Regular vs. Magnum Primers

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Sep 15, 2023
Jamestown ND
one of the differences is that magnum primers have a harder cup than standard, so if you are loading for a firearm with a weak or short fire control parts you may encounter a higher misfire rate. other than this I would not hesitate to swap them without load adjustment unless you were at max pressure with standard primers.
Dec 22, 2017
I've done quite a few back to back tests with CCI regular and magnum primers with powders that I use just do answer the question to my satisfaction. As said about, usually a little higher FPS with the magnum... But otherwise, no change. None of my loads are on the bleeding edge either. The only exceptions I found was 2400 likes regular, 4227 likes Magnum. HS-6 likes Magnum. Never tested H-110/Win296, but I read a magnum primer should be used there.
Rclark did a pretty good job of explaining that some powders perform well with magnum primers while other powders perform well with standard primers.
Lots of members have posted that they have had success using either standard or magnum primers with many powders on target loads.
I know a number of people that use standard small rifle for hot pistol loads.
I also know some that have been forced to load standard pistol loads with small rifle primers because SR primers were available and no SPP were available.
So I believe all of those things can be done safely.
Now for why I felt I needed to post in this thread. When I was new to reloading away from home on my equipment rather than my Dad's equipment, I started with CCI Magnum LR primers to load .30-06 ammo. My groups were rather large and disappointing. I switched to another brand of Standard LR primers and my groups tightened up very nicely! Since then, I have always felt magnum primers caused poor groups unless the powder in use or the quantity of powder required a hotter burn to perform. I have no proof of this and I did not perform any reasonable level of experiments to prove it. Even if I had, it might have no relevance to pistol loads anyway.