I read a technical article published in American Rifleman or Shooting Times (or... one of those) where rifle-primers were tested for pressure -- standard vs. magnum primers in pressure barrels and using chronographs, etc. (sounded fairly scientific, and I'm easily impressed anyway...)
The surprise was that for many / most loads and powders, the pressure DROPPED (was lower) with the Magnum primers.
This does NOT automatically apply to all loads in all firearms -- but it sure did run opposite of logical linear thinking.
Some brands of Mag. primers burn longer, not just 'hotter' or 'bigger' so combustion improves, and pressure-over-time curves are altered, etc.
One of the guys in Hodgdon's testing lab published a comment recently (on another shooting / reloading board) about mag-primers mechanically breaking down powder kernels, which in turn, changed the powder 'burn-rate' which in turn, increased pressures substantially.
Ya get 10-engineers in a room, and ask a question -- Ya get 12 or 13 different opinions every time. Ya get 10-engineers and ONE accountant in the room, ya get NO OPINIONS at ALL !!! --CC
