Originally Posted By: redoak
I have several Birmingham boxlocks that were originally proof marked in the mid-1930s with barrels and actions that I believe were supplied to the trade by Joseph Asbury. They are all marked under the barrels with a small "J.A."

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=458496

I had a Field SLE (Baker ejectors) that has "J.A." stamped on the underside of the barrels as well.