Have you ever wondered what is different about a "match" primer? Primers work by igniting the powder within the cartridge case. There are many variations of primers and how they ignite. This depends mostly on the temperature and/or rate at which the primer will ignite the powder. Match primers are designed to ignite more consistently and more uniform than standard primers.

Why would you need this? More consistent reactions are going to produce more consistent results. A primer that ignites and burns powder more consistently will produce a much smaller variation of muzzle velocity. In turn, this leads to greater accuracy and consistent groups on target.