They say every x2 pumps puts one shot back in your gun, I mainly use a mates bottle but do have a Hills pump I use occasionally but I can tell you it takes me 150 cycles of the pump to get my gun from around 90bar to 190bar (but my gun holds 400cc of air) and when you get to the 100 mark it starts to get harder. The only thing in my favour is I am 6ft 3 and 19 stone so using the pump is not that difficult but it does take effort.
Hope this helps
Coney.