I am new to reloading. I was given around 1500 CCI 250 large rifle magnum primers. These primers were from a friend that died several years ago. They have been stored in his garage for about 6 years, the humidity is pretty high in these parts, would they still be good? Also they are magnum primers, would they be ok to use with regular load data .I do not max load anything,for example in my 270 win I load 59.3 gr H4831sc ( max is 60) . Would these primers create too much preasure or would I have to back the powder charge down more to compansate for the mag primer? Also would it be ok to use these in my 243 and 22-250 rifles?

Well as for the humidity I can't say, but you could prime a few cases with them and try to fire them in your rifle (no powder/bullet, just a case with the primer). If you use them in place of regular primers start back at the recommended start load and work back up, they may or may not cause pressure problems. As for use in other calibers, they will fit in any case that takes a large rifle primer. I don't know off hand if the .22-250 or .243 do, any good loading book could tell you.

Good luck.

For the price,I would get new ones...

Do what icthruu said. I'll bet they're OK!