Fukert patent locks, sometimes called "crown" locks. Gun cocks on opening, unlike most exterior hammer guns and has a safety. On my double it is a simple thumb safety. The Fukert patent has been used by many others. In recent years, a British auction house had a group of eight or so Fukert patent double rifles. Quite expensive and did not sell in at least the first go around. Vestidual [sp?] hammers can be individually cocked in the normal manner.

http://www.bakercollectors.com/