I don't believe you will shoot out a barrel after 1000 rounds from a 300 WM, 4-5 thousand maybe. I have been told that an average life of a 22/250 is about 5-7 thousand. A 223 much longer. As far as barrel material is concerned, a harder barrel will not nessessarily give you more wear resistence. Using your automotive cylinder as an example, they are made of cast iron, not steel. They are not very hard at all but very wear resistent. If there were better materials for gun barrels than they are using today you can bet some one would be using it. As far as a barrel shooting better after 100 or so rounds, If a bore is a little rough it probably will, If its too rough it probably wont without lapping or pollishing. Just my $.02 KN