Hi I've had a 1377 and 1322 for years that are the old type with the hammer knob at the back the 1322 I've converted to air to run of my raped bottle when it got down to 1000psi with steel breach and scope and stock like rat catcher and the 1377 steel breach of a falcon fn19 flat top
Piston stock scope and silencer then everything had to be bigger but as you know now bigger is not all was best and you have a limit on pistols the valves in them had spacers in or a loneg PTFE inlet valve taking up volume witch I took out then . but you have to much on standard barrels and the pellets gone time the rest of the air comes out . so know I've put a small spacer in to reduce volume so now with ftp 7 pumps 5.25 flb and you struggle to pump it more . there was one of these that had a different valve witch I sold way back but made the trigger much better it cocked when you pumped it and the valve split to release pressure has any one got one or seen one . any way I've found out now the pump has a mane part in the workings and I do not want to be pumping 20 + times I've a bull worker for that any way the first write up was good