I have been reloading for 50 years, and my unscientific research as shown me that neck splitting on pistol brass, either brass or nickle plate is caused by work hardening the brass. Crimping in and folding out on firing plus belling the mouth, causes the brass to harden, and finially split. On rifle brass while you don't crimp, you are still work hardning the mouth of the case. Firing the shell causes the case to stretch forward, and also to expand and contract. A simple annealing of the cases after say 5 or 6 reloads will stop a lot of the necks splitting. It softens the case neck. All case necks are anneled at the factory before it is loaded for that reason, to make the case mouth softer. brass properly taken care of and not loaded to max loads all the time will last for years. Day before yesterday I loaded a box of Peters 270 cases I bought sometime in the 50's. I have no idea how many times this brass has been loaded, but say a lot. It still is in good condition.
