For what it\'s worth - I bought mostly 10-22 takeoffs from rimfirecentral.com. I advertised and also bought barrels offered for sale. I ended up with 2 Springfields, 1 Sears, 1 Winchester and 8 Ruger 10-22\'s.
Turning the barrels while holding size and finish is not a lot of fun. I did mine between centers with a dog (real old school) and by using a very sharp tool and light cuts did okay. There are several posts here bemoaning the turning of barrels and a couple of good approaches. I also left the barrels long until after they were chambered and fitted to the barrel plate. I used the method first shown by Cutter that uses wedges and barrel tendons to secure the barrels. While the barrels are matched to a location they actually fit and headspace in any hole. Chambers were reamed using a Clymer reamer that I have had forever and controlled for depth using standard headspace gauges and a depth mic.
After the chambers were completed and the extractor groove cut using woodruff key cutter - the barrels (12), were indexed in my mill, cut to length and hexed on the ends. Using this approach there was a recovery path if something went amiss in the machining of the chamber end. The barrel could be cut off and the end recut while still maintaining the proper overall length.
Hope this helps, your mileage may vary.
nitewatchman