. A skilled designer and machinist, Ken has created a variety of unique products for shooters. His company specializes in products for Int'l Handgun Metallic Silhouette Association (IHMSA) and NRA Hunters Pistol Metallic Silhouette competitions. Ken started shooting silhouette in 1986 and has won seven (7) National Championships. Ken works with many of the top silhouette shooters to improvise and develop new products. In addition to the featured BC 1000 Automatic Case Annealer, Ken's company offers sight ribs, high rise mounts, extension mounts, triggers, metallic sights, blast shields, and accessories. Contact: Ken Light Mfg., Lake Havasu City, AZ, Phone: (800) 790-3184.

Editor's Tool Tips: Case Holders for Manual Annealing





Finally, some people to prefer to hold the case with their fingertips. In time you develop a "feel" for the proper temperature--or so the story goes. We don't recommend this method because you'll probably ruin quite a few cases, and potentially fry your fingertips, before you get it right. If you do use the fingertip method, use a temp marker on the necks of your cases. Available in solid or liquid form, in variety of temperature ranges (melting points), temp markers change neck appearance when you reach the set temperature (see sidebar).

DeSimone Explains Annealing with Powered Case-Holder

Successful long-range shooter Rich DeSimone, who holds the 5-shot IBS 1K world record, advocates frequent case-annealing: "On my 1,000-yard cases, I anneal every firing. Probably every other would suffice, but it takes so little time that I do it every time" He anneals one case at a time, but he uses a home-built powered case turner. He assembled a wood box, to which he fitted an $8.00, surplus electric gear reduction motor running at 60 RPM. The motor spins a case-holder he crafted. Prior to building this box, Rich simply chucked his case-holder in a portable electric drill clamped in a bench-vise. With either set-up, cases are secure, yet easily removed--even while spinning. The powered case-holder frees up one hand and speeds up the process considerably.

Rich tells us, "I use Charles Bailey's annealing method. Charles was the 2001 IBS 1,000-yard Benchrest Shooter of the Year. Charles and I shoot together at Hawk's Ridge in NC.

I've turned a small piece on the lathe to hold the cases, either for my powered wood annealing box, or my variable speed drill. (If you use your imagination, you can easily make something similar that will work.) The case sits freely in the case-holder, which is reemed slightly oversize, so it's easy to insert/remove the case. I also cut a step in the case-holder cup so I can use cases with both large and small rim diameters. The motor drive in the box runs at 60 RPM. When I used the drill, I set the speed to around 100 RPM, using a rheostat. RPM isn't critical--you just don't want the case flying out of the fixture, but it does need to turn so the heat is evenly distributed.


It works very well. I can do 50 cases in about ten minutes. I then let the cases sit in the CLR for an hour or two, then rinse several times and brush out the necks with a RCBS nylon case-neck brush. Make sure you have enough CLR in the bucket for the cases to be fully covered or you will get some marks. Remove spent primers before annealing so water will flow through the cases when you rinse and dry them. As far as drying--I just dump them on a big towel and roll them "to and fro". You can just let them air-dry or use a hair dryer to speed the drying process. Sometimes I'll hit them individually with compressed air, then use my heat gun to apply some heat. Overall the procedure may seem complicated, but once you get the hang of it, it's a piece of cake. — Rich DeSimone —




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