[Brian Pfleuger]

Yes, it's a hardness issue.

Annealing would help but can be dangerous if over done.

You must anneal the neck, shoulder and perhaps 1/4" down the body but no further.

Even without annealing, most rifle cases that have been properly resized should last a dozen or more reloads.

My opinion of annealing has changed a bit over time. I first concluded that a novice could not safely do it without fairly extensive equipment or trouble. I have since concluded that it's not as complicated as I tried to make it.

Heat doesn't do anything at all to brass until it gets to (IIRC) 495F. At 495, it takes quite a while to anneal. The rate of annealing is somewhat exponential though, small increase in temperature decrease the annealing time dramatically.

I've settled on a "time honored" method. Well, it might not be honored but it's been done for years.

I hold the case about 1/2" below the shoulder and hold the shoulder in the "inner" flame of a propane torch. I rotate the case in the flame until it's too hot to hold and then drop it into a bowl of water.

Imprecise but effective, for me.

I can feel the difference when I size the necks.