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

[Navig]

Alternative title: A dude, a GK1, and a 3d printer.

Hi all!

I’ve been on a journey to create my own GK1 mini-carbine, DIY style, although with a 3D printer. So I figured I would reserve a little corner of the online GK1 world and post my experience, from the very beginning. This mission has been inspired and educated from the various GK1 threads on this forum. I am fairly novice to both pcp air guns and 3d printing, so I plan on keeping everything at a very accessible level.

Who am I? And why (and even what is) a mini carbine?

My whole air gun history is contained in this thread here.

Basically I have an almond farm, and just part of what must be done is squirrel control. I started with the classic Benjamin Marauder full length rifle, then moved on to semi-auto (squirrel hunting lends itself to quick follow up shots). But over time, just the nature of a tree farm (limits visibility distance) and squirrels (constantly moving) dictated something smaller and lighter. While I was moving in that direction (AEA HP SS+), it wasn’t really until I came across the GK1 micro carbine thread, that I learned what I wanted had a name.

Micro carbine--is it compact lightweight rifle or is it a pistol with a stock? Who cares, what I wanted/needed had a name: the GK1.



So: I put and order in at Ares Air guns, and early January, it arrived:

Additional items in the order: Ares end cap thread adapter and Huggett Snipe moderator (more on these items later.)






First order of business, document everything is there.

And all the little parts:

 

[ChRiSiS]

Alternative title: A dude, a GK1, and a 3d printer.

Hi all!

I’ve been on a journey to create my own GK1 mini-carbine, DIY style, although with a 3D printer. So I figured I would reserve a little corner of the online GK1 world and post my experience, from the very beginning. This mission has been inspired and educated from the various GK1 threads on this forum. I am fairly novice to both pcp air guns and 3d printing, so I plan on keeping everything at a very accessible level.

Who am I? And why (and even what is) a mini carbine?

My whole air gun history is contained in this thread here.

Basically I have an almond farm, and just part of what must be done is squirrel control. I started with the classic Benjamin Marauder full length rifle, then moved on to semi-auto (squirrel hunting lends itself to quick follow up shots). But over time, just the nature of a tree farm (limits visibility distance) and squirrels (constantly moving) dictated something smaller and lighter. While I was moving in that direction (AEA HP SS+), it wasn’t really until I came across the GK1 micro carbine thread, that I learned what I wanted had a name.

Micro carbine--is it compact lightweight rifle or is it a pistol with a stock? Who cares, what I wanted/needed had a name: the GK1.



So: I put and order in at Ares Air guns, and early January, it arrived:

View attachment 437394

Additional items in the order: Ares end cap thread adapter and Huggett Snipe moderator (more on these items later.)






First order of business, document everything is there.

View attachment 437395





And all the little parts:

View attachment 437396

Looking forward to seeing the rest of the story/journey. Please don’t make me wait too long, I’ve got a GK1 that’s hankering to grow up into a micro carbine!

Chris

 

[Navig]

My apologies! While I will try and generate content as fast as possible, I am essentially using this thread as a brain dump for pretty much everything I have learned from the moment I opened the box. And geared toward folks for whom this might actually be their first pcp. If you want, there are many examples, both commercial and DIY (including the 90% completed version of mine) on this this thread.

 

[Navig]

Next order of business: Let’s make sure it works out of the box.


** Edit--the general experience is whenever possible, load pellets before adding pressure (so skip down to the loading pellets section). Doing so allows you to operate the magazine release lever under significantly less tension.

I pressurize with an Air Venturi Rovair, my backup is a Air Venturi refurb carbon fiber tank (my local scuba shop refills me at $100 for 10 fills), and a Hill Mk4 hand pump. For how-to’s regarding filling, see the How-To section of the forums.

Using a high pressure airgun compressor is fairly easy. Set the pressure on the dial. Connect the included fill probe to the quick release foster fitting on the end of the compressor hose. Insert the fill probe/hose into the GK1. Turn the compressor power on. Select 120VAC. Push the green Go button. Close the bleed valve knob. Filling to 4500psi/310 bar takes about 7 minutes. The compressor shuts off automatically. Open the bleed valve and release the hose pressure. Remove the fill-probe. Good to go.

