sometimes, pistol dont shoot

[Nano]

I have a fwb p30 match air pistol.
the other day, when i was shooting, pressing the trigger could not shoot the pellet with the loaded gun, after moving the lever for dry shot, newly I could shoot.
I opened the gun to see if there was some bad piece, but at first sight there was not anything bad, toward time I was suspected that the spring of the hammer was very weak, so increases him some washers, with those washers increasing the pressure of the spring, I solves the problem.
Although the problem has been solved, the truth, I don't understand what is wrong in the gun, can somebody help me?

Thank you,


Nano