Thread: So how much difference does the primer make?

Originally Posted by Cigar

So I stuffed up and primed some cases with Federal 210s instead of the CCI 200s I use in that calibre and have just finished load development with. I realised my mistake straight away, so started again from scratch for my developed load.
Being a Kiwi of Scottish descent I didn't want to waste 14 primers so loaded those cases up with a starting load to use as plinkers, barrel foulers etc.
Does anyone have any info on how much effect make of primer has on pressure or velocity?
I realise Federal primers are considered softer than most, so i wanted to play it safe. The load used is 2 grains lower than my developed load and 3 grains lower than I have tested with no pressure signs.

Short answer it wont make any difference a long as they are std or match primers.
Magnum primers are actually less brisant ( the technical term for the detonation characteristics of an explosive) they produce the same amount of energy but over a longer period ie a longer burn time. The reasoning being ball and heavily retardent coated extruded powders used in high capacity magnum cases dont always ignite in a repeatable fashion with a short sharp thump and need a bit more encouragement.
With faster powders you reportedly do get more velocity and pressure spikes as the initial ignition phase starts with more powder burning.
I understand that in sub zero temperatures magnum primers give more consistent ignition and velocity than std ones which kind of makes sense,
As someone who isn't primarily long range target shooter and is a bit of a scrounger I have never noticed any difference between standard primer brands including match primers that couldn't be accounted for by operator error when shooting out to 500 meters which is the "limit of my competence" so to speak especially on game.