Honestly tho, theres just no reason to put a guys barrel on a shelf for 6 months. It takes an hour to do a simple chamber in a jamnut barrel if you're set.up for it. When I chamber a pipe, I typically try to do a few that day regardless of when they showed up, because it saves me the time to setup the fixtures. Hes not asking for 30 hours of labor by tomorrow morning.
Some Smith's just sit on stuff to add a mysterious feel to their work I think. Cmon. Ream, chamfer, check bolt depth and take the mans money. Now, if it's a dead blank and he wants threads, shoulders set, and muzzle threaded, that's maybe a little different but still not a huge project
Edit: dont take it to a machine shop. That used to be a good idea for mundane detail stuff, but these days, the only shops in business are high production cnc facilities where guys spend all day pressing "start" and "stop". Very few of these places even have "dads old southbend" in the back room anymore, and the ones that do wont want to run it for your gun projects