Hi John .. the .22 washer I destroyed ... see post above ... looked just like your red one, mine was red and quite hard. The Webley pictures are fascinating as they even show that the washers when made had the slight depression factored in that takes the raised ridge around the barrel end. I had assumed that the action of the 'turn bolt' pulled the raised ridge into the washer material to form an effective seal.
Now ... where do I find 4mm thick red fibre washers or sheet .....
Thank you.
Mind you, my .177 is still sealing perfectly on a 2mm thick washer on top of the brass carrier.
Cheers, Phil