Making sure the loaded cartridge goes properly into the chamber is absolute basic reloading. Reloading shouldn't continue until it is known that teh cartridges will go in.
At one time, after loading one cartridge, I would go up stairs and tell my wife I was going to go outside with my rifle and chamber a loaded a shell. I would tell her there was a slim, remote chance it could go off. But not to worry, it would be pointed at the ground.
Now, this thing they call modernization has caught up to us. If a big rifle shot went off now, in the same yard, I would quickly be surrounded by more police than I thought existed in the area. Can't chamber a live round now!
After resizing the first case, it should be tried in the chamber. If the rifle is of the old Mauser type, the bolt should be removed, the sized case fitted in the bolt face and the bolt returned to the rifle. You should feel no more resistance than maybe a slight touch as it kisses the shoulder.
OK, the case is properly resized, but this does not guarantee the loaded cartridge will go in! Some of us will take a fired case (same rifle, of course) slightly squeeze the neck,so a bullet will go in the neck finger tight. We will push in a bullet a bit in the neck, then chamber that dummy load, using the method described, if it is a Mauser type action. We will slowly close the bolt, which will push the bullet into the case, as it hits the lands. Now, the dummy load will touch the lands, so if that is what we want, we will set the seating die to this setting. Most likely this will not feed through the magazine, so if we want to work with the magazine, we will try it and adjust it in until it does work through the magazine.
We will now set the seating die to seat the bullet at that over all length. I hate to say so, but if the cases are going to be crimped, or are accidently crimped when we didn't intend it, the loaded cartridge may still not go into the chamber, as it should! This is because the crimping may force the neck back a bit, thus expanding the shoulder. Some cartridges are much worse for doing this than others. For example, this will likely not happen with a 30-30. but could easily happen with a 243 Win.
So, the best, safest way to know if the loaded rounds will chamber, is to make the first "loaded" round a dummy; no powder and preferrably, no primer. If this chambers satisfactorily, you can go ahead and load up.
Some one on here may point out that I did not mention what the book says is the over all cartridge length. You are right, I did not. And that is because I couldn't care less what some loading book says my coal should be. My cartridges are designed to fit my rifle!
