These are fairly common in the US.
If you can get back issues of the Journal of Lock Collecting (from the American Lock Collectors Association, http://www.alca.us) there was a nice article in the May/June 2003 issue, pages 13-17.
Also, the West Coast Lock Collectors Association (http://www.wclca.net/) had an article in their April 1998 issue of âThe Antique Lock Collectorâ starting on page 5.
These are also briefly discussed in a book âHigh-Security Mechanical Locksâ by Graham W. Pulford, pages 379-381 (and the book is fairly interesting to get just on its own merits).
Another standard reference is Don Stewartâs book âRound Six-Lever Push Key Padlocksâ.
Are there any other markings besides âChampion 6 Leverâ, âMade in USAâ, and âMillerâ? Some of these have patent dates stamped on them, and/or a fancy trademark stamp.
Iâm not an expert on these but the fact there is only one âpin spotâ on the face (just above âhâ in âChampionâ) suggests it was made before 1910.
