What may not be clear is that all brass shows the pressure ring, it is the juncture of the case wall and the casehead. Ken Waters measures this expansion, Not to find maximum, but rather to define that he is INSIDE maximum pressures. (See Ken Waters "Pet Loads" for further info)
The very nature of dimensioning requires that the brass be SMALLER than the chamber by as much as .010" If it were not, the brass would stick in the chamber rather than extract. Military brass is often heavier than the civilain counterpart, (7.62 Nato as compared to 308 Winchester for example) Not because the loads are run to higher pressures (as is often told in the rumor mill and other uninformed places) but because the chambers of military rifles are slightly larger and the brass is heavier to prevent case ruptures. The chambers are larger because of the need for the rifle to extract every time, all the time. If you find a civilian rifle that will close on a field gage, then you definately have problems, yet a miltary rifle will close on this gage, if it won't close it needs work.
EDIT: It is the growth of the brass on firing to seal the chamber that causes the pressure ring to form, the case wall expands more than the case head and we are left with the pressure ring
Resizing is the big enemy of brass life. The more dimensional change from a fired case to a resized case, the more the brass moves. That is what causes case seperation, brass flow from the lower case area toward the neck. Usually, the case will have neck splits before it will show incipient seperation signs. Every time we fire a case and resize it it gets harder, it is the nature of brass, it work hardens, and this is why the neck splits. (Generally)
Taking your brass and having RCBS or another maker make a resizing die would probably improve your brass life by about 5 or so firings. It could be greater, I have brass I have fired 40 + times, but am only resizing a maximum of .005", these are high pressure pistol cases fired in Handis at pressures LESS than 13000 psi, 10,000 psi would not surprise me. My new brass is not even exposed to enough pressure to get a pressure ring, and I can't reseat a bullet in some of it with out running it through an expander die.
Pressure is our friend, without it a rifle won't work. It is not a question of pressure, but how much and when. We want pressure, just not too much of it. Problem is, most of the diagnostic tools available to the average reloader will only provide estimates, like Ken Waters, the best we can normally say is that our loads don't cause sticky extraction, don't expand more than a factory load and with a chronograph, don't exceed the velocity of listed loads.
It may be that a chronograph is the single most important tool a reloader owns. If you reload and don't have one, get one. I do not know how to emphasize this more. Clock various factory loading of ammunition using bullet weights you are using so that you know what normal is, normal being not only velocity averages, but how the rifle opens and extracts as well.
Factory ammo tell us a lot. Just think, the plain jane Remington Green Box is used in probably half the rifles in the US. Can your ammo perform that well in so many different guns, produce maximum velocities, good accuracy and not be over pressure in those rifles as well? And don't forget, the ammo does this from below 0dF to above 90 dF. Yes, as a reloader the object is to make ammo that outperforms factory ammo in your rifle, but remember, it is factory ammo that sets the standard we seek to reproduce if not exceed.
