I've been watching a few Youtube videos on reloading and I'm interested in finding the C.O.A.L for my Remington 700 5R in .300 Win Mag. I noticed that the videos on Youtube that address this usually require you to take a fired round from the rifle you're working on and set the bullet you want to use in the case mouth. They say that you want a fired case so that the bullet will be able to easily slide in the neck when pushed from the back. Well, I've tried four different spent csings that I've shot in my rifle along with three different bullets and not one of the bullets falls through the neck easily. In fact, they barely sit in the neck opening at all. Am I missing something?