If it's longitudinal, only the neck would have to be annealed. But annealing steel is going to be very, very tricky.
I would suspect that the heating around the neck area is most severe, and the barrel acts as a quick "quench" - meaning, each time it's fired, the neck exceeds 675F and then drops down very rapidly as the heat transfers. Then the casing flies through the air, which further cools it rapidly.
So each time the casing is fired, those necks are getting harder.. and harder.. and harder.
The problem with heat treating steel is it takes much longer to get the metal to reorganize itself, than it does brass. Normally to anneal steel you'd need to raise the temp to 700F for an hour, then cool slowly to ambient. That'll be difficult to do without messing with the rest of the case. Putting the cases in water is not going to work, the water will boil and evaporate WAY before the metal is annealed properly.
I don't think annealing is really an option, given the physical properties of the metal.
I would suspect that the heating around the neck area is most severe, and the barrel acts as a quick "quench" - meaning, each time it's fired, the neck exceeds 675F and then drops down very rapidly as the heat transfers. Then the casing flies through the air, which further cools it rapidly.
So each time the casing is fired, those necks are getting harder.. and harder.. and harder.
The problem with heat treating steel is it takes much longer to get the metal to reorganize itself, than it does brass. Normally to anneal steel you'd need to raise the temp to 700F for an hour, then cool slowly to ambient. That'll be difficult to do without messing with the rest of the case. Putting the cases in water is not going to work, the water will boil and evaporate WAY before the metal is annealed properly.
I don't think annealing is really an option, given the physical properties of the metal.
