Not an expert! I quoted T/C on another thread about bore size in .54. The top band is larger than the bottom and middle bands. I do no size them, but run them through the lube "tool" they use to sell. I do not believe this sized the bullet at all. When the bullet is in the right position ( a bit tricky!) a squeeze of the tube pushes grease (bore butter) into the 2 grooves at the same time.