Here's a question because I don't know the answer. Did the whiscombe rifles stroke number i.e 55, 60, 75, 80 refer to each individual piston's stroke, or combined stroke?

The JW80 was a genuine 30ft-lb rifle by some accounts. I'm not sure that would be possible with a combined stroke of just 80mm. So was it 80mm per piston? Which would give 160mm total stroke!
Hopefully someone more knowledgeable will chip in and correct me