heres a 9mm pumper, 95 fpe or so https://www.gatewaytoairguns.org/GTA/index.php?topic=203433.0heres a 19 fpe single stroke https://www.tapatalk.com/groups/yellow/viewtopic.php?p=1475232#p1475232theres been many other powerful pumpers like bobs millenium , but none ever went to production that im aware of //a large 880 with metal pump handle would be awesome , maybe 25 cal or 30 cal
Not exactly what you described but I converted a Crosman 362 to 25 caliber. It's putting out around 17 fpe with nothing but a barrel swap and an enlarged transfer port.