Whats the difference between a “standard” primer and a “magnum” primer?
A magnum primer provides a longer flame duration, a higher flame temperature, or both. In some primers (the CCI small pistol primers, for example) the magnum primer may have a thicker cup to better handle higher pressures. Use magnum primers only where recommended in published load data. Substituting a magnum primer for a standard one without a charge adjustment will nearly always increase pressures. We use Magnum primers in data development with many ball propellants, and with very large-capacity cases. They are also a plus when you are shooting in temperatures below 20 degrees F.
