Only FMJ bullets allowed through the post expanding bullets are face to face with registered dealer brass OK powder OK but costly carriage .
With regards to the spare 4mm you have in your magazine you might be able to use some of this to have a longer COL they do say 15 to 20 thou jump from ogive to rifling but this is not always the case only by trial and error will you find the best combination for your rifle (SAFETY SHOULD BE FIRST IN YOUR MIND) As others have allready said a good reloading manual will do most of the work for you giving a multitude of safe bullet and powder combinations.