Years ago a friend of mine made and fitted barrels and some other parts for two Palmers that were damaged beyond repair. He also made machined brass cases with an offset hole in the case head where he inserted an RWS .22 blank as a primer. I have a couple of his prototype cases around here somewhere.
My friend made the stuff for a guy who supplied movie props. One of the Palmers was used in the filming of the TV miniseries North and South.