How to Anneal Brass with the Annealing Made Perfect MKII (Photo by Yamil Sued)
October 14, 2022
By Jim Kauber
For most of us, reloading for long range has always been a game of “attention to detail,” whereas measuring to the thousandth and weighing to the kernel is the norm. One of the most important but time-consuming aspects of reloading is ensuring the consistency of our brass, including case life extension and rejuvenated malleability through annealing.
There are many well-written, in-depth explanations of the theory, metallurgic changes, measurement differences, and methods of annealing which I won’t delve into here. However, there was always a doubt about open flame temperature and exposure time in a one-size-fits-all method when it came to different manufacturer’s brass quality, calibers, and grain structure that I never felt confident the process was being done correctly. And then I saw the MKII induction annealer by Alex and Matt Findlay, founders of Annealing Made Perfect (AMP).
(Photo by Yamil Sued) With the AMP unit, you sacrifice one case to obtain a correct setting through unit analysis and then off you go. My intent was to discover velocity consistency differences between annealed and non-annealed cases when subjected to my normal reloading process and not to incorporate OCD reloading methodologies to see how long the cases will last or publish dissected case measurements to the half thousandth. After all, I reload to shoot, not shoot to reload.
The idea was to take 20 rounds of Alpha Munitions’ 6 Dasher brass loaded exactly the same: 10 rounds, no annealing, and then 10 rounds annealed after each firing. Data collected would be side-by-side velocity differences, extreme spreads, and standard deviations, giving an indication of consistency or variations of neck tension and bullet release. What I didn’t keep close tabs on were individual accuracy differences in group sizes between the annealed and non-annealed.
(Photo by Yamil Sued) Accuracy is a result of load development for a particular rifle after barrel break-in — so it would be of little value in this test. What I found with the 44 different five-shot groups was that all fell between .14 and .69 MOA. Perhaps this is a testament to the inherent accuracy of the BR-based case design, consistency of the Alpha brass, preciseness of the sizing die, and quality of the rifle.
Findings and Unplanned Observations In the test sequence, the annealed brass consistently produced on average lower velocities of 4 fps. It also produced lower extreme spreads, 21 vs. 25 fps, and lower standard deviations of 7.22 vs. 8.48 fps. Firing number two was an outlier with no explanation of why the non-annealed brass was 23 fps slower than the annealed when the rest of the test proved otherwise. It could’ve been something different I did in the loading process I wasn’t aware of. I asked Andrew Rixon, Alpha Munitions’ chief engineer, about why the velocities differed between the two. After drafting the graphs and compiling the data, he clearly articulated the related metallurgic principles of cause and effect.
(Photo by Yamil Sued) “It is observed that the non-annealed cases exhibit faster velocities than annealed cases,” said Rixon. “The increase in velocity is likely due to the increased neck tension from cold working brass without annealing. Cold working increases hardness and strength, constraining the bullet slightly tighter in the neck, resulting in a faster muzzle velocity.”
Not directly related to annealing but surprisingly evident was barrel/velocity speed up. When I began this project, a total of 95 rounds had been fired through the Dasher, and it kept increasing in velocity until firing #6, which coincided with 215 rounds total before plateauing off with an increase of 87 fps. What was interesting is the difference in the number of break-in rounds of this Benchmark cut rifled barrel and their button rifle barrels. This last year, I ran a similar test on a button rifled 6 GT. This barrel plateaued at 90 rounds with an increase of 85 fps — essentially the same increase in velocity but with less than half the rounds than through this Dasher. Speaking with Ron Sinnema, owner of Benchmark Barrels, we plan to do a comprehensive barrel speed-up test between cut and button rifled barrels to ascertain whether this is inherent or an anomaly between the two.
Generally, it can be surmised that the less you work the brass, the less of a difference you’ll see between annealing and not annealing. In retrospect, the firing of almost perfect brass then minimally working it in dies set-up specifically for this brass displayed little difference in velocity variation. To paraphrase Rixon, if you perform minimal cold work, the less change to the hardness of that brass you’ll see. This statement paralleled Alex Findlay’s who last year completed a comprehensive test at the Strategic Edge range in Tennessee.
“When we visited the Strategic Edge range in Tennessee last year for testing,” said Findlay, “we found that the smaller 6mm cartridge showed less difference between annealed and unannealed. David White was shooting a 6 BRA and got ridiculously good numbers. The larger cartridges tended to show a bigger difference between annealed and not annealed.”
In this game of attention to detail, annealing — regardless of how hard you work your brass — gives a quantifiable consistency advantage. You’ll for sure see this where it really counts — downrange.
