A couple of weeks ago, while talking about annealing,
@918v mentioned that he saw velocity drop load to load when he annealed every shot. He mentioned that he has shifted to annealing less than every shot (I think he mentioned 1/4, but I can't find it - perhaps he will post here). He called it "over-annealing", but that technically means you've cooked a case by getting it too hot - we need to come up with another label here...
Per AMP, annealing every time - or even annealing multiple times in a row - does not offer different results.
So, which is it?
I tend to agree with much of what
@918v posts, so I don't discount what he's saying. At the same time, AMP is certainly in the know here too.
I decided to run what will likely be the first of many tests in this regard.
What I did:
- I took new Lapua brass and prepped as follows: uniformed flash holes and primer pockets, trimmed/chamferred/deburred, mandrel, neck lube
- After the trim step, I annealed every piece of this new brass. With five pieces, I annealed them four times, letting them cool completely between annealing
- I then primed, charged and seated (using an AMP Press)
Here are the plots (annealed 4x in blue):
Notes:
- As you can see, the 4x annealed cases show markedly lower seating forces.
- This is likely to have been caused by the brass being slightly softer.
- If these two sets of cases were shot next to each other (and I will do so hopefully tomorrow, but I might have Covid...), you would expect to see slightly lower velocity from those with lower seating forces.
- This is not 100% analogous to annealing four times over four shots because in that case, the brass would be getting worked during each shot, so I wouldn't expect this much of a drop
What's next? I don't know. I have to noodle on what would be a good test here to see how much this impacts things - I also hope I don't have Covid so I can test these tomorrow.
