This is my "big twenty" in action. A day of calling after a good snow fall.
It's fairly basic setting up your brass. I use a Redding .22-250 "full length bushing die". The necks need to be reduced using 3 different sized bushings, ( you can't reduce the necks from .224 to .204 with one size bushing) the body does not get altered. The shoulder will fire form slightly after the first firing. My chamber is a "tight neck" and requires neck turning the brass, among other things. I'd be happy to give you all the details, if you so choose to go with it.
Personally, for a Calling rifle, hands down, I prefer the flat trajectory offered by the 40 grain bullet vs. the 55 grain bullets slower velocity/ rainbow trajectory.
Greg is a busy guy, a year is about right and he's not cheap, but you get what you pay for. He has the reamer too and will build the chamber around the "dummy round" you set up. I know he was moving his shop, among other things and I got caught up in it with my last build, it took 18 months. Pretty sure that's behind him now, should be smooth sailing.....
Throat wear is not an issue, certainly not "chasing" the lands. Most always, it's a single shot fired and off to the next stand.