I've been loading 4.0 grains of Bullseye and a 150 grain cast bullet with a CCI 500 primer for practice loads in a .357 mag. Like most of us I can't find any 500 primers but did locate some Winchester magnum primers. Are these primers ok with that load or do I need to make an adjustment to the powder charge?

Load and shoot. You won't be able to tell the difference.

it'll work fine ,,, pretty light load, yeah?

Thanks, guys, I thought it would be ok because it's a pretty light load but it's better to make sure than to take a chance. These are strictly practice loads and they shoot more accurately than higher power loads so I benefit by using less powder thus more rounds per pound, and get good accuracy.

I know the answer because I have done experiments.

If the load book literature were aimed a little higher level than dumb consumers, one could look these things up.