Huben Huben GK1 .22: A Beginner's Journey to a DIY Mini Carbine

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Another little side note. If you are going to be tinkering on a GK1, highly recommend getting a hex key set, and not a fold-out set. I am constantly using smaller metric units, not only just on the GK1, but on mounting rails, optics, just about anything. It is so convenient to have a set of handled individual hex drivers. I picked up this set on sale for like $12 at my local Harbor Freight.

 

[Navig]

Clean that barrel

Super appropriate for @weevil to have dropped in to my thread!

Now that we are getting this dialed in to a working weapon if not yet a mini-carbine, it is time to clean the barrel!

My experience with the @weevil method.


Picked up the control rods from Amazon.

2 Long hollow tubes, one slides within the other:

Took some kitchen twine (I figured it’s sturdy, temperature resistant, resistant to oils). Made a noose. Solidified the neck with gel Krazy glue.

Added a small column of gel Krazy glue into the end of the yellow rod, and rammed the twine noose into it, and then packed some more Krazy glue in to make sure it was good and stuck.

Here I tested out the action of the system. After a few go's, I knew it took 3 cm of push to properly deploy the cleaning patch.

1 inch gun cleaning patches from Amazon.





And here I am deploying the method on my GK1--.22, also works for .25.

First pass I loaded the patch with Ballistol.

Then I put in clean patches until the patches came out clean.

Also tried these cleaning pellets. They come out superfast and loud, and bounce off the target. I can’t really comment too much on their efficacy as I had already cleaned the barrel.

 

[weevil]

Clean that barrel

Super appropriate for @weevil to have dropped in to my thread!

Now that we are getting this dialed in to a working weapon if not yet a mini-carbine, it is time to clean the barrel!

My experience with the @weevil method.


Picked up the control rods from Amazon.

View attachment 442537





2 Long hollow tubes, one slides within the other:

View attachment 442538








Took some kitchen twine (I figured it’s sturdy, temperature resistant, resistant to oils). Made a noose. Solidified the neck with gel Krazy glue.

View attachment 442539






Added a small column of gel Krazy glue into the end of the yellow rod, and rammed the twine noose into it, and then packed some more Krazy glue in to make sure it was good and stuck.

Here I tested out the action of the system. After a few go's, I knew it took 3 cm of push to properly deploy the cleaning patch.

1 inch gun cleaning patches from Amazon.





And here I am deploying the method on my GK1--.22, also works for .25.

First pass I loaded the patch with Ballistol.

Then I put in clean patches until the patches came out clean.

Also tried these cleaning pellets. They come out superfast and loud, and bounce off the target. I can’t really comment too much on their efficacy as I had already cleaned the barrel.

Many thanks for providing the video demos! By coincidence, I cleaned mine yesterday…

 

[Nutcracker]

Are you using this method to keep from pushing stuff/lead in the cylinder? Today was the first I cleaned my .22 with over 6000 shots. But I just used a rod & swab lubed good & every couple of times after removing the swab, I would fire the GK1 to blow it out.

PS nice video.

 

[Navig]

That's my understanding. I don't have a cleaning rod. I've never cleaned a barrel before! I do have some sort of pull through cleaning kit somewhere, but never disassembled an air gun before (until recently--my most recent air rifle is an AEA, so yah, anyone who owns an AEA knows how to take it apart). But prior to purchasing the GK1, I definitely wondered how to clean it if you can't remove the magazine. Which is how I came across @weevil's thread.

Honestly, this makes cleaning an air rifle so easy and actually kinda fun. Immediately after making this video, I went ahead and employed the same method and cleaned out all my other air rifles. Benjamin SAM, Hatsan Bullmaster (of all my air rifles, this is the only one with a bolt catch), AEA HP SS+. No worries about disassembling, or figuring out how to keep the bolt open. Just insert, deploy, pull out.

Yah I just posted that. Insert, deploy, pull out.

At some point in the future I plan on disassembling my GK1 just for education purposes, but GK has a very extensive video on that.

If you have a cleaning rod, I suppose you could also chase it out with one of those cleaning pellets. A stiff rod also--you would probably need to carefully mark your distance so as to not extend past the magazine. In the GK video, he mentions that if you go too far you will hit the firing valve.

 

[weevil]

Are you using this method to keep from pushing stuff/lead in the cylinder? Today was the first I cleaned my .22 with over 6000 shots. But I just used a rod & swab lubed good & every couple of times after removing the swab, I would fire the GK1 to blow it out.

PS nice video.

That’s why I do it that way. The barrel gets very greasy. I assume it’s migration of the grease from the action. I don’t want to push that into the interface between the action, magazine and barrel. Every few times I clean, I also clean out the mag chambers with a qtip.

No doubt, other methods are fine too. I just find that once you’ve got the dual rod configured, it’s very easy and fast (10 min) and provides the assurance that you’re cleaning it in the traditional fashion - from action to muzzle.

 

[Nutcracker]

That’s why I do it that way. The barrel gets very greasy. I assume it’s migration of the grease from the action. I don’t want to push that into the interface between the action, magazine and barrel. Every few times I clean, I also clean out the mag chambers with a qtip.

No doubt, other methods are fine too. I just find that once you’ve got the dual rod configured, it’s very easy and fast (10 min) and provides the assurance that you’re cleaning it in the traditional fashion - from action to muzzle.

When you remove the receiver endcap, degas, and remove the striker and valve, you can access the bore from the rear. Is there any reason you could not clean it this way? You could easily clean from the breech, which most prefer. Or is this a bad idea? Is there an Oring or something there you might mess up? What I am getting at would not be a complete disassembly. I did not think pushing stuff from the muzzle back to the breech into the workings as I did was a good idea. I probably will adopt your method.

 

[Nomadic Pirate 66]

I'm just shooting felt pellets out of mine, couple soaked in Ballistol then half dozen dry.

I know it's probably not Ideal, one day I make an effort to use a rod

 

[Nutcracker]

I'm just shooting felt pellets out of mine, couple soaked in Ballistol then half dozen dry.

I know it's probably not Ideal, one day I make an effort to use a rod

Yeah, but it is easy.

 

[weevil]

When you remove the receiver endcap, degas, and remove the striker and valve, you can access the bore from the rear. Is there any reason you could not clean it this way? You could easily clean from the breech, which most prefer. Or is this a bad idea? Is there an Oring or something there you might mess up? What I am getting at would not be a complete disassembly. I did not think pushing stuff from the muzzle back to the breech into the workings as I did was a good idea. I probably will adopt your method.

I’m of the mindset that if the gun is shooting so well, as it is, I don’t want to mess around with the mechanics in the action. I don’t even remove the moderator with my method so it’s right back to shooting at the same poi after 5 or so break-in shots. The cleaning pellets may be fine, but it begs the question as to why anyone cleans with a rod and patches. I just figure that shooting little pads at very high speed isn’t as effective, but maybe I should try it.

 

[primaz]

If you are just shooting pellets and you wash and lube them, is there really a need to clean the barrel? I have other friends and even an air gun tuner say that they never have cleaned their barrrels and the gun's accuracy is unchanged. If you shoot slugs then I could see more of a potential reason since the Huben GK1's barrel is not really designed as slug barrel?

 

[sactargetshooter]

If you are just shooting pellets and you wash and lube them, is there really a need to clean the barrel? I have other friends and even an air gun tuner say that they never have cleaned their barrrels and the gun's accuracy is unchanged. If you shoot slugs then I could see more of a potential reason since the Huben GK1's barrel is not really designed as slug barrel?

According to Huben, the newer K1 barrels are actually designed to shoot pellets and slugs (https://www.hubenairguns.shop/products/barrel-for-huben-k1). *If* we assume the GK1 barrel is a shortened version of that of the K1, then it is also designed to shoot slugs.

I am about to test some AVS slugs, we will see over the next week or so how the GK1 shoot .223 AVS slugs!

 

[primaz]

According to Huben, the newer K1 barrels are actually designed to shoot pellets and slugs (https://www.hubenairguns.shop/products/barrel-for-huben-k1). *If* we assume the GK1 barrel is a shortened version of that of the K1, then it is also designed to shoot slugs.

I am about to test some AVS slugs, we will see over the next week or so how the GK1 shoot .223 AVS slugs!

There are many discussions about slugs and the GK1, I only paid attention to the .25 and know that it is crucial to use a .254 but the more I read, the more I am inclined to stick with pellets as this is still more of a pistol even though it has the power of some rifles so for me I think I am going keep shooting pellets and leave the slugs to my slug rifle designed for longer range and bigger caliber to hunt. I am certain there were posts explaining the best slugs for the .22 GK1

 

[Nomadic Pirate 66]

Unless I find a solid with big Meplat bullet that works I will stick to pellets on my Huben pistols

 

[Navig]

Optics Part I

Obviously, optics are a huge point of discussion, hence the entire forum devoted to them. I am about to tread into deep deep water, and here my inexperience is definitely going to become apparent. For my first look at optics on the GK1, my goal was simple. Let’s get something on there besides the iron sights.

The dovetail mount on the pistol only extends down the front ¾ of the pistol. This introduces several problems. For mounting a Red Dot sight, it feels a little too forward. I don’t know if there are functional problems with mounting a Red Dot sight slightly forward, but it does make focusing on the red dot a little more difficult and makes the field of view within the confines of the rim of the optic smaller.

Also, it is a dovetail mount. Most optics are going to be based on a picatinny mount. Or Red Dot pistol specific (the most common footprints being RMR and Docter).

Once you add an optic with magnification, the forward mounting rail really becomes a problem. Magnified optics have a very specific eye-relief distance--that is the distance that your eye must sit behind the lens. If your eye is not at that distance, then you see nothing thru the scope. Having the scope too far forward leads to very awkward shooting positions, with you essentially kissing the pistol grip.

To get start on mounting optics, I threw on this dovetail offset adapter I had laying around, to try and move the optics backwards.

And the first thing I threw on there was this pic rail mount cheap Walther red dot. It’s pretty fun and plenty accurate. As mentioned above, I did run into the Height-over-bore issue with close range shooting. Now that I look at the picture, it’s pretty obvious as the scope is sitting quite high due to the adapter.

If I were to keep the red dot scope, I would develop (or just purchase from Huben3dparts) a rear mount low profile adapter.

But I decided against keeping the red dot for a few specific reasons: I am lazy and have older vision. I found that when I have to zero a red dot scope, at any useful range, I could not make out the impacts on my target. I would have to walk over to the target to check it out, maybe even take a picture of my target, as the target paper filled up with holes, At one point, I tried to hack the situation by positioning a spare Ring camera I had around pointed at the target, but then I was constantly having to check my phone to find the POI.

So I quickly changed out to a ranged scope (Bugbuster side parallax), I could fire-adjust-fire, no need to walk over--as long as I put it somewhere on the box.

I like the idea of a red dot--super quick to put on target. But also perhaps since I’ve used scopes from the start, and scopes with close focus parallax adjustment (UTG Bugbuster and Hawke Airmax Touch), I prefer to have magnification. I probably won’t even revisit this, as I don’t own any RMR mount optics, and don’t really have any plans to, and there is a great inexpensive product out there already.

I will however, develop a dovetail-to-picatinny rail that will extend all the way to the rear of the pistol (and beyond).

 

[Navig]

The 3D Printer!

Woohoo, got a clean pistol, shooting ready, able to put pellets on target. Time to push forward in to making it into a mini-carbine. And that means 3d Printer Time.

My printer: Creality Ender 3 V2; the starting printer for many people, purchased on sale that last Amazon Prime Days. It has the classic upgrades: upgraded bed springs, PEI flexible magnetic print plate, CR Touch auto leveling, 3d printed cable management, Capricorn tubing, replacement fans.

My choice of PLA plastic: Inland PLA or PLA+

I have NO formal training in 3D design, so everything is basic, and I will be happy to explain things as much as I can. Out of respect for the folks that are professionally and commercially 3d printing parts for the GK1, I will generally not directly post my .stl files. However, my design work is super basic and easy to work out--I’ve only been doing this for several months. If I can learn it, you can too.

My 3d design work was all done on Sketchup Pro. Probably not at all a respectable tool for 3d printing work, but that’s what I use. It is super intuitive, and there are so many tutorials, you can pretty much just google your question and find the answer.

You will have to pay for Sketchup PRO version to get use of the Solid Tools, which I found were invaluable. The most common process requiring Solid Tools is creating screw holes through complex and/or layered shapes. With Solid Tools it is as simple as 1) Make sure your base shape is solid 2) Create a baton in the desired diameter of the screw hole 3) Place the baton where you want the screw hole 4) Solid Tools--Subtract, and boom you now have a screw hole thru your complex multilayered curved beveled piece.

Occasionally, I did have to employ the trick of scaling up/down. (Some of Sketchup’s rounding tool’s math doesn’t work with mm sized numbers). So I created in centimeters, and when done, scaled the whole piece down by /10.

And finally, if you wish, you can contact me for any of the 3d printed parts I put out in this thread. I will be happy to print them for you--but understand I am not a retailer or commercial printer. So price might be a little more than you might expect, and also I don’t have much of anything “in stock” so it will take some time. Some of these objects are 8+ hour prints (if nothing goes wrong), and the Ender 3 is not a speedy machine. They will also be printed in PLA or PLA+.

 

[sactargetshooter]

Optics Part I

Obviously, optics are a huge point of discussion, hence the entire forum devoted to them. I am about to tread into deep deep water, and here my inexperience is definitely going to become apparent. For my first look at optics on the GK1, my goal was simple. Let’s get something on there besides the iron sights.

The dovetail mount on the pistol only extends down the front ¾ of the pistol. This introduces several problems. For mounting a Red Dot sight, it feels a little too forward. I don’t know if there are functional problems with mounting a Red Dot sight slightly forward, but it does make focusing on the red dot a little more difficult and makes the field of view within the confines of the rim of the optic smaller.

Also, it is a dovetail mount. Most optics are going to be based on a picatinny mount. Or Red Dot pistol specific (the most common footprints being RMR and Docter).

Once you add an optic with magnification, the forward mounting rail really becomes a problem. Magnified optics have a very specific eye-relief distance--that is the distance that your eye must sit behind the lens. If your eye is not at that distance, then you see nothing thru the scope. Having the scope too far forward leads to very awkward shooting positions, with you essentially kissing the pistol grip.

To get start on mounting optics, I threw on this dovetail offset adapter I had laying around, to try and move the optics backwards.

And the first thing I threw on there was this pic rail mount cheap Walther red dot. It’s pretty fun and plenty accurate. As mentioned above, I did run into the Height-over-bore issue with close range shooting. Now that I look at the picture, it’s pretty obvious as the scope is sitting quite high due to the adapter.

If I were to keep the red dot scope, I would develop (or just purchase from Huben3dparts) a rear mount low profile adapter.

But I decided against keeping the red dot for a few specific reasons: I am lazy and have older vision. I found that when I have to zero a red dot scope, at any useful range, I could not make out the impacts on my target. I would have to walk over to the target to check it out, maybe even take a picture of my target, as the target paper filled up with holes, At one point, I tried to hack the situation by positioning a spare Ring camera I had around pointed at the target, but then I was constantly having to check my phone to find the POI.

So I quickly changed out to a ranged scope (Bugbuster side parallax), I could fire-adjust-fire, no need to walk over--as long as I put it somewhere on the box.

I like the idea of a red dot--super quick to put on target. But also perhaps since I’ve used scopes from the start, and scopes with close focus parallax adjustment (UTG Bugbuster and Hawke Airmax Touch), I prefer to have magnification. I probably won’t even revisit this, as I don’t own any RMR mount optics, and don’t really have any plans to, and there is a great inexpensive product out there already.

I will however, develop a dovetail-to-picatinny rail that will extend all the way to the rear of the pistol (and beyond).

Thanks for the write-up!
I went through a similar thought process. As I already have a PP800R micro-carbine, I already knew what works for me.
I ended up with a Leupold RDS (Freedom) red dot. This is one of the few red dot sights with a finger turnable elevation turret, and the adjustment is 1/4 MOA. The dot size is 1 MOA.
My eye sight is good enough to put the dot on small targets. Like @Navig said, the issue is having to check the target to see the POI.
For that, I have a quadrant target for closer (50 yards) target shooting. For anything out to 100 yards, even my 14x scope is not enough to see the POI. I have to walk to the target anyway.
I may take some pictures today!

 

[RAMJET66]

Another little side note. If you are going to be tinkering on a GK1, highly recommend getting a hex key set, and not a fold-out set. I am constantly using smaller metric units, not only just on the GK1, but on mounting rails, optics, just about anything. It is so convenient to have a set of handled individual hex drivers. I picked up this set on sale for like $12 at my local Harbor Freight.

View attachment 441754

i got the same set yesterday , but not on sale , they were 19.99 plus tax

 

[Navig]

And the undisputed first thing to 3D print for your GK1:

Fill-port plug

Here was my design for a simple Fill-port plug.

Nothing fancy like O-ring slots. Nope. The important measurements are labeled (in mm). I chose a shaft radius of 2.3mm because I found this the perfect radius, where one wrap of electrical tape gives you a perfect fit (stays in snug, but easy to remove)

Additional details: the hex is max width 4mm and height of 4mm. The dome is an exact half dome.

Additional design note: Sketchup could not create the dome in its original size (using the Follow-Me tool) because it couldn’t work the math in such small dimensions. So I designed it in centimeters, and when I was done, scaled it down by /10.

This was sliced at 210C 1mm thick walls 10% gyroid infill on Inland PLA.

What can I say? It’s a fill port plug. But 3D printing production is under way!

 

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