John, I look Steve's web and the sidelock you mention is absoluut not a new made Francotte gun. True that the Netherlands not have a proof house. I am familiar with the Liége proof house records and as far as I know there are under the name Francotte NO guns prooved in 2008 and 2009.
If you can give an example of 1 gun registred in the Liége proof house register under the name A.Francotte please show us and if you can I excuse myself for all members.