 

[ChRiSiS]

My apologies! While I will try and generate content as fast as possible, I am essentially using this thread as a brain dump for pretty much everything I have learned from the moment I opened the box. And geared toward folks for whom this might actually be their first pcp. If you want, there are many examples, both commercial and DIY (including the 90% completed version of mine) on this this thr

No apologies necessary. I wasn't criticizing or trying to hurry you up. Rather I was simply expressing my interest in a hopefully humorous way.

 

[Navig]

I'm so excited to share my experience, and still loving it--but it takes a heckofalotta time to post. I just spent 2 days ruminating and editing my thoughts just on loading pellets! And here we go...

 

[Navig]

Pistol is pressurized, time to load pellets!


Loading Pellets

The first step to loading pellets is to release the magazine release lever--Depending on your version, it may be up, it may be down. I have V2, to release, lift it up:

And here comes the first GK1 commandment:

Baby the magazine release lever. Do not let it hard snap!

There are plenty of reports of this lever snapping due to mishandling. In fact, I went ahead and purchased a replacement, in case I got ham handed!

 

[Navig]

Next step: Load the pellets

Loading the pellets with the stock load gate:

I think the best way to load pellets is to use 2 hands. Right hand to manage the pellet, left hand to rotate the magazine. In order to free up 2 hands, I either secure the pistol in my tripod, or I prop the tip of the pistol on something soft but firm and rest the stock on my chest--that way I have 2 hands. Using my right hand, I reach into the tin of pellets, load one pellet, push it into the magazine. In the macro zoom picture, you can see that when you press a pellet in to the magazine, it bends the flappy flange. When the pellet seats, the flange snaps back into straight with an audible “ping”. When I reach for the next pellet, I use my left hand to rotate the magazine, so that the next open spot is in the load position.

There are 2 spots to load a pellet, the one at 90 degrees, and the one just above. You would think that the one below might support receiving a pellet, but a close examination of the flange shows that it is too stiff to load in this position.

You could also load 2 pellets with your right hand, then advance the magazine twice, and repeat.

Prior to receiving the GK1, I had thought that a custom loading gate (ie “speed loader”) was going to be one of the first things I would want. A custom loading gate, such as depicted at the Huben store, flips fully open, getting rid of the loading flange; that allows you to load 3 pellets at a time.

After having loaded several thousand pellets at this point, my conclusion is that the rate limiting step is NOT how many pellets you can load at once--by far the limiting step is rummaging around in the tin to pick up the next pellet, and put it in the proper orientation for loading. I found no difference in loading 1 pellet or 2 pellets at a time, so I doubt there would be a difference going from 2 to 3. I went in to purchasing this pistol thinking one of the first mods I would “need” would be a “speed loader”, but now that I’ve spent time with it, it has become a much lower priority. Additionally, I actually like the function of the flexible flap/flange--it gives you positive feedback that the pellet is properly seated when it “pings”.

Here is a video of me loading 1 at a time followed by 2 at a time.

Pardon my clumsiness--it was hard to manage positioning for lights, camera tripod with big zoom lens, etc.


If you are loading the pistol by picking it up and putting it down between each repetition of loading pellets, or with only 1 hand, then I imagine a speed loader will help significantly. I think that propping it up and using 2 hands is still much faster.

 

[Navig]

Ammunition:

There are massive threads devoted to ammunition for this pistol. For now I am sticking to the standard pellet shape, aka diabolo. It appears that this pistol is specifically designed for diabolos, as there is a slight chamfer in the magazine chamber that seats a diabolo shape and lessens the chance of it accidentally falling forward or backwards. See Steve-I's post.

I am using JSB Jumbo Heavies, 18.13gr.

The final thing about loading pellets specific to the GK1. In the.22: When your pellet is the last one visible on the left, advance the magazine twice and it will be in the firing position. Obviously, it is moot if you have filled all the chambers.

And the final final thing about loading pellets. Now that the pellets are loaded, carefully release the magazine lock lever back into place.

 

[longdog]

I always load before I pressure up the gun…..noticeably less stress on the lever/components.

 

[Nomadic Pirate 66]

I always load before I pressure up the gun…..noticeably less stress on the lever/components.

This was one of the best tips I got back even before getting the pistol.

 

[Nomadic Pirate 66]

Next step: Load the pellets

Loading the pellets with the stock load gate:

I think the best way to load pellets is to use 2 hands. Right hand to manage the pellet, left hand to rotate the magazine. In order to free up 2 hands, I either secure the pistol in my tripod, or I prop the tip of the pistol on something soft but firm and rest the stock on my chest--that way I have 2 hands. Using my right hand, I reach into the tin of pellets, load one pellet, push it into the magazine. In the macro zoom picture, you can see that when you press a pellet in to the magazine, it bends the flappy flange. When the pellet seats, the flange snaps back into straight with an audible “ping”. When I reach for the next pellet, I use my left hand to rotate the magazine, so that the next open spot is in the load position.

View attachment 439870

There are 2 spots to load a pellet, the one at 90 degrees, and the one just above. You would think that the one below might support receiving a pellet, but a close examination of the flange shows that it is too stiff to load in this position.

You could also load 2 pellets with your right hand, then advance the magazine twice, and repeat.

Prior to receiving the GK1, I had thought that a custom loading gate (ie “speed loader”) was going to be one of the first things I would want. A custom loading gate, such as depicted at the Huben store, flips fully open, getting rid of the loading flange; that allows you to load 3 pellets at a time.

After having loaded several thousand pellets at this point, my conclusion is that the rate limiting step is NOT how many pellets you can load at once--by far the limiting step is rummaging around in the tin to pick up the next pellet, and put it in the proper orientation for loading. I found no difference in loading 1 pellet or 2 pellets at a time, so I doubt there would be a difference going from 2 to 3. I went in to purchasing this pistol thinking one of the first mods I would “need” would be a “speed loader”, but now that I’ve spent time with it, it has become a much lower priority. Additionally, I actually like the function of the flexible flap/flange--it gives you positive feedback that the pellet is properly seated when it “pings”.

Here is a video of me loading 1 at a time followed by 2 at a time.

Pardon my clumsiness--it was hard to manage positioning for lights, camera tripod with big zoom lens, etc.


If you are loading the pistol by picking it up and putting it down between each repetition of loading pellets, or with only 1 hand, then I imagine a speed loader will help significantly. I think that propping it up and using 2 hands is still much faster.

Absolutely agree with you,

As I pick up the next pellet in the tin my left hand is rotating the magazine, I cannot pick up the pellets any faster so I have no need to be able to load 2 or 3 at a time

 

[sactargetshooter]

Alternative title: A dude, a GK1, and a 3d printer.

Hi all!

I’ve been on a journey to create my own GK1 mini-carbine, DIY style, although with a 3D printer. So I figured I would reserve a little corner of the online GK1 world and post my experience, from the very beginning. This mission has been inspired and educated from the various GK1 threads on this forum. I am fairly novice to both pcp air guns and 3d printing, so I plan on keeping everything at a very accessible level.

Who am I? And why (and even what is) a mini carbine?

My whole air gun history is contained in this thread here.

Basically I have an almond farm, and just part of what must be done is squirrel control. I started with the classic Benjamin Marauder full length rifle, then moved on to semi-auto (squirrel hunting lends itself to quick follow up shots). But over time, just the nature of a tree farm (limits visibility distance) and squirrels (constantly moving) dictated something smaller and lighter. While I was moving in that direction (AEA HP SS+), it wasn’t really until I came across the GK1 micro carbine thread, that I learned what I wanted had a name.

Micro carbine--is it compact lightweight rifle or is it a pistol with a stock? Who cares, what I wanted/needed had a name: the GK1.



So: I put and order in at Ares Air guns, and early January, it arrived:

View attachment 437394

Additional items in the order: Ares end cap thread adapter and Huggett Snipe moderator (more on these items later.)






First order of business, document everything is there.

View attachment 437395





And all the little parts:

View attachment 437396

Way cool! I have an Artemis PP800R in .177 (think of it as a regulated Diana Bandit, not exactly in the same league as a GK1), added a folding shoulder stock, a picatinny rail, and it is a very light and pointable airgun. And yes, I would use the term micro-carbine to describe it.

Just a few things to watch out for. The scope/optic height relative to the shoulder stock cheek position is an important consideration. In my case, I want a point-blank-range (PBR) of 8 to 15 yards (at 6 FPE, this PBR is quite appropriate!), the optic (red dot) has to be mounted low. This means the shoulder stock also need a cheek position that matches the optic height. If the PBR is not important, then obviously one can use a riser to adjust the height of the optic.

Unlike a bullpup or the Leshiy, the GK1 has a *very* low dovetail rail. Combined with a higher muzzle velocity, a GK1 can have an extended PBR with a red dot. I think this is one of the best part of the geometry of the GK1.

 

[Navig]

I always load before I pressure up the gun…..noticeably less stress on the lever/components.

That sounds like a solid recommendation. My understanding is that the release lever is under system pressure, but I don't know the mechanims well enough to say. I will pay attention the next time I'm loading.

I do plan on experimenting with speed loaders, will circle back to it some time.

 

[elwoodblues]

I have always filled the mag before the air on the GK1, on the K1 not as big a deal as its regulated and is set at about the point of refill

 

[Navig]

Sactaregetshooter--Sounds like you are referring to what I researched as "Height over bore". I ran in to this phenomenon because it rained nearly constantly in NorCal in January and February. So I had to do a lot initial shooting in my shop, which gives me a range of about 30 feet. When I moved outside to a longer distance, my point-of-impact was above my crosshair, which might be counterintuitive--usually the longer away the target, you want to aim higher to account for pellet drop. Instead, I had to aim lower to hit the farther target. As you said, in close close range, the height of the optic above the bore of the barrel, comes in to play. So you have to account for it, or minimize it by mounting the optics as low as possible. More on that when I get to mounting optics and designing my optics rail.

In summary you have 3 ranges. In ultra short range, the height of you optic causes the point of impact to be lower than you might expect. Normal range is where you typically will have your optics adjusted. Then ultra far range, your point of impact will once again fall below your crosshair as the pellet start dropping. The difference between ultra short and normal range can be minimized by keeping the optic as close to the level of the barrel as possible.

 

[Navig]

Paying attention to it today, filled at 4500 psi (310 bar) vs 2 magazines later (180 bar). at the lower pressure, there is noticeably less force necessary to operate the lever.

So: whenever you can, load pellets before pressurizing.

 

[longdog]

man, there are a lot of smart people on this forum…..

 

[RIshooter]

Sactaregetshooter--Sounds like you are referring to what I researched as "Height over bore". I ran in to this phenomenon because it rained nearly constantly in NorCal in January and February. So I had to do a lot initial shooting in my shop, which gives me a range of about 30 feet. When I moved outside to a longer distance, my point-of-impact was above my crosshair, which might be counterintuitive--usually the longer away the target, you want to aim higher to account for pellet drop. Instead, I had to aim lower to hit the farther target. As you said, in close close range, the height of the optic above the bore of the barrel, comes in to play. So you have to account for it, or minimize it by mounting the optics as low as possible. More on that when I get to mounting optics and designing my optics rail.

In summary you have 3 ranges. In ultra short range, the height of you optic causes the point of impact to be lower than you might expect. Normal range is where you typically will have your optics adjusted. Then ultra far range, your point of impact will once again fall below your crosshair as the pellet start dropping. The difference between ultra short and normal range can be minimized by keeping the optic as close to the level of the barrel as possible.

I use a canted red dot on my rifle. It works great for 30yds and under. Eliminates the problem you've described.
On my pistols, I also use a red dot and have not really noticed much difference in poi between 5-20 yds.
Do you think this is attributed to the height over bore being low, or just the nature of red dots vs scopes?

 

[Navig]

Not sure, getting beyond my basic experience. I will post about my experiences in red dots and scopes later.

Side note--make a firing range
If you are starting out with air rifles, the first thing you need is a safe range and a target. My range is my front driveway into one of my wood piles, 50 feet as pictured. If it is raining, which it was for most of January and February, I can shoot inside my shop, which gives me a distance of about 30 feet. Obviously, make sure everything is safe for a long ways downrange.

By backing up, I can extend this to about 100 feet, but I rarely ever am shooting that far.



My target is an Amazon Prime box, duct tape top (makes it water resistant), and filled with rubber mulch. Then I tape or staple a piece of target paper--when I got my first Synrod, Pyramyd Air threw in a stack of these targets, and I haven’t had a need to buy any more as of yet. Whole thing rolls around on moving dolly.

Next thing is a stable firing platform. That way you can get a better idea to answer the question--is the gun and optics accurate, or is it me? I use a Bog Deathgrip tripod, which is comfortable and convenient for me. Undoubtedly not as accurate as a firing rig on a table, but for me is good enough to dial in accuracy for squirrels.

And finally, before shooting, if you really want to start analyzing performance, you need a chronograph. I am using the FX pocket chronograph V2. Attached for now with packaging tape!