Factory loads are what I would try next. If the same problem persists, then I would send it back to the factory.
Everything 123...said in his first post is spot on.
I also might add, grab your micrometer, and a headspace gauge, and take ALL your case dimensions (neck, shoulder, "L", headspace) on your reloaded rounds. Then check all the same dimensions of the fired cases. That usually tells the story.
One other possibility is the relation of the bullet's ogive to the lands in your rifle. I wouldn't assume just because you loaded according to the book, you weren't jamming the lands. That alone could lead to excessive pressure. I just had that happen to me with minimum charged loads.
Take all the measurements on your unfired, and then fired rounds, and you'll find out what is going on.
