These were used in the early 1900s to make crocks up to 60 gallon size in the Medalta Potteries factory in Medicine Hat, Alberta, Canada. The metal barrel was fitted with a wooden base, then lined with paper. Then the clay was rolled up the side and surface finished. The barrel was then dropped and the crock removed.
To potters, stonewares are simply high temperature, non-white bodies fired to sufficient density to make functional ware that is strong and durable.