When seating bullets into a bare clean brass neck, you can actually be compressing air within the case and sealing it within... Then, later, travelling to different locations/altitudes, can produce changes in temperature and or changes in density altitude... This will cause pressure changes within the case. (pushing or pulling on the base of the bullet)....
Seat bullets long, then, seat to desired OAL just before shooting, is a great idea...
Alternatively, with a sharp angled pic, scratch a lateral relief inside the neck to allow air pressure to equalize so bullets don't move outward over time/ travel /temp or altitude...
This does NOT address bullets seated months or years prior.. only recent reloads...
Caveat... Just a concept that came to me while in my armchair, with a fine Canadian 12 Year Whisky in hand... Not proven.. Only concept...
Seat bullets long, then, seat to desired OAL just before shooting, is a great idea...
Alternatively, with a sharp angled pic, scratch a lateral relief inside the neck to allow air pressure to equalize so bullets don't move outward over time/ travel /temp or altitude...
This does NOT address bullets seated months or years prior.. only recent reloads...
Caveat... Just a concept that came to me while in my armchair, with a fine Canadian 12 Year Whisky in hand... Not proven.. Only concept...
