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Proper Case Neck Annealing Extends Case Life and Increases Accuracy

The proper annealing of cartridge case necks — never the body or head — extends case life and increases accuracy. Here are some good ways to do it.

Proper Case Neck Annealing Extends Case Life and Increases Accuracy

Annealing cartridge cases extends case life and, done correctly, can benefit accuracy. (This is not a recommended method, by the way—just a photo illustration.) 

Most handloaders have heard of annealing, but few actually do it. And candidly, in normal times, few really need to. However, today there’s a new need, as shooters who are reloading more than usual due to the dearth of ammunition want to conserve their brass.

In the past, annealing was mostly the province of competition shooters who fire thousands of reloads per year—and sometimes per month—and the occasional vintage cartridge shooter with a few really old cartridge cases he or she wants to keep in good condition for continued use.

So just what is annealing? It’s the process of softening the granular structure of the brass in your cartridge case necks after it’s become work-hardened by several firings. This is accomplished by heating the necks to between 700 and 800 degrees.

Critically, though, while cartridge case necks benefit from annealing, case bodies and case heads must never be annealed. They are intentionally work-hardened during creation in order to withstand extreme pressure and resist deforming. If accidentally annealed, they absolutely must be discarded, because if loaded and fired they can rupture and jet superheated gasses rearward through the bolt.


If that’s a risk, why is annealing beneficial? Properly done, there are two reasons: much-extended case life, and increased accuracy because the malleable brass of properly annealed case necks applies consistent, ideal neck tension. Improperly done, case life is still extended, but accuracy actually decreases because case necks of varying softness grip bullets inconsistently.


Brass is an excellent heat conductor. As a result, it’s necessary to heat necks fast, with an aggressive flame, and to employ some sort of heat sink around the base. Otherwise, the risk of annealing the base via migrating heat is too great.

Plated cases can be annealed like any other, but temperature is harder to gauge because they don’t show color with varying degrees of heat.

To gauge case neck temperature, there’s a product called Tempilaq. It’s available in several forms, including crayon-like and lacquer-like stuff reminiscent of fingernail polish. The latter is most useful. It can be obtained online, and sometimes from your local hardware store. Purchase the 750-degree indicator, and paint it inside the necks of your cartridge cases. Why inside? If applied to the outside of the case neck, it indicates the temperature of the flame bearing onto it instead of the actual temperature of the brass.

There are a number of methods to maintain the consistency you want to achieve in the annealing process. I’ll start with basic, simple techniques using equipment that costs little and work up to state-of-the-art annealing machines




Benchrest shooters pioneered home-built, metal, rotating pedestals for a case to sit in while being heated with a propane torch. The rotating pedestal made for even heat application around the neck, and the metal pedestal—countersunk to hold the case—served as a heat sink to keep the case head cool and protect its hardness. Often simply chucked into a drill, these devices led to rather more sophisticated machines offered on the retail market.

Savvy DIYers can create their own with a simple slow-RPM motor and a lathe to turn custom case pedestals. (As an aside, Hornady made a simple annealing tool made specifically for use in a power drill, but it’s been discontinued. You may find one used online or in a dusty corner of your local reloading shop.)

Moving up a step, a company called Anneal-Rite offers a setup with a double-ended cartridge pedestal plied by two propane torches. Retailing at about $115, it’s rated to anneal around 500 to 600 cases per hour. Tempilaq is used to read temperature and achieve consistent annealing. Check it out online at CartridgeAnneal.com. It’s a simple, sensible method.

Recommended


Taking a significant step up in sophistication and cost, Brownells (brownells.com) and its sister company Sinclair International sell an annealing machine by Bench-Source. Retailing at a cool $580, it features a wheel-type rotating index plate with 10 case positions. When each case moves onto the heating position, it’s rotated on a metal spindle while two propane nozzles apply heat.

Heat time is adjustable, enabling the user to calibrate the machine using Tempilaq until it applies the desired anneal. The machine’s table top and index plate are made of metal to serve as heat sinks, and are fan-cooled to prevent heat buildup. Like the Anneal-Rite, it will anneal between 500 and 600 cases per hour. However, aside from setup the system eliminates human error, so your cases will be absolutely consistent.

Finally, at the top, both price-wise and in capability, is the AMP (Annealing Made Perfect) Mark II Annealer. Price is an eyebrow-raising $1,395, but at least it includes shipping. It comes with three cartridge-specific pilots of your choice, and additional pilots are available for $20 each.

Why does it cost so much? It uses induction heating rather than direct heat, just like those newfangled kitchen stoves that feel cool to the touch but heat induction-compatible pots right up.

Even better, the AMP Mark II (AMPannealing.com) is infinitely adjustable in small degrees, so achieving a perfect, and perfectly consistent, anneal is easy.

AMP publishes settings for myriad cartridge cases—right down to include case manufacture—on its website. Handloaders can simply plug in the published settings for their cartridge case type and manufacture and go to work.

Prefer to analyze your own personal cases and calibrate accordingly? The Mark II comes with an Aztec mode designed specifically for that process.

Clearly, because of cost, this is a machine for professional-level competitive shooters and passionate recreational shooters. Impressively, an accessory kit called the AMP Mate is available to pair the AMP annealer with a Hornady or Dillon case feeder to fully automate the annealing process. A lot of money is at play, but when a shooter’s quest for perfection trumps the padding in their wallet, it’s absolutely the way to go.

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