O.K. I am having trouble finding small and large pistol primers. However I can get plenty of magnum ones. Can they be used in the 9mm and .45acp if I reduce the powder charge and work up?

doesn't sound like a good idea to me; magnum and non-magnum primers are made for different purposes and to be used for different applications under different circumstances. ALL of the loading books i see say never to use mqagnum primers unless called for, and vice versa.

using a magnum primer when not specifically called for would produce, at best, unpredictable results. at worst, you could have yourself a major problem.

I use magnum primers in my 38spl rds that I fire in my 357 as well as light loads in my 44mag.

I would not take a high pressure load worked up with a non mag and simply stick in a mag primer. I would have no issue with simply using a magnum primer and working up a new load.

magnum primers work fine, but be positive to start low and work up the load as the primer does flash hotter.

Reduce your powder charge 5% gives about the same vel. Since vel.=pressure, all things being the same, you'll be fine.

Yes, just reduce the load some and work up. I use mag primers in my 10mm, and have used mag primers in my 40 ammo.

I had that very same question last year and called CCI about it. They said it would be alright as long as you dropped your charge down a couple of grains of powder. I've got a couple of cases of small magnum primers and I hated to see them go to waste.

Thanks for the input. I got a package of both large and small magnum primers to try.
I also lucked into 2000 regular small pistol primers and 600 large.