I am preparing to convert some .308 Win cases to .30 BR. I do have some of the Remington BR brass, still in .308 form, not sure what the neck thickness on that will be but I am almost certain any formed from regular .308 will have a very thick neck.
I do have one of the sets for neck turning on the Lyman case trimmer, I played with it a few years ago and wasn't too pleased with the results.
The chamber cast I did before installing the barrel gives me a neck diameter of .332", so I have been thinking about the easiest/ best /cheapest way to do this operation.
So far the cheapest option is to learn how to make the Lyman unit work.
Next cheapest seems to be buying an inside neck reamer for a Forster case trimmer (I do have one of their trimmers).
Then we get into the Sinclair tools.
I have never had a tight necked chamber before, although I did run into this problem years ago when forming 7.65x53 from .30-06.
Looking for opinions, I'm not in a hurry on this build.
Robert