I put a 5" 3-jaw chuck on my 7x10 Harbor Freight lathe. This is the one: http://www.littlemachineshop.com/products/...?ProductID=2345
You'd be surprised what that little machine will donow! Sure, bigger, heavier, longer lathes are better, but I have worked on both ends of Mauser military and medium sporter barrels this way.