Well, couple things to address in there.
First,
this other thread of mine shows the two lock ring setup. The top lock ring still sets the critical dimensions, the bottom ring allows for exactly how much slop you'd like, and the use of Forster lock rings means the assembly will actually lock, which is neat, given the provided die blocks... don't. That thread will also show you how to repair yours should you ever use it for sizing and have a stuck case, because it'll fail in a real neat way.
I have never once measured runout. Don't own the tool to even attempt the job. Doesn't matter for me, I'm not shooting benchrest, I mostly attend as many one day local PRS style matches as I can and have a ball. My goals are: sub 10fps standard deviation in velocity measured over an entire day's worth of rounds, 0.7MOA or smaller 10 round groups back-to-back, so far away from signs of pressure that I can shoot wet ammo on a 103degree day without the slightest stiffness in bolt lift, produced in such time and quantity that I don't hate every step of the process.
You asked not to be told to select other equipment, and that's fair, we might be able to get you where you want to go with what you have. I gave my M-Press away long ago, but I still get folks PM'ing me about that thread, so I'm sympathetic and try to help as best I can.
- What cartridge are you loading?
- Can we have some specifics, leave out the final charge weight if you'd prefer and you don't hear kernels crunching when you seat projectiles, but can we know the components?
- What platforms, applications, and conditions will the completed ammunition need to perform in?
- How is it performing currently?
- How are you measuring the velocity, and how many rounds do you sample per combination?
...I just scrolled up to see what thread this was in. Sounds like a great topic for a new thread. Make one and tag me?