From the AMP Annealing website:
When to anneal?
What is the correct sequence - anneal/resize or resize/anneal?
If annealing brass that has had multiple reloads or is unknown history, we would strongly recommend annealing first followed by resizing. This is because the harder the brass, the more likely it is to resist conforming the resizing die and "springing back".
Our settings target an annealed neck hardness consistent with virgin brass, (some cartridges are a little higher or lower). Because the process anneals both the neck and shoulder, die conformity will be correct when resizing. Note: we have found that the target annealed hardness is reached reliably regardless of the starting hardness i.e. it doesn't matter if it starts at 20% harder or even 70% harder, it will still come back to the same hardness.
If, as we recommend, annealing is done every reload, the brass is always soft enough in the neck and shoulder to resize accurately either before or after annealing. We have, however recorded consistently more uniform hardness test results by annealing beforeresizing, and we therefore recommend that sequence.
We find that the best results are obtained with this sequence:
- De-prime - optional depending on your cleaning sequence)
- Clean - tumble or ultrasonic etc. – again optional. Cleaning won’t affect annealing
- Anneal
- Lube - this is vital even with nitrided dies. (Imperial wax or spray such as Hornady One Shot) – note: Dry media graphite tends not to adhere well to annealed cases. We do not recommend its use.
- Resize - after annealing, THE SIZING DIE MAY NEED TO BE ADJUSTED for both shoulder bump and neck OD to account for zero spring back. See FAQ 3, 5 and 6. De-priming can be done as part of the resizing process.
