Suppose you have an 1895 Winchester in 30-'03...... You could simply use 30-'06 ammo. But say you want to reload and use correct length cases.......You'd likely be hard pressed to find real 30-'03 cases. No worries, just use necked up 270 cases. And that, my friends, is the beauty of reloading. Now, 33-WCF is a little more difficult, but I want one.