I was chasing Gustav Kersten( DRP No. 141334, 1902 ) and noticed that Emil Flues had a lockup that looks to have been loosely based on Gustav Kerstens( I think it was in 1914 but can't put my finger on it- Model One-Barrel Trap Gun-original bolting system):

http://www.google.com/patents?id=wJJfAAA...p;q&f=false

http://www.google.com/patents?id=4ONjAAA...ues&f=false

Also here's a rib advancement by Emil Flues:

http://www.google.com/patents?id=HN8ZAAA...ues&f=false

These appear to be on single tube guns but were either of these patents or both used on O/Us? It appears that the difficulty in reloading kept O/Us from taking off.

Kind Regards,

Raimey
rse