Purely out of curiosity - would a 4 stage hand pump be noticeably "easier" to pump a 250 bar gun vs. a 3 stage? Readers digest - when I bought my AA S510 a couple of years ago - it came as a kit from PA and included a Hill MK4 hand pump. The thing works quite well - but is also quite a workout. I've recently become aware of "4 stage" hand pumps and after some googling I (now) know that my hill is "only" a 3 stage unit.