I got a 1000 cci250 mag. rifle primers free. Is it ok to use them in 25-06 and 300win mag or should I use the standard ones? Why spend the money if I don't have to!

You can use 250s in those rounds with no problem. The 25-06 generally calls for a standard large rifle primer so IMO I would start my load development with 1 grain less powder than normal.

Working up your own loads with those will be fine. Many loads with ball powders will recommend them anyway. If you are going to switch primers, even back to standard, back off a bit just to be safe, then work back up.

Free is free!

Cheers,

Dan