By Tom Wilson
So, you have been reloading for a while. You accumulated a supply of brass for your favorite firearms. Now you find you are losing brass with necks cracking after 5 to 7 shots. Premium quality rifle brass is rather expensive; .338 Lapua will dig into your wallet at the rate of $2.80 each; less exotic hulls like .308 Win. .75 cent each for the high quality stuff.
Now you are contemplating prolonging the life of your coveted brass as you have heard of cartridge case neck annealing. Some knowledgeable shooter at the range advised he does this and stated that accuracy increased and case life was greatly extended. This experienced gentleman may have also advised if you accidentally anneal the case head you have created a very dangerous situation. If the case head is annealed it can blow out when fired, wreck the firearm and possibly injure the shooter. After hearing this you may have put the idea of annealing case necks out of your mind for a while.
As time has progressed you may have scrapped your original supply of cartridge cases and are now experiencing loss on your subsequent stock. A bench rest shooter who anneals his brass after every firing reported reloading one batch of brass for the 58th time. This represents a dramatic extension of brass life. By now you may have decided it would be prudent to at least investigate case neck annealing.
Many years ago an attempt at annealing was tried, with unacceptable results. At that time cartridge case neck annealing information was very limited. The instructions were to stand the cases up in a pan, add water to a depth 1/3 up the side of the cases. With the cases setting in the water bath the case heads could not be heated above 212 degrees F. the boiling point of water. The instructions said to heat each case neck with a torch to a low red glow evenly all of the way around and then tip it over into the water. No mention was made as to the proper temperature the case neck needed or what might happen if over heated. Thus with the information available annealing was begun with the cases standing in water. A small propane torch flame was applied to the case necks. There was no way to measure neck temperature and a number of the .30-06 cases were over heated. After all, if a low red glow is good then a bright red color had to be better. Seemed like just pure and simple good logic, right? And by the way what temperature is brass at a low red glow anyway? Years later it was determined a low red glow, even in dim lighting, is too hot. All of the cases on hand were annealed in this manner. At the next reloading quite a few cases were lost due to the shoulders collapsing even though they were just neck sized. The necks and the top of the shoulders were too soft. Nothing was gained in conservation, just more scrapped brass. At this time cartridge case neck annealing was relegated to the shelf.
Years later the sport of high-powered rifle silhouette shooting became of interest. This presented a need for a good quantity of 7.62x51 brass. A large supply of once fired military brass was obtained. A good portion was match brass fired in match rifles. Mixed in was a larger quantity of brass fired in machine guns, which have generous chambers. For this reason it was determined the entire lot, around 1,000 pieces of brass should have the necks annealed prior to being put into service.
It was now time for research, to obtain accurate information. It was soon found that cartridge case necks do not have to be quenched in water after they are heated for proper annealing. The old method of standing cases up in a pan of water only assured the case heads would not be annealed. Cartridge brass is 70 percent copper and 30 percent zinc. It begins to anneal at precisely 482 degrees F. Research revealed 700 was the low and 800 degrees F. the high to successfully anneal cartridge case necks. Once quickly brought to that temperature then air-cooled proper case neck annealing is achieved. The goal was to devise a method to bring the case necks to the center of the proper temperature range, 750 degrees became the target temperature. At the same time heating the case head to less than 450 degrees would retain the brass temper in this area. This became the parameters to successfully anneal the case necks.
An infra red heat measuring gun to get accurate readings was researched. The manufactures advised to obtain accurate readings all brass had to have the same reflective finish. Next the infra red gun would have to be calibrated to that finish. This would be doable as most serious reloaders clean their brass anyway, this would require inspecting all brass in the batch being worked for a uniform finish. The manufacturer of the infra red heat gun then stated it would not read the brass temperature correctly if the beam was directed through a flame. For this reason the heat gun was ruled out. It was determined neck annealing occurs rapidly, the case necks would be in the annealing flames for only a couple of seconds,
Next to be tried for accurate temperature detection was a crayon-marking device called a Tempilstick. These are used in industry and are available in a wide range from 125 to 1,800 degrees F. One was purchased rated at 750 degrees F. It was tried on the outside of the case neck and did not work. A call to the manufacture revealed when flame directly contacted their product it would not give an accurate reading. The next product was 750 degree F. Tempilaq heat indicating liquid made by the same firm. This product comes in a 2-oz. bottle with a small brush attached to the inside bottom of the cap allowing easy application of a small dab inside the case neck. Once applied the Tempilaq dries quickly. The dab is easily visible and the flame impinging on the outside of the case neck would not be in contact with the Tempilaq. This worked superbly. The Tempilaq heat indicating liquid is guaranteed to +- 1% for a total tolerance of just 15 degrees. Bingo, problem solved in instant and precise temperature control. For safety a bottle of 450 deg. F. Tempilaq heat indicating liquid was also purchased and applied on the outside of the case from the case head upward about 1/3 the length of the 7.62x51 cases. The 450-heat mark would not be in the flame and if it did not change color it would indicate the case head had not been annealed, this is critical information for safety. Later on when annealing was set up for the 1,000 - 7.62x51 rifle cases no annealing occurred on the case heads which was a terrific result. From this it was determined any rifle case longer than 1.75 inches did not need the 450 deg. F. Tempilaq on the case head. The 450 deg. F. Tempilaq is used on cases from .800 to 1.75 inches long to assure case head annealing does not occur.
There are a few carousel style cartridge brass annealing machines as well as other designs on the market. The prices for these machines run from about $400 to $500. As this type of device performs only one step in preparing brass for reloading, it did not seem cost effective to invest that much for a machine accomplishing just one operation.
A new design was sought; it would have to be efficient, practical and affordable. A design that would get the case neck into the flame and out quickly as soon as annealing occurred. The design that evolved utilizes a rotation like a Ferris wheel. A prototype was built using a 1” square aluminum block 4” long with a hole about an inch deep and larger than the outside diameter of the cartridge case drilled in either end. This design allows the base of a cartridge case to easily slide in and fall out. A hole was cross-drilled in the center of the 4” aluminum bar to accept an axle. This aluminum bar is now referred to as the Cartridge Case Holder. A wooden knob was installed to turn the Cartridge Case Holder by hand since the aluminum bar gets hot in use. The case is inserted with it out of the flame and then rotated up vertically into and between two opposed propane torch flames impinging on the case neck. This prototype worked perfectly. Production models were produced with propane cylinder holders. This unit is now being marketed as the Anneal-Rite Machine. Ten standard Cartridge Case Holders are available which accommodate many hundreds of different cases from .40 S&W pistol with the largest one taking .50BMG and even .600 NE cases. Special size Cartridge Case Holders can be ordered at reasonable prices. The entire unit with one common size cartridge case holder sells for less than a hundred dollars including one bottle of 750 Tempilaq. In time studies 500 to 600 cases per hour can be annealed. The Anneal-Rite comes with a money back guarantee assuring perfectly annealed cartridge cases. An eight minute video can be viewed and the Anneal-Rite purchased from Enterprise Services, LLC their Website is www.cartridgeanneal.com or by calling (479) 629-5566. You do not have to suffer with premature case failure, or spend $400 or more. Increased case life and accuracy will be the benefits. A 5 shot 5/8” group was recently achieved at 300 yards using the neck annealed 7.62x51 cases.
This article first appeared in Small Arms Review V16N3 (September 2012) |
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