Hi Garvin,
you've triggered some pleasant memories for me!
I used to play around with a Falk when I was a boy. Not sure if it was a mod.30 or 60,cant remember.It was a smallish gun and It had a leather breech washer and was a smooth bore in 0.177.
Sadly I don't have it any more.
Thanks for posting the info on the Falk 90, very interesting read.