Huben All Things HUBEN K1 - Master Thread

I have a 2021 K1 with a 2018 magazine (and matching LW barrel) in it, and there is no noticeable play in it like you are showing. I tried to measure it with the depth function off my calipers, but I'm not picking up anything.

I also still have the 2021 magazine along with the entire barrel holding assembly that bolts to the action (this lets me easily swap between the two barrels, not that I do that much). In that one that is not mounted to an action I can induce a little bit of play in it like you show, but only because there is no other constraint on it other than at the top . It stays firmly in position at the top (with the spring arm pushing down on it) and can pivot out from the bottom about 1.5mm or so - as I do that, I can see that the magazine is moving independently from the bearing, which stays firmly in place. I feel that if I put it up against the action like the other mag currently is, there would be minimal movement.

It looks like you simply have more total clearance in there than mine does. Both of my mags measure exactly 11.0 mm in depth.
 
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there’s also a flat half circle-like piece of black plastic(almost like a spacer)that sits between the magazine and the barrel block.
That piece is there to help guide projectiles as the mag rotates towards the barrel. I expect that without it, jams would be more likely. I don't think it's absense would impact the current issue being discussed.
 
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Thanks for the tips. They are very helpful as I ease into setting up my K1. My barrel and barrel block have four bolts( 2 long and 2 shport). Is there in barrel alignment procedures needed with this model?
The long cap screws secure the barrel block to the action. The lower short cap screws are the ones that are used to align the barrel in the barrel block. There is a procedure that is used to align them, but I've never had to do it yet. Supposedly it is not technically challenging but is fiddly, sensitive, and hit or miss. Gregor explains it in his excellent teardown video at about the 17 minute mark, but does not really show it as he does not actually do it at the time. The video is excellent, and gave me the confidence to work on mine.

If you can't get the alignment back to where you want it, you could always send it off to Kelly at KrazCool for service.
 
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The more I think about this, the more I think @Sergey1972 is correct in that the issue is that your barrel has too much gap to the mag. While I can induce some rocking in my mag/barrel block that is not secured to the action, I get none in the one that is set properly and secured to the action.

Gregor talks through how to set the correct barrel position in that same video. I always use his procedure, but find it is a balancing act to find the best position of alignment of the mags grooves and the gap to the barrel - there have been a few times when I have done it where, when I secure the barrel block to the action after setting things up that the mag won't rotate, which shows that there is an interference fit. I then take it apart again to realign with a bit more clearance. This is something I now check every time I do it, as I have made the mistake of airing up the gun only to find that I had the issue and the mag would not rotate, and then had to vent it and tear it all down - now I check it before putting the gun back together. I have also done it and felt the gun was too loud afterwards, indicating too much gap, so I've taken it down to tighten it up some too.

As a side note, I also have a Western Airguns Sidewinder and go through the same kind of balancing act on it getting the gap to the mag correct. The Sidewinder mag also has lands and grooves, but there is no way to see if there is alignment with the barrel in it, so I'm sure it almost never happens - in fact I just remembered it can never happen because the barrel has four grooves and the mag as six . . . so maybe the alignment is not as significant as Gregor thinks . . . I don't really know. At least on the Sidewinder the barrel can be set easily without degassing (but I still think the Huben is the better gun).
 
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