Re: New Brass, .243 Cracked neck
A couple of things:
First MPro 7 removes all the oil that protects the dies from rusting. It also is a water based solvent which if not fully removed from the dies may itself cause corrosion. Be sure to do something to protect the dies from corrosion after using MPro 7.
Annealing the brass incorrectly can be dangerous.
Under no circumstances can the area of the head of the case be heated at all. It has been heat treated to be able to withstand the pressures from the ignition of the powder that can be in the 60,000 psi range.
You must also use some indicator of the temperature of the case shoulder and neck that you are annealing. Get it wrong and the crystalline structure of the brass changes, making it significantly weaker than when annealed the correct way.
This annealing process is so critical that I will not do it. When the brass gets to the point where it absolutely needs annealing I replace it with new cases. I wish not to risk my guns or me to save a few bucks. Others here do it regularly and that is fine with me because they get to choose, as I do. I choose not to take the risk.