Case Annealing

Many years ago, when I competed in High Power rifle matches with an AR- 15, 5.56 ammo was cheap and plentiful. Even though I was not reloading, I picked up my brass after each string of fire and saved it. Over time, I had accumulated several thousand cases. I ended up selling most of it to a local gun store for a few pennies per case. Fast forward several years. I switched from High Power to long range Benchrest with the AR and a few bolt guns.

I replaced the barrel on my AR-15 with one chambered in 223 Wylde to improve its accuracy. I started reloading to save money and try different powder and bullet combinations. When I started reloading for these rifles, I found that there were quite a few with cracked necks. Realizing that it was time to start annealing the brass, I looked to the Internet for help. The case neck and shoulder are work hardened with repeated firing and reloading and become brittle.

They need to be annealed to make the brass more ductile. This is a 308 Winchester case; I don’t recommend doing this with 223 Remington brass. Far The cases should not be annealed any further along the length than roughly 0.3" down from the shoulder. Annealing the full length of the case significantly weakens the case head and primer pocket which can result in catastrophic failure. You Tube has many videos on how to anneal cases and there are several commercial and homebuilt devices to do it.

There are two means of heating the brass: propane torches and induction heating. Propane torches are inexpensive and are more commonly used. There are two basic categories of devices, I’ll call them vertical spinners and horizontal spinners. The commercial versions are typically horizontal spinners that index the cases automatically while the home-built ones are vertical spinners where the cases are gravity fed into a rotating drum.

Some of the home-built spinners are quite ingenious and allow high volume annealing. I wasn’t interested in high volume use and decided to build my own, simplified horizontal-type design. In my design, the case is placed in an arm that is manually rotated about 60 degrees to put the case into the flame, where it spins on a small turntable. The arm is then rotated another 20 degrees where the annealed case drops off the rear edge into a collection pan.

The major items I had to purchase were a low cost 12 VDC (Direct Current Voltage) motor ($13), a mounting bracket with hardware ($9), and a power supply ($10), all from Amazon. Amazon makes things easier sometimes by showing additional parts that can be used with the primary purchase, such as the mounting bracket designed for the motor. I had most of the remaining material in my shop, including apiece of 3/4" square aluminum tubing to make the arm. I had some plywood

Brass nut has a 6 mm inside diameter. leftover from a previous project plus some other various bits and pieces needed. I purchased a few "nuts and bolts" type items as well. This article is not intended to give a detailed plan for the project as the concept is simple and can be adapted as needed. Assembly Details The motor brand I used is Greartisan and it has a small gearbox on the end of the motor with an output speed of 50 revolutions per minute.

There are several versions available with output speeds ranging from 5 rpm to 300 rpm. I figured that 50 rpm would be okay but don’t think the rotation speed is critical. The mounting bracket comes with the screws to attach the bracket to the motor and a small brass nut that is 0.45" in diameter (across the flats) which is large enough to for the case heads.

The nut has a 6 mm bore diameter that matches the mo- The white connector came with the adapter, I purchased the bulkhead style connector separately. tor shaft diameter. The set screws to secure the nut to the motor shaft are included as well. The 110 VAC (Alternating Current Voltage) to 12 VDC power adapter is rated at 2 amps and should be more than adequate for such a low torque application. The power adapter came with a female socket but it wasn’t a bulkhead type so I purchased one of those.

I built the frame from 3/8" and 1/2" plywood. It is 10" wide, 9" high,

and 6" deep. Again, these are rather arbitrary dimensions, they can be whatever works best for the user. Some may question the use of wood but since the flame is well above the top surface, I wasn’t concerned. This was a proof-of-concept design; it would likely need changes and wood is easier to work with than metal. The only critical dimensions are making sure the hole in the top of the frame is aligned with the motor shaft.

With the motor on the mounting bracket, I determined where I wanted it relative to the top of the frame. I installed the motor on the rear panel and measured where the corresponding hole in the top of the frame needed to be. I made that hole slightly larger than the nut diameter. I mounted the motor to the frame with the brass nut bottomed out on the motor shaft and the top of the nut slightly below the top of the frame.

I glued apiece of 400 grit sandpaper to the top of the nut to give the case head a little more traction. I then raised the nut so it was flush with the top and tightened the set screws. I added a front mounted switch to control the motor. I drilled 0.40" diameter holes through one end of the arm for .223 cases and 0.49" holes in the other end for 308 Winchester or 6.5mm Creedmoor cases. These hole sizes are not critical, they just provide a pilot for the cases to rotate within.

I added a hole for a pivot pin half-way between the other two holes. This allows me to anneal either size case simply by swinging the arm 1800. The pivot pin is a 0.25" outside diameter x 1.0" long screw post with internal threads on one end. It was too long so I added a spacer on top of the arm to take up the excess clearance. There wasn’t enough thread depth to allow shortening the post and the arm is a nominal 0.75" but measures 0.77" which is just a bit too large for a 0.75" long post.

The threaded end sets on a fender washer on top of the frame and is retained by a bolt installed from underneath. Out of curiosity, I put a 223 Remington case in the .308 hole. It rotated fine, just had a slight orbit, which shouldn’t be a problem.

I installed a 3" U-bolt (3/8" thread) on the propane cylinder and added thread connectors and 3" long bolts to level the torch nozzle horizontally at the shoulder of a .223 case. This determined the height of the frame at 9". Backing out the bolts raises the nozzle to accommodate the taller .308/6.5 cases. The type of nozzle used will affect the height required.

I made a spacer that butts up to the side of the frame and I push the legs of the torch against the spacer to set a constant distance to the cases being annealed. When the frame was completed, I stained and sealed the surfaces. Color change is the most obvious means of telling when the brass has been annealed. Temperature indicating paint such as Tempilaq can be used but should be applied to the inside of the neck where it won’t be burnt away by the flame. This typically requires paint rated for 600 or 650 degrees.

Similarly, 400 degree paint can be applied on the outside of the case about halfway between the shoulder and case head to prevent over-annealing. When the paint melts, you know you have reached the indicated temperature. I found that the color change is obvious and is a suitable means of determining when the correct temp has been reached. In the photos of the .223 and 6.5 cases, I marked the end of the heat affected zones with a felt tip to make it easier to see the differences.

If the brass starts to glow, it’s been overheated and should not be used. After I determined the amount of time needed for the color change (typically five or six seconds) with a few sample pieces, I used a simple timer to tell me when to index the cases through the flame. I found that it is easier to see the color change if I tumble the brass beforehand to give a uniform surface finish. Turning off the light directly over my bench also helps.

The amount of time required to get the correct annealing depends on the torch nozzle, shape of the flame, distance to the case, etc. I can cycle a case through the process about every 8 or 9 seconds. I annealed 100 cases in 15 minutes, then full-length sized them. None were cracked. This turned out to be a fun and interesting project. It didn’t cost much and it provided a consistent method of annealing cases which

Annealing for five seconds appears to be the correct amount of time for this method. 5mm Creedmoor cases, left to right, cases annealed for six seconds, eight seconds, and ten seconds. Annealing for eight and ten seconds is too long. should increase the number of times they could be reloaded. Unfortunately, the shortage of reloading components, especially primers, has prevented me from doing any loading lately. AG American Gunsmith Reader Services 1.