I usually make the front sight much too high, so the gun shoots low. While at the range, I file the front sight down until the bullet hits about 2 inches high at 25 yards. Then later, back at the shop, I dress the front sight to give the proper shape. I do not worry about the shape of the sight while at the shooting range, only the height. Back at the shop, with a good vise and a variety of files, I do the final shaping. I do not use any protective covering on the barrel, just be careful.
Jim