I have a couple of thousand of CCI250 (Magnum) primers. I don't have a need for this many but I don't know what to do with them. Do any of you substitute the magnum primers for standard primers? Can anyone give me some guidance on using mag in standard reloading applications?

Given the current primer shortage, I would keep them. Unless you give them a bath, they shouldn't go bad. Or you could find someone locally who needs them. They are a hazardous material, so the shipping cost to send them to someone probably isn't worth the hassle.

As far as using them in lieu of a standard primer, guys will sometimes do that in cold weather or with ball powder, but without backing off a bit and working up, they are NOT interchangeable. And they may or may not give the same accuracy.

LWD

Trying both magnum and standard primers in a cartridge is something I frequently do. In cartridges of 308 Win. size and larger, I've found they're interchangeable. Usually accuracy is the same but some of the time I get better accuracy with standard primers. Occasionally I get better accuracy with the magnum primers.

If I were running my loads at the ragged edge of maximum, I would probably back the powder charge off a couple of grains and work back up.

I wouldn't worry too much about using magnum primers in lieu of standard primers. Like Grumulkin I would back off the powder a grain or so if my load with a standard primer was hot.

I’ve work with magnum primers in rounds like the 220 Swift, 243, and 25-06 and for the most part I’ve never noticed a difference other than a change in grouping or group size. I’ve never had a magnum primer help a load that I’ve already developed with standard primers though.

I would use them and work up a new load.

Thanks for the info. You are right about the shipping cost for hazardous material; that is why I am interested in using the. I don't normally run the "ragged edge" of velocity and pressure but I will observe your caution to back off and approach my load work up with a bit of caution. Thanks again.