Case head seperation is usually a result of improper head space or miss adjusted sizing dies. Most problems with case length growing to excess is caused from draging the expander button thru the case neck during the resizing operation! The other leading cause is loading to excessively high pressure. The best cure I've found is to use the Lee collet die. This eliminates the problems of lubing the cases and also doesn't stretch the brass. Another benifit seems to be smaller groups. A win-win situation! If you are having case head seperation within 3-4 loadings you have a very real problem, and shouldn't shoot that rifle until you have it checked by a compitent gunsmith.