@ Exorcist_86: I have not changed the hop-up but the bucking, this small plastic piece that looks like a piece of electric wire that push the hop-up rubber down the hop-up chamber. I've changed it by a H hop-up bucking. The advantage is that it should put an equal pressure on the rubber each (upper) side of the BB. I hope I am clear enough in this explanation. After having tried the unicorn today during a skirmish, I am fully satisfied with the hop-up.
@Greatwatermelon: It seems to me that your front set, the upper and lower handguards are not fitted properly. This is certainly the reason