1) turn off the hop-up (spin it down to 0, no hop, or spin, or whatever you like to call it). Shoot.- GO -> the bucking's the problem. Buy a new one. Silicone would do good (suggest Guarder or Systema)
- NO GO -> GOTO 2.
2) take the gun apart. Take the inner barrel out of the HU chamber. Check, whether the bucking's not damaged (torn or something) in the area, throug which BBs enter the barrel.
- IT IS -> buy a new bucking...
- IT ISN'T -> GOTO 3.
3) put some silicone oil on the bucking. JUST A LITTLE. It'll mess with the hop-up system, making it slippery and so on, but after shooting out about 2-3 hi-cap's it'll be back to normal. Check.
- GO -> problem solved
- NO GO -> the bucking's NOT the problem -> buy a new chamber... I recommend Deep Fire. Altough that's a 9/10 possibility, it may always occur, that the problem was the mag, so before you spend your money (altough buying a DF is a good option anyway) try a different mag. AND NOT A MID-CAP. Try it with a low- or real-cap.
Heh... I'd give you more options, weren't it for the lingual barrier.
Oh, and try getting a new.... errr... what the hell it's called in english? You, know, the tiny little thing you loose each time you take the bucking off... I mean this guy:
CLICK <- GET something lite that. It makes your HU work a little like BAX, making the BBs more stable.
Anyway - what IS it called?