My package from Manson arrived last week....Jessica is fantastic to work with and they are an overall high-class bunch of people.
My first challenge was in overcoming the little voice that kept shouting "Do 'em all! Do 'em all!" I finally countered the voice by smacking myself in the head with the hammer handle I use to remove sideplates and reminding myself that this was the first time I've done this and if it turns out to not work well I would rather screw up just one gun and not four. Sometimes I'm a bit hard headed.
The second challenge is that it's been over 110 degrees several times this week and my garage simply has not been a fun place to be. I set up a temporary workspace in the spare bedroom. This "gunsmithing with air conditioning" thing may catch on. A remodel/reorganization may be in order....
The third challenge was in finding a handle for this itty bitty 1/4" reamer because I was waaaay to smart to order one when I ordered everything else.

My Dad's Craftsman tap and die set from the 1960's provided a tool holder that worked. The proper tool is in the shopping cart in another tab as I type this.
Once the preliminaries were out of the way, I lubed up the reamer with the Viper Venom cutting oil from Manson and went to work. (Side note: I bought the quart jug of cutting oil. At the rate I used the oil on this gun, I estimate that the quart will last me approximately 187 years) The finish reamer worked beautifully: no chattering, no sticking, just a nice smooth shave.....right up until I ran into challenge #4.
Between the height of my temporary work table, the lighting in the room, the size of the reamer, the size of the puddle of cutting oil, and the recessed chambers
I couldn't see when to stop. I ended up hunched up like the proverbial monkey with a football using the camera-zoom function on my phone as a magnifier to watch the last little bit of cutting. I wanted to just barely kiss the face of the cylinder so that I didn't change the headspace. It worked, but next time better lighting is definitely in order.
One empty case at a time was moved as I went around the circle so that the ejector star was always supported. After cutting the second chamber I was able to recognize the change in the "feel" of the reamer when it stopped cutting. (I hope that makes sense) Every chamber was done twice just to ensure that the feel of the reamer was the same in all of them.
So what was the final outcome? It truly was a "shave" and I never saw any real chips or swarf....just what looked like dirt in the oil. After all the chambers had been touched twice the cylinder/ejector star were cleaned out with brake cleaner and the pin gauge measurement routine was performed again. The data came out exactly as I was hoping for: the inconsistencies in chambers 3, 4, and 5 were gone and now the graph looks much more satisfying. Additionally, fired cases that used to require a push now drop into the chambers with an audible thunk and headspace on the rim instead of getting stuck part way in.
I'll do a range test tomorrow with every brand of .22 LR that I have on hand and report the results tomorrow evening.