.223 case neck?

[pelallito]

I have cut off some .223 cases, ran through the redding F L die with .30 cal expander. Then trimmed to final length and chamfered inside and outside of the mouth of the case.
I was going to try to outside neck turn the cases and my .30 cal pilot for my sinclair? trimmer does not slip into the case neck. Using my caliper, I am getting a .305/.306 ID measurement. The pilot is about the same. I have used both the tapered Redding expander and the regular expander without any measurrable change.I lubed the case neck with the Imperial neck lube and it did not help at all.
I am also seeing this in some .221 fireball that I converted, but I don't expect that those will have as thick neck walls.
Does someone know what the forster/rcbs inside neck reamers OD is?
I am going through these as if I were preparing cases for a BR rifle since I am making them for my first which will be a bolt action single shot.
Any suggestions and advice appreciated.
Thanks,
Fred
Found out that the reamer is for fired brass that has not been resized and cuts .311. That is too large for what I am doing. I will make a smaller diameter pilot/mandrel that fits this neck ID and my tool.
I need to find a reamer for the dreaded doughnut, maybe.
Any suggestions and advice appreciated.
Thanks,
Fred