Congratulations Woldan on making a fine rifle from a kit. I have never seen a kit for a centerfire rifle before but, I would have grabbed it just as you did. 7x57 is my favorite chambering and until you have that sharp corner of the chamber corrected, my recommendation is to just load 4 rounds and be happy. After all, if you haven't finished the job in 4 rounds, the 5th probably won't help. ;-)