Calif-Steve, re: The Dealers Warehouse in Modesto, California. Are you sure they have new No 4 barrels?
Nobody has seen a new No 4 barrel in the UKicon for a long time now. Because of this, Armalon in UK have recently begun to make new No 4 barrels, and they also sell No 4's which have been rebarrelled by them. Given the problems which DIY re-barreling might entail (I don't understand all the technicalities in the posts above) buying a re-barrelled No 4 from Armalon would be an attractive proposition for someone in the UK.