These tools were owned and used by George Wagner who was a cooper for the Old Dutch Brewery in Findlay, Ohio, USA. Mr. Wagner emigrated from Germany, (where he learned his trade) by way of Argentina, Altoona, PA., Toledo and Findlay where he started work at Old Dutch in the 1940’s.
Originally a hole would have been bored, and then a pod auger was used to ream the hole to a taper to allow a tapered stopper or plug to be tightened into the hole. These bung borers shown were an improvement in that they carried out the process in one operation.
Cask Sizes

Pin 4.5 gallons
Firkin 9 gallons
Kilderkin 18 gallons
Half Hogshead 27 gallons
Barrel 36 gallons
Hogshead 54 gallons
Puncheon 72 gallons
Butt 108 gallons
Tun 216 gallons

Image: Whit McLeod

The name and size of casks varies with the contents, namely, whisky, beer, and wine and also casks for dry goods. British casks of wine used the following sizes: Gallon, rundlet, barrel, tierce, hogshead, (firkin, puncheon and tertian) (pipe and butt) and tun.
Wooden kegs usually had two tapered holes, one for filling, a tapered hole in the side (middle) of the keg and one for emptying, a tap hole through one end near the rim.