Huben K1 problem - buzzing and dumping air

[Steyr]

I have had a Huben K1 for the past 4 years (2018 model) and taken it apart a few times to sort out leaks and even rebuilt the regulator so I know my way around the gun.

However, recently, when I shoot the gun (Reg 16mpa, Air cylinder 240bar, power adjuster 15 clicks from closed), it buzzes continuously and dumps all the air.

I recall reading this may be caused by an indexing issue and is caused by an improper regulator and delivery valve adjustment. I have played around with the reg pressure and power adjuster settings and I always make sure the cylinder pressure doesn't go down below the reg pressure, but whatever I try I always have the same problem.

But, I can't for the life of me work out what is the problem. Any ideas where to start?

 

[Pale_Rider]

I would start with the air mag index parts

Have you changed the seals in that area?
53 and 55

 

[AlanMcD]

I ran into a problem with mine where it started to jam up on me. Kelly at KRAZ Cool airguns told me that the index spring (part #45) can get weak after about 20,000 shots or so (which is right about where mine was) and that can lead to indexing problems and jams. I changed it out and I was back in business with not a single jam in many thousands of more shots.

I don't know if that is exactly your problem, as I don't recall if mine buzzed or not. It would shoot OK for some shots but then hang up and dump the reservoir after a shot at increasing intervals (and of course it made a lot of noise doing that).

 

[Steyr]

hey guys, thanks for giving me starting points to investigate. i suspect you are right and its an issue with the magazine indexing mechanism. one thing I have noticed is that the magazine release arm is not as stiff as when i first brought it. also i can spin the magazine freely clockwise even when the magazine release arm is in the down position, whereas when i first had the gun this was not possible.

 

[Pale_Rider]

The mag spinning freely *when the arm is down should definitely not happen lol. Now that sounds more like a problem with the magazine release area (parts 44 through 50). Either the index spring (#45) or the arm tension spring (#46).
I would order parts 45,46(springs) and 53,55(o-rings). Kelly (Krazcool AG) has parts in stock and for good prices.