I believe it's actually a one stroke pneumatic. looks to be an fwb 65. they were also made left handed. I had one years ago and my lh bil still shoots it from his 'chair' at the 'old folks' range over in the Villages, FL. awesome olympic grade airpistol. treasure it.
It’s a recoilless sledge system like the 300s. I might be messing up the technical operation of it but they were Olympic air pistols in their day. It’s great backyard spinner practice. Capable of one hole accuracy at 10 meters.