Yes, the original owner of TRU BOWN is no longer in busines. I bemoaned the fact a couple of years ago and he sent me half a case which is close to a lifetime supply. Very gratefull. It's curently available again.
Finishing. I really hate to fool with afterusting. When browned, I wash the barrel with water then apply a saturated solution of sodium hydroxide. This stuff is extremely caustic so wear gloves. I know you can use baking sod and so forth, but the chemical fact is no acid is left after this stuff. Any online chemical co. sells it and a bottle is a lifetime supply.
Wash it off. Rub the flats with 4-0 steel wool, staying off the corners. I then apply enough heat to the barrel, working one end to the other, to drive off all moisture. Then apply oil. and rub again with the steel wool. (Oil of any type, makes things less abrasive then water.) Wipe off he oil and you're done. Clean the barrel with oil in fact.
Wipe over it the next day with a clean cloth and you get a pretty clean cloth. Anything else and, lets face it, you get rust on the cloth. Putting varnish, wax or linseed oil on the barrel will supress the rusting for a short while, but it will be back unless it's neutralized or (most likely) has used itself up.