ummmmmm... The lock on the Feather gun is about as German as it gets. In fact, it's really what the Siler "should have been." You can use a Siler kit as a base to get the Feather lock out of it, mostly, but you're going to have to do a lot of reshaping and also a couple of replacement parts. It's not clear whether it's a German import lock or an American-made copy.
I'm pretty sure there are pictures of the lock 'out there' somewhere. I might have some, will have to go check.