I've got an old friend who he and his wife shot competitive skeet heavily for thirty years . When they got out of it they had four hydraulic 9000's and two hydraulic pumps . They had the 12 and 20 connected to one and the two little guns connected to the other pump . I was actually surprised when he told me how much he liked the 9000H for the 410 .

It's not the cylinder - the pump looses pressure when it warms up. It goes from 700psi to under 500psi at around 150 shells. It's still up to speed anything over 500, but under it starts slowing down. It goes very slow on the down stroke. I'm not sure, but believe if the big nut on the pump is removed a washer can be installed to put more pressure on the spring. It's kind of like me - getting old and slow the more I do.