I asked Ed that very question back in October. He said about a year, but is only working on custom orders, no stock work. If you have been waiting more than a year, I would call him.
As to why wait, well, you don't have a choice, frequently. There is more demand than supply. There are only but so many sets of equipment out there specifically designed to do this work, most from WWII. If you want to get setup to do this work using modern equipment such as Rice has, it is going to be very expensive and require some pretty good engineering and machining skills to setup the equipment to meet the needs of barrel making. Even at that, the market just won't support much more than a one man shop.
The old joke is "How do you make a million dollars building guns? Start with two million."