I need help with resizing

[IceAxe]

The annealing process if done correctly should/will not harm brass, the key is not to over temp the brass causing a chemical change. Multiple annealing's should have no ill effects... if not over temping. I only use automated equipment to maintain consistency and temperature. I have some 6mm x 45 cases with well over 40 reloadings/annealing. One reason people do this is to have a uniform neck tension. You can often feel the variations in neck "stiffness" in the form of resistance when seating bullets on cases with necks of varying degrees of hardness.. I would never anneal by hand as a single over temp would vaporize the zinc leaving only copper and ruin the case (by denaturing the brass).

http://www.6mmbr.com/annealing.html