Hi Andy,
Lovely SN 501 Swiss Luger !
Is there a chance you could post up a close-up of the "polished" area underneath the thumb safety lever. This area will sometimes let us know if the gun is DWM original factory finish or possibly a Bern arsenal rework.
A photo or two of the insides of the frame well would help as well.
BTW...I have a close cousin of your gun...mine is SN 555...both probably made in the 1901-1902 time frame...when 2,000 guns were made in Germany for the Swiss military.
Thanks, and again...congratulations !
p.s. The take-down tool with the swiss cross stamping is not reported used in Switzerland by collectors...most are thought to have been "marked" later to give the impression of a Swiss Ordnance piece.
Here is a close-up view of the stamping on my "Swiss" TD tool...