The OP is asking us to report
"any issues or problems with Huben GK1"....
Well, yeah, I would like to report TWO issues or problems with my Huben GK1:
Somehow, whenever switching from shooting my regular PCPs to shooting with the GK1,
the Huben causes some kind of problem with the pellet tins.
They go from "full" to "half-full" to "empty" at an alarmingly rapid rate.
I can't say I'm not concerned.
(I'm sure it has nothing to do with the flawlessly working semi-auto function of this pistol.)
The other issue or problem the GK1 is causing came out after a good while of owning the gun. I discovered this problem when I took it out for its first hunt.
The GK1 (particularly with a dot scope)
causes speedy death at a devastating rate, even when used offhanded (a skill at which I'm still a beginner).
(I'm sure this problem has nothing to do with the GK1's
precision and
nimble handling due to its size and weight.)
I'm pretty sure both of these issues or problems
have no solution (other than getting rid of the gun).
And that won't happen anytime soon.
Matthias