I have what I've just now discovered is an old .22 BSA air rifle. I learned how to shoot with it when I was a kid and I taught my three sons how to shoot with it. There are no markings on it at all other than above the trigger on the left side is what I assume is the serial number "S7787", the stock is stamped "14 1/4" on the bottom, and in front of the loading chamber it has a "2" with "LOAD" below the "2". It's served us very well but the leather piston has now self-destructed. I've seen the tutorial how to make a new one but I'd like to know if anyone has a recommendation for someone in the US that could do this for me for a reasonable charge. Thank you.
Jolly, Not many places here in the U.S. are interested in pre-war British or European guns. One who is likely to have a piston seal for your BSA (and may be willing to work on it) is John Groenewold who can be contacted via https://www.jgairguns.biz/
Your gun is quite easy to take apart and replace the seal if nothing internal is damaged, so I'd encourage you to tackle it yourself.