Hello, I am having a XP-100 pistol chambered in a .300 short mag.. and have been asked by my gunsmith what bullet I will be using...and will the necks thicknesses be reduced? *Things I have not thought of before this project? As he will be chambering the barrel. and be cutting the throat for any dimension I require. 1. I was thinking of using a Berger bullet due to the fact their bullet jackets are thin...and would expand on game out to several hundred yards. 2. What are the real benefits of reducing neck thicknesses on brass...any help would be greatly appreciated? 3. The brand of brass will probably be Nosler...due to the fact that they are usually less damaged when first unpackaged. Any help or suggestions would be greatly appreciated! One thing I have learned in all my years of shooting and reloading...is that there is something to be gained by asking questions...and listening to others. Thanks